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ashmccormick
17th September 2015, 10:35 AM
Gday guys,

Thought I would do a write up of a full cooling system overhaul I did recently, I took my time and took pics along the way. Only working part time atm so have way too much free time on my hands haha! :1087:

Its not a hard job at all but I was looking for a write up like this a few years ago when I had a first crack at it, and had to learn a few things the hard way so have been meaning to do this writeup for anyone else who is in the position I was.

So without further rambling here it is:


Parts/Tools needed:
- 13ltrs good quality coolant premix (concentrate and distilled water)
- Thermostat 76 degrees, preferably Nissan Genuine
- Gasket set for both thermostat and thermostat housings and long bolt for housing (genuine kit for sale on Patrolapart.com)
- Upper and Lower Radiator hoses
- New Radiator
- New Radiator cap (Genuine if possible)
- New Hose Clamps for all hoses
- New Heater hoses (IF NEEDED)
- New water pump and gasket (IF NEEDED)
- New Drive Belts (IF NEEDED)
- Socket set
- Tap and Die set
- Screwdrivers of various lengths, Phillips and flathead
- Sandpaper
- Loctite and gasket sealer
- Anti seize or grease

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1. drain cooling system:

NOTE: I didn’t use any coolant flush products as my system was flushed thoroughly last year. If you just bought the car/not done a flush for years etc then it might be worthwhile to do this! Just follow what the bottle says.

Remove radiator cap, and loosen radiator bleed screw (located bottom left of radiator TD42 and right for TB42) and place tub under tube to catch fluid.
If the screw is too tight/cant find it etc. just loosen bottom radiator hose clamp and pull hose off the radiator. This is messy but much quicker than waiting for the radiator bleed.
WARNING: Coolant is potentially deadly for pets and small kids, so dispose of it carefully, wash up any spillages thoroughly!

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2. While its draining take the time to check over the engine fan and coupling (this should be firm to spin by hand, and should have no play in it when you try and rock it side to side, check it for any oil leakage) and get a torch to look at condition of air con condenser in front of the radiator, its most likely full of mud, insects, grass and other gnarly looking stuff that will need to be cleared later. No point spending hours working on a cooling system that’s not going to get airflow through it due to a clogged up condenser!
As you can see in the pics mine was full of spear grass seeds and mud so I took the grille off to access it whilst still waiting for the coolant to drain. You can also see where my thermostat housing was weeping coolant in the other picture.

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3. Once the radiator has fully drained its time to drain the coolant from the engine block: Get under the car and look up the passenger side of the engine block behind exhaust manifold there’s a 12mm sump plug located up there (arrow in pic below). Note: the location of this will most likely vary between the 2.8, 3.0 and TB42 engines so check out a manual for the location on your engine.

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This plug is a bit of a PITA to get access to, and when you do get it out coolant will absolutely blast out of there so get a big tub to try and catch it, but its most likely gonna go everywhere. The pro tip here is to position yourself as far away from the engine towards the front of the car as possible and don’t get covered in the stuff!

4. Now you have drained the coolant its time to flush out any remaining old coolant/debris build up in the system.
Leave the sump out and don’t lose it! tighten up the radiator drain plug or slide the hose back onto the radiator, if you took that off, and run water from a hose pipe through the top of the radiator. Keep it flowing until you can see clear water coming out of the block.

5. Take off the bottom radiator hose again and repeat the process until clear water is coming out of the bottom of the radiator this time, as some will still be in here despite the block water looking clean.

6. While waiting for water to stop dripping out of the cooling system take the coolant reservoir out and give that a thorough rinse and wipe clean with a cloth. Also clean out the hoses incase they are blocked up. My reservoir and hoses were filled with mud when I bought my car. If you don’t clear out blockages in the reservoir hoses then your system wont work properly.

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7. Once water has stopped dripping out of the engine block put that block plug back in with a little Loctite and torque it up to about 25Nm. You can do this anytime, I just prefer to do it straight away so I don’t forget or lose the damn thing! Give it a clean up and make sure its not too corroded first!

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8. Take off the radiator hoses and put them in the back of the car to save for spares. If they’re stuck on tightly then carefully slide a flat head screwdriver under the lip while jogging the hose around to help get them off. Just try not to scratch up the thermostat housings or radiator outlets too much.
Also take off the smaller hoses and give them a rinse to make sure they’re not clogged up either.

9. Unbolt the plastic shroud/guard from the radiator. Move the shroud away from the radiator to give it enough room to get out (or take off the smaller section and remove it from the engine bay if your clips haven’t been damaged from last owner!)

10. Remove the 2 top radiator bolts, double check that no hoses are still attached to the radiator, and then carefully pull the radiator up and out of the engine. Radiators are prone to damage so go slow and steady, you don’t want it to go banging off things or dropping it.
Give it a thorough check for any damaged fins and clear out any blockages with compressed air or gently with water. Again go steady if youre using pressure washer as it may damage fins. Leave the radiator to one side for now.
If the radiator is old and you have had overheating problems recently you might want to consider taking it into a radiator specialist to re-core or just buy a new heavier duty replacement as I did.

I bought a new radiator so thankfully I didn’t have to worry too much about cleaning up this mess!! Carving out tracks to the best fishing spots comes at a price!

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11. While you have the air compressor or other weapon of choice out, get busy on the aircon condenser if that’s blocked too. Like I said earlier, you need the airflow through both to get good cooling efficiency so be thorough.
Also at this stage, if you have an electric thermo fan fitted to the aircon condenser check that over and check wiring is intact etc.

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12. Now that the radiator is out of the way there’s heaps more room to get busy with a socket set for the rest of the jobs; Loosen all drive belts that are attached to the water pump and fan and remove (Replace belts if they look damaged or are old etc).

13. Remove the engine fan and coupling from the water pump and put aside. Unbolt the water pump and remove to inspect its condition; it should spin freely, if there’s any noise or heavy corrosion it’s no good. To be honest you might as well just change it now unless you know it’s new. Now clean up the water pump surfaces with a bit of sandpaper, line up the gasket with a thin layer of sealant to hold it steady and bolt back in to torque specs.

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Leave the fan off for now and leave belts off too.
14. Unbolt the 3 bolts holding in the top of the thermostat housing. And remove from the bottom housing.

WARNING! This bolt here that the socket is on (pic below) is a long bolt that goes through both top and bottom housings and bolts into the block underneath. It’s a prick of a design as its high tensile steel sitting inside alloy that is expanding and contracting under heat and potentially water/coolant if theres been a leak, prone to seizing.
If its not been out for years, or you have coolant leaking from the top of the thermostat housing its most likely seized! Seen and heard it happening to lots of TD42’s. Be prepared to get creative with a hacksaw or similar and some kind of screw extractor if this happens.

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15. Remove the heater hoses from the lower thermostat housing, remove the water temp sensor and thermal transmitter wires (Don’t lose the metal pin off the temp sensor!). Undo the 5 remaining bolts and take off the housing.

16. Use sand paper to clean up all the mating surfaces of both upper and lower housings, and the engine block.
Remove the rectangular rubber gasket on the left carefully and clean up the surface around it.
Remove the old thermostat from the housing and clean up that surface too.

Be careful to not get any debris into the block/top of the water pump. Shove a cloth in there to catch debris.

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17. While the housing is off the engine it pays off to clean up all threads with a suitable Tap and Die tool. If you have one its worth cleaning up threads on block and the bolts also. As stated earlier they are prone to seizing so good quality threads make a world of difference for future jobs.

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18. Once all surfaces are clean fit new gaskets to block, it helps to use sealer on the right hand gasket to keep it in place, but DON’T use any on the left side rubber gasket.

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19. Refit lower thermostat housing to the engine and torque bolts up to about 20Nm. That’s not much force so go easy because use too much force and you’ll strip the treads and be in a world of pain and misery… Trust me haha!
Tips here: - Use a liberal amount of anti-seize on all bolts for future.
- Line up all bolts and make sure they are all in before tightening, because they absolutely will not line up if you go one at a time.
- Make sure the rubber washer stays in place before you tighten up the housing.
- It really helps to put long bolt in also at this stage so that you know it will line up later when you put the top housing back on.
- Don’t forget any cable holders/earths etc that were attached to any bolts.

20. Refit electrical components to housing, Refit heater hoses (fit new ones if old ones are knackered). Place the new thermostat into its slot and then apply gasket sealer and gasket over the top of it.

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21. Give the long bolt another smear of anti seize just for good luck then bolt in the upper thermostat housing. Again don’t go over tightening these bolts because they’ll strip and then you’ll be back in the world of pain!... Been there as well :/

The bolts literally just need to be nipped up a quarter turn or so from when you start to feel resistance (16-21Nm)

22. If you got this far without hitting any major snags and running out of swear words congrats!

Now it’s just a case of reversing what you took off
23. Refit Fan to water pump (replace if needed)
24. Refit Drive belts (replace if needed)
25. Put radiator shroud back in engine bay
26. Refit the radiator or if you have a new radiator then remove all rubber mounts from the old radiator and fit to your new one before installing.
NOTE: when putting the radiator in make sure the rubber mounts are securely in place at the bottom of the radiator before tightening up the top mounting bolts.

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27. Once the radiator is in, fit the new radiator hoses to the radiator ports then onto the thermostat housings ensuring hose clamps are reasonably tight.
TIPS: -Be careful not to damage the radiator ports when putting hoses on.
-If the hoses are difficult to slide on then try soaking them in warm water, or apply a coating of coolant all over the end of the hose. Some people also use soap or Vaseline.
-Don’t over tighten the hose clamps as this will probably cut into the hose and you’ll have a leak in no time at all. Just tighten it until there is a slight bulge in the hose either side of the clamp, and the hose cant be spun or moved around at all.
-Always slide hose clamps onto hose before installing it. Rookie mistake that one! Also position the tightening screw in a position that’s not gonna be a real PITA if you have to undo it on the tracks etc.

28. Refit plastic radiator shroud to radiator

28. Make sure aircon condenser is clear, thermo fan replaced etc.

29. Refit grille if removed (don’t leave any tools behind it)

30. Final check over: make sure all hoses are back on, no earth points left out from under bolts, drive belts are tight, fan is back on, water pump and thermostat housings all tight and fully bolted in, radiator hoses tight, block drain plug is in, radiator drain plug is tight, no tools/rags lying around moving parts...

31. Fill the coolant reservoir with coolant up to the min level line and tighten back up the cap.

32. Fill the cooling system up through the radiator filler neck. Should take a while and will probably bubble up as air is pushing back through the system. Keep filling until the level stays steady up at the top of the filler cap.

33. Time to bleed the system:
TIP: It helps to have the front of the car raised up so that your filling point of coolant is the highest point of the engine. Park on a hill, or jack up the car securely and use a coke bottle or similar like picture below, try and keep airtight, I just wrapped a bit of electrical tape around the cap.

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To bleed system:
-Turn the heater to hot inside the car, don’t really need blower on, but in the hot position.
-Get a supply bottle of coolant ready to keep topping up the system and watch the level inside the filler neck.
-Keep the radiator cap off and start the engine.
-As the system starts to flow the fluid level in the neck will drop due to air rising up through the system so wait for the fluid to drop and then keep adding more. Using the coke bottle method makes it easier to see the level and also the air bubbles escaping.
-Keep doing this until the top radiator hose is getting hot to touch, and no bubbles are coming up through the system anymore. It should take about 15 mins or so to reach operating temperature. And this can be speeded up by keeping the revs at about 2000rpm, use the throttle lock or get a mate to help you. Once all bubbles are finished and fluid level is staying constant place the radiator cap on and take the car for a quick trip around the block.
-Then come back, switch off the engine and check for any leaks. If you used good gaskets, correct torques, quality parts and bled the system thoroughly you should have no dramas. Just keep an eye on the levels in the radiator and reservoir over the following days and if necessary add more coolant or re bleed if you have any dramas.

If your cooling system is working properly the coolant reservoir should sit on minimum line when engine is cold (providing you filled it to this level) and move up near full once its warm. As the car cools down again it seeps back out of the reservoir.

Cheers for reading and good luck!:bigthumbup:

Winnie
17th September 2015, 10:42 AM
Awesome thread mate, very handy!
Always good to keep the old hoses and belts too in the car somewhere. I had to use my old bottom radiator hose on our last camping trip when I got a hole in the new one. Was bloody glad I had that spare!!!

AB
17th September 2015, 05:17 PM
Very detailed write up mate, well done!

After the overhaul what differences in temp range did you find?

garett
17th September 2015, 05:24 PM
just wanted to know where you temp gauge sits ? mine sits a needle width above cold .... only seen it move once when we were towing a trailer up the parmesten highway

mudski
17th September 2015, 05:44 PM
Wow. Top write up there ol'chap!

ashmccormick
17th September 2015, 06:45 PM
After the overhaul what differences in temp range did you find?

Thanks AB,

Not been able to take the car on a good highway drive yet to test under load at high speeds. I run an aftermarket in hose temp gauge for more accurate readings so I will update this once Ive had a good highway run. Its 40 degrees up here atm so will be testing the system to harsh conditions.

While driving around under lower speeds my hose gauge has only sat around 70+ degrees (Nissan gauge around 1/4) since the overhaul. This is also in 40 degrees.

ashmccormick
17th September 2015, 06:56 PM
just wanted to know where you temp gauge sits ? mine sits a needle width above cold .... only seen it move once when we were towing a trailer up the parmesten highway

Hi Garett!

Before the overhaul a few weekends ago my guage was around 3/4 on highway in high ambient temperatures. Too close to the H symbol for my liking!

Are you driving a GQ? The factory gauges are a little inaccurate to be honest, I have an in hose temp gauge fitted (can see this in my first pic). The aftermarket gauge always moves way before the factory one so I mostly watch that one.

Not sure if your gauge is accurate mate because it should sit around 1/4 - 1/2 I think. Just above cold sounds a little low...

garett
17th September 2015, 07:45 PM
yeah got a GQ in ford badges, i think the thermostat has been removed as it takes 15-20 mins to get to cold. might think about a aftermarket gauge. or might just test it with a potentiometer.

ashmccormick
17th September 2015, 08:42 PM
yeah got a GQ in ford badges, i think the thermostat has been removed as it takes 15-20 mins to get to cold. might think about a aftermarket gauge. or might just test it with a potentiometer.

Not a bad idea mate, overcooling is not good for the engine either... Although i know which one I'd rather have problems with haha

ashmccormick
25th October 2015, 06:58 PM
Been meaning to update this thread with a few figures seen after overhaul of cooling system. Just come back from several weeks camping around North Kimberley so been a little late to do this.


The temperatures up here are ridiculous atm, 40 degrees and humid etc. Car was fully loaded, few items on roof rack including spare wheel etc. Hard conditions for any cooling system.
In my rig I have an in hose temp gauge fitted post thermostat, and an engine watchdog (sensor bolted to side of engine block). So I will give readings for these plus Nissan factory gauge position.

At low speeds, town driving and 4WD high range dirt:
Hose: 70 ish degrees
Nissan: 1/4 - 1/3
Watchdog: 80-90 degrees

On highway, 90-100k's an hour, middle of the day with air-con on
Hose: 80-86 degrees
Nissan: 1/2 - just below 3/4
Watchdog: 95-100 degrees

In cooler conditions early morning etc the car runs cooler.

I'm keen to hear how other peoples figures line up next to this, I feel like its running a little hot? But it could just be in my head and the fact that ambient temperatures are through the roof. If I start to push my speeds more than 90-100k's in the heat the gauges creep up instantly so I just tinker along at lower speeds. Then every now and again other GQ's also loaded up to the max go screaming past me with apparently no dramas whatsoever so am I just going mad with too many things to watch over haha?

sooty_10
25th October 2015, 09:58 PM
Been meaning to update this thread with a few figures seen after overhaul of cooling system. Just come back from several weeks camping around North Kimberley so been a little late to do this.


The temperatures up here are ridiculous atm, 40 degrees and humid etc. Car was fully loaded, few items on roof rack including spare wheel etc. Hard conditions for any cooling system.
In my rig I have an in hose temp gauge fitted post thermostat, and an engine watchdog (sensor bolted to side of engine block). So I will give readings for these plus Nissan factory gauge position.

At low speeds, town driving and 4WD high range dirt:
Hose: 70 ish degrees
Nissan: 1/4 - 1/3
Watchdog: 80-90 degrees

On highway, 90-100k's an hour, middle of the day with air-con on
Hose: 80-86 degrees
Nissan: 1/2 - just below 3/4
Watchdog: 95-100 degrees

In cooler conditions early morning etc the car runs cooler.

I'm keen to hear how other peoples figures line up next to this, I feel like its running a little hot? But it could just be in my head and the fact that ambient temperatures are through the roof. If I start to push my speeds more than 90-100k's in the heat the gauges creep up instantly so I just tinker along at lower speeds. Then every now and again other GQ's also loaded up to the max go screaming past me with apparently no dramas whatsoever so am I just going mad with too many things to watch over haha?
Today cruising back from Mildura fairly warm ambient temp driving at 110-120km/h my temps got to 105 with probe in top thermostat housing. If i dropped speed to 100km/h temp would be around 100 degrees or just under. Normally around town sits around the 80 mark +- 10 degrees.

Sent from my SM-G925I using Tapatalk

ashmccormick
25th October 2015, 11:02 PM
Today cruising back from Mildura fairly warm ambient temp driving at 110-120km/h my temps got to 105 with probe in top thermostat housing. If i dropped speed to 100km/h temp would be around 100 degrees or just under. Normally around town sits around the 80 mark +- 10 degrees.

Sent from my SM-G925I using Tapatalk

Cheers Sooty! You running a TD42 in your GU? Where does your factory gauge sit when temp is at 100ish out of interest?

Hodge
26th October 2015, 06:46 AM
Might be doing this shortly my self as who knows when the last time coolant was changed on my 42.

Patasaurus
26th October 2015, 06:46 AM
Nice write up ashmccormick! Super helpful to blokes like me still learning. Top effort

sooty_10
26th October 2015, 06:51 AM
Cheers Sooty! You running a TD42 in your GU? Where does your factory gauge sit when temp is at 100ish out of interest?
Yeah factory TD42T mate, non intercooled. Factory guage s sitting up 2/3 ish when around 100, but sits up 3/4 when around 105. Sits there quite stable and doesn't climb excessively quick. That was with the AC running too.

Sent from my SM-G925I using Tapatalk

ashmccormick
26th October 2015, 08:36 AM
Nice write up ashmccormick! Super helpful to blokes like me still learning. Top effort

Cheers mate! Thats what I was hoping to achieve as some of the 'easier' stuff tends to be covered in no detail which is daunting when youre having a first crack at something.

ashmccormick
26th October 2015, 08:38 AM
Yeah factory TD42T mate, non intercooled. Factory guage s sitting up 2/3 ish when around 100, but sits up 3/4 when around 105. Sits there quite stable and doesn't climb excessively quick. That was with the AC running too.

Sent from my SM-G925I using Tapatalk

Thanks for the info matey. Good to know my temps seem to be around the same as yours. Just need the turbo now haha!

ToddD42
5th December 2016, 09:45 AM
Sorry to dig up an old thread but Wicked write up ashmccormick!
Just doing an overhaul on my TD42T at the moment and was wondering what the go with the engine coolant sump is when putting it back in?
Is it based on a torque setting? And if so what torque? Don't have the service manual so im not sure and when i went to take it out originally i could still see thread on the outer of the bolt; if that makes sense.
TIA

jff45
5th December 2016, 08:09 PM
Todd, are you referring to the engine coolant drain plug?
It will have thread showing because it's a tapered thread that you can't screw right in.
I use a short stubby rachet to tighten mine with one hand after putting some RTV silicone on the thread.

ToddD42
6th December 2016, 10:50 AM
Todd, are you referring to the engine coolant drain plug?
It will have thread showing because it's a tapered thread that you can't screw right in.
I use a short stubby rachet to tighten mine with one hand after putting some RTV silicone on the thread.

Hey jff45!
Yer i was referring to the engine coolant drain plug. Ahh ok, so basically just make sure its in tight enough to create a seal - doesn't need to be torque specific.
Thanks for your help mate, appreciate it.

Sandgroper
13th March 2017, 09:39 PM
Thanks a mill for the write up!!!!! .... awesome to have it detailed in understandable terms!!!

I ended up replacing cheap big alloy with a custom Stage 2 Performance one from Brown's Radiators in Perth ..... $1100 .... but could never get water temp from hose reading above 90-95 even thrashing guts out of TD42 running 15PSI in sand dunes.

Safari-MI
11th September 2018, 04:58 AM
Very helpful write up. Thanks!

GeeeWizz
30th March 2019, 03:24 PM
Gday guys,

Thought I would do a write up of a full cooling system overhaul I did recently, I took my time and took pics along the way. Only working part time atm so have way too much free time on my hands haha! :1087:

Its not a hard job at all but I was looking for a write up like this a few years ago when I had a first crack at it, and had to learn a few things the hard way so have been meaning to do this writeup for anyone else who is in the position I was.

So without further rambling here it is:


Parts/Tools needed:
- 13ltrs good quality coolant premix (concentrate and distilled water)
- Thermostat 76 degrees, preferably Nissan Genuine
- Gasket set for both thermostat and thermostat housings and long bolt for housing (genuine kit for sale on Patrolapart.com)
- Upper and Lower Radiator hoses
- New Radiator
- New Radiator cap (Genuine if possible)
- New Hose Clamps for all hoses
- New Heater hoses (IF NEEDED)
- New water pump and gasket (IF NEEDED)
- New Drive Belts (IF NEEDED)
- Socket set
- Tap and Die set
- Screwdrivers of various lengths, Phillips and flathead
- Sandpaper
- Loctite and gasket sealer
- Anti seize or grease

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1. drain cooling system:

NOTE: I didn’t use any coolant flush products as my system was flushed thoroughly last year. If you just bought the car/not done a flush for years etc then it might be worthwhile to do this! Just follow what the bottle says.

Remove radiator cap, and loosen radiator bleed screw (located bottom left of radiator TD42 and right for TB42) and place tub under tube to catch fluid.
If the screw is too tight/cant find it etc. just loosen bottom radiator hose clamp and pull hose off the radiator. This is messy but much quicker than waiting for the radiator bleed.
WARNING: Coolant is potentially deadly for pets and small kids, so dispose of it carefully, wash up any spillages thoroughly!

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2. While its draining take the time to check over the engine fan and coupling (this should be firm to spin by hand, and should have no play in it when you try and rock it side to side, check it for any oil leakage) and get a torch to look at condition of air con condenser in front of the radiator, its most likely full of mud, insects, grass and other gnarly looking stuff that will need to be cleared later. No point spending hours working on a cooling system that’s not going to get airflow through it due to a clogged up condenser!
As you can see in the pics mine was full of spear grass seeds and mud so I took the grille off to access it whilst still waiting for the coolant to drain. You can also see where my thermostat housing was weeping coolant in the other picture.

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3. Once the radiator has fully drained its time to drain the coolant from the engine block: Get under the car and look up the passenger side of the engine block behind exhaust manifold there’s a 12mm sump plug located up there (arrow in pic below). Note: the location of this will most likely vary between the 2.8, 3.0 and TB42 engines so check out a manual for the location on your engine.

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This plug is a bit of a PITA to get access to, and when you do get it out coolant will absolutely blast out of there so get a big tub to try and catch it, but its most likely gonna go everywhere. The pro tip here is to position yourself as far away from the engine towards the front of the car as possible and don’t get covered in the stuff!

4. Now you have drained the coolant its time to flush out any remaining old coolant/debris build up in the system.
Leave the sump out and don’t lose it! tighten up the radiator drain plug or slide the hose back onto the radiator, if you took that off, and run water from a hose pipe through the top of the radiator. Keep it flowing until you can see clear water coming out of the block.

5. Take off the bottom radiator hose again and repeat the process until clear water is coming out of the bottom of the radiator this time, as some will still be in here despite the block water looking clean.

6. While waiting for water to stop dripping out of the cooling system take the coolant reservoir out and give that a thorough rinse and wipe clean with a cloth. Also clean out the hoses incase they are blocked up. My reservoir and hoses were filled with mud when I bought my car. If you don’t clear out blockages in the reservoir hoses then your system wont work properly.

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7. Once water has stopped dripping out of the engine block put that block plug back in with a little Loctite and torque it up to about 25Nm. You can do this anytime, I just prefer to do it straight away so I don’t forget or lose the damn thing! Give it a clean up and make sure its not too corroded first!

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8. Take off the radiator hoses and put them in the back of the car to save for spares. If they’re stuck on tightly then carefully slide a flat head screwdriver under the lip while jogging the hose around to help get them off. Just try not to scratch up the thermostat housings or radiator outlets too much.
Also take off the smaller hoses and give them a rinse to make sure they’re not clogged up either.

9. Unbolt the plastic shroud/guard from the radiator. Move the shroud away from the radiator to give it enough room to get out (or take off the smaller section and remove it from the engine bay if your clips haven’t been damaged from last owner!)

10. Remove the 2 top radiator bolts, double check that no hoses are still attached to the radiator, and then carefully pull the radiator up and out of the engine. Radiators are prone to damage so go slow and steady, you don’t want it to go banging off things or dropping it.
Give it a thorough check for any damaged fins and clear out any blockages with compressed air or gently with water. Again go steady if youre using pressure washer as it may damage fins. Leave the radiator to one side for now.
If the radiator is old and you have had overheating problems recently you might want to consider taking it into a radiator specialist to re-core or just buy a new heavier duty replacement as I did.

I bought a new radiator so thankfully I didn’t have to worry too much about cleaning up this mess!! Carving out tracks to the best fishing spots comes at a price!

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11. While you have the air compressor or other weapon of choice out, get busy on the aircon condenser if that’s blocked too. Like I said earlier, you need the airflow through both to get good cooling efficiency so be thorough.
Also at this stage, if you have an electric thermo fan fitted to the aircon condenser check that over and check wiring is intact etc.

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12. Now that the radiator is out of the way there’s heaps more room to get busy with a socket set for the rest of the jobs; Loosen all drive belts that are attached to the water pump and fan and remove (Replace belts if they look damaged or are old etc).

13. Remove the engine fan and coupling from the water pump and put aside. Unbolt the water pump and remove to inspect its condition; it should spin freely, if there’s any noise or heavy corrosion it’s no good. To be honest you might as well just change it now unless you know it’s new. Now clean up the water pump surfaces with a bit of sandpaper, line up the gasket with a thin layer of sealant to hold it steady and bolt back in to torque specs.

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Leave the fan off for now and leave belts off too.
14. Unbolt the 3 bolts holding in the top of the thermostat housing. And remove from the bottom housing.

WARNING! This bolt here that the socket is on (pic below) is a long bolt that goes through both top and bottom housings and bolts into the block underneath. It’s a prick of a design as its high tensile steel sitting inside alloy that is expanding and contracting under heat and potentially water/coolant if theres been a leak, prone to seizing.
If its not been out for years, or you have coolant leaking from the top of the thermostat housing its most likely seized! Seen and heard it happening to lots of TD42’s. Be prepared to get creative with a hacksaw or similar and some kind of screw extractor if this happens.

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15. Remove the heater hoses from the lower thermostat housing, remove the water temp sensor and thermal transmitter wires (Don’t lose the metal pin off the temp sensor!). Undo the 5 remaining bolts and take off the housing.

16. Use sand paper to clean up all the mating surfaces of both upper and lower housings, and the engine block.
Remove the rectangular rubber gasket on the left carefully and clean up the surface around it.
Remove the old thermostat from the housing and clean up that surface too.

Be careful to not get any debris into the block/top of the water pump. Shove a cloth in there to catch debris.

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17. While the housing is off the engine it pays off to clean up all threads with a suitable Tap and Die tool. If you have one its worth cleaning up threads on block and the bolts also. As stated earlier they are prone to seizing so good quality threads make a world of difference for future jobs.

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18. Once all surfaces are clean fit new gaskets to block, it helps to use sealer on the right hand gasket to keep it in place, but DON’T use any on the left side rubber gasket.

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19. Refit lower thermostat housing to the engine and torque bolts up to about 20Nm. That’s not much force so go easy because use too much force and you’ll strip the treads and be in a world of pain and misery… Trust me haha!
Tips here: - Use a liberal amount of anti-seize on all bolts for future.
- Line up all bolts and make sure they are all in before tightening, because they absolutely will not line up if you go one at a time.
- Make sure the rubber washer stays in place before you tighten up the housing.
- It really helps to put long bolt in also at this stage so that you know it will line up later when you put the top housing back on.
- Don’t forget any cable holders/earths etc that were attached to any bolts.

20. Refit electrical components to housing, Refit heater hoses (fit new ones if old ones are knackered). Place the new thermostat into its slot and then apply gasket sealer and gasket over the top of it.

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21. Give the long bolt another smear of anti seize just for good luck then bolt in the upper thermostat housing. Again don’t go over tightening these bolts because they’ll strip and then you’ll be back in the world of pain!... Been there as well :/

The bolts literally just need to be nipped up a quarter turn or so from when you start to feel resistance (16-21Nm)

22. If you got this far without hitting any major snags and running out of swear words congrats!

Now it’s just a case of reversing what you took off
23. Refit Fan to water pump (replace if needed)
24. Refit Drive belts (replace if needed)
25. Put radiator shroud back in engine bay
26. Refit the radiator or if you have a new radiator then remove all rubber mounts from the old radiator and fit to your new one before installing.
NOTE: when putting the radiator in make sure the rubber mounts are securely in place at the bottom of the radiator before tightening up the top mounting bolts.

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27. Once the radiator is in, fit the new radiator hoses to the radiator ports then onto the thermostat housings ensuring hose clamps are reasonably tight.
TIPS: -Be careful not to damage the radiator ports when putting hoses on.
-If the hoses are difficult to slide on then try soaking them in warm water, or apply a coating of coolant all over the end of the hose. Some people also use soap or Vaseline.
-Don’t over tighten the hose clamps as this will probably cut into the hose and you’ll have a leak in no time at all. Just tighten it until there is a slight bulge in the hose either side of the clamp, and the hose cant be spun or moved around at all.
-Always slide hose clamps onto hose before installing it. Rookie mistake that one! Also position the tightening screw in a position that’s not gonna be a real PITA if you have to undo it on the tracks etc.

28. Refit plastic radiator shroud to radiator

28. Make sure aircon condenser is clear, thermo fan replaced etc.

29. Refit grille if removed (don’t leave any tools behind it)

30. Final check over: make sure all hoses are back on, no earth points left out from under bolts, drive belts are tight, fan is back on, water pump and thermostat housings all tight and fully bolted in, radiator hoses tight, block drain plug is in, radiator drain plug is tight, no tools/rags lying around moving parts...

31. Fill the coolant reservoir with coolant up to the min level line and tighten back up the cap.

32. Fill the cooling system up through the radiator filler neck. Should take a while and will probably bubble up as air is pushing back through the system. Keep filling until the level stays steady up at the top of the filler cap.

33. Time to bleed the system:
TIP: It helps to have the front of the car raised up so that your filling point of coolant is the highest point of the engine. Park on a hill, or jack up the car securely and use a coke bottle or similar like picture below, try and keep airtight, I just wrapped a bit of electrical tape around the cap.

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To bleed system:
-Turn the heater to hot inside the car, don’t really need blower on, but in the hot position.
-Get a supply bottle of coolant ready to keep topping up the system and watch the level inside the filler neck.
-Keep the radiator cap off and start the engine.
-As the system starts to flow the fluid level in the neck will drop due to air rising up through the system so wait for the fluid to drop and then keep adding more. Using the coke bottle method makes it easier to see the level and also the air bubbles escaping.
-Keep doing this until the top radiator hose is getting hot to touch, and no bubbles are coming up through the system anymore. It should take about 15 mins or so to reach operating temperature. And this can be speeded up by keeping the revs at about 2000rpm, use the throttle lock or get a mate to help you. Once all bubbles are finished and fluid level is staying constant place the radiator cap on and take the car for a quick trip around the block.
-Then come back, switch off the engine and check for any leaks. If you used good gaskets, correct torques, quality parts and bled the system thoroughly you should have no dramas. Just keep an eye on the levels in the radiator and reservoir over the following days and if necessary add more coolant or re bleed if you have any dramas.

If your cooling system is working properly the coolant reservoir should sit on minimum line when engine is cold (providing you filled it to this level) and move up near full once its warm. As the car cools down again it seeps back out of the reservoir.

Cheers for reading and good luck!:bigthumbup:

:smiley_thumbs_up:

Appreciated the time taken to share experience with the less informed and the warnings on tasks that could become a new problem.
And the pictorial references really made things as simple as could be, now to put it all into perspective and get my hands dirty. :fish::xxxx:

BrazilianY60
7th August 2023, 10:44 PM
Thank you ashmccormick for the detailed explanation, much appreciated.

I am just flushing my TD42 cooling system and I don't currently have a heater core in place, as my GQ interior is fully stripped out at the moment. I have "looped" the thermostat housing in/out ports towards the heater with a piece of hose. I am wondering if this will prevent the thermostat from working properly, any comments on that?

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I think this would have the same effect as having the heater circulating water as in the procedure, but I'd rather be safe than sorry.

jff45
8th August 2023, 06:34 AM
I had to do that on the side of the road when my 18 year old heater core started leaking in the cabin after some bad corrugated roads. I left it bridged for over a year until I found the enthusiasm to take the dash out.
I didn't notice any ill effects or any change in operating temps.

BrazilianY60
8th August 2023, 11:05 AM
I had to do that on the side of the road when my 18 year old heater core started leaking in the cabin after some bad corrugated roads. I left it bridged for over a year until I found the enthusiasm to take the dash out.
I didn't notice any ill effects or any change in operating temps.

Thank you John!

BrazilianY60
21st August 2023, 01:08 PM
Gentlemen: The utterly badly located block drain plug is giving me a hard time. Every comment I see about undoing it seems to be for a GU, where you remove a rubber plate from the passenger's wheel well and you have straight line of sight to the plug, and from there you go with the 12 mm socket plus extension plus breaker bar. On the GQ, or at least in mine, there is no such rubber covered opening, it is sheet metal, so I cannot have a straight line of sight. I have tried to include a wobbly connector on that combination, but didn't have the proper way of applying "gentle force" with it.

Any suggestions on how to remove this without using a hole saw on the wheel well for proper line of sight?

Would a garden hose on the engine port that receives water back from the heater core, with the engine off, would be enough for water to come out on the other engine port towards the heater core and such be able to circulate the old water out? Not sure if the cold termostat of the non-running engine would block that water circuit?

Also, any other way I could do a flush and get rid of the in-block water? I've been thinking about using compressed air but not sure if that would break any seal.

PeeBee
21st August 2023, 09:04 PM
Gentlemen: The utterly badly located block drain plug is giving me a hard time. Every comment I see about undoing it seems to be for a GU, where you remove a rubber plate from the passenger's wheel well and you have straight line of sight to the plug, and from there you go with the 12 mm socket plus extension plus breaker bar. On the GQ, or at least in mine, there is no such rubber covered opening, it is sheet metal, so I cannot have a straight line of sight. I have tried to include a wobbly connector on that combination, but didn't have the proper way of applying "gentle force" with it.

Any suggestions on how to remove this without using a hole saw on the wheel well for proper line of sight?

Would a garden hose on the engine port that receives water back from the heater core, with the engine off, would be enough for water to come out on the other engine port towards the heater core and such be able to circulate the old water out? Not sure if the cold termostat of the non-running engine would block that water circuit?

Also, any other way I could do a flush and get rid of the in-block water? I've been thinking about using compressed air but not sure if that would break any seal.

You wont blow any seals as the system cant pressurize having the exit hole. The air will expand and push the water out. You could probably do a combination of the water hose and the air, but if the lowest drain point is still sealed up you wont do as good a job i suspect. Time to get out that hole saw or angle grinder!

BrazilianY60
12th September 2023, 03:52 AM
Time to get out that hole saw or angle grinder!

Had to do that at the end.