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!
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!
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Originally Posted by AB
