Help needed, TD42 running hot on highway..

Hi guys,

**Please note this is not a problem with the car 'overheating' past OEM specs, its the car running just below the first H line at highway speeds under load and I have just changed drive belts, new 3 core radiator, full flush/fresh coolant, new radiator cap, 1 yr old water pump, new viscous fan, new hoses, new thermostat (76*), New oils/filters, Burped the system of air, just adjusted the tappets...**

It's mid to high 40's out here in the Kimberley atm and my car has been running very hot on the highway over the weekend I never drove above 90 kph frequently backing off to 80 ish whenever the needle started to creep towards the first H line.

The engine feels as though it may be over fuelled as it smokes a little under load and can hear the fuel flow more when you put your foot down even though it has no effect on the revs.

The car has always seemed to run a little hot on the highway and now the ambient temps are through the roof its just getting worse. Once off the highway around town etc it runs very cool (around 1/4 - 1/3 factory gauge). So my main question is could an over fuelled IP be causing the engine to run hot under load? I have changed every aspect of the cooling system trying to cool it down! Or is it simply just normal TD42 life in very high ambient temperatures?

I am driving from Kimberley down WA and across the Nullabor in a few weeks and don't want to be sitting at 80 kph watching my temp gauge the whole time if it can be helped.

Cheers

Why not get a real temp gauge so you know what your engine is really doing.
A good temp gauge will even indicate how well your thermostat is reacting.

You could also add an EGT gauge if you want to keep an eye on your fuelling.

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Originally Posted by jff45

Why not get a real temp gauge so you know what your engine is really doing.
A good temp gauge will even indicate how well your thermostat is reacting.

You could also add an EGT gauge if you want to keep an eye on your fuelling.

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Hi John,

I have an in hose temp guage and an engine watchdog bolted to engine. In hose gauge needs a new thermal transmitter I think because it sits around 60-70. However they all creep up at the same rate as the factory gauge moves so I'm pretty sure the factory reading is on point.

I thought EGT readings were something turbo'd engines used, might be worth looking into!

I missed the N/A

What condition is your air filter in?

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Originally Posted by AB

What condition is your air filter in?

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Brand new, just serviced the car so new filters, oil, fuel filter etc.

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Originally Posted by jff45

I missed the N/A

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All good, I would like to turbo it in the near future anyway!

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Originally Posted by AB

What condition is your air filter in?

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x2 have you got a snockel it will allow more cooler air to go in the air box instead of heat of the road

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Originally Posted by roofy

x2 have you got a snockel it will allow more cooler air to go in the air box instead of heat of the road

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Yeh Roofy got a snorkel on it hoping it would ease the temps a little...

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Originally Posted by ashmccormick

Yeh Roofy got a snorkel on it hoping it would ease the temps a little...

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the other thing could be to heavy engine oil ask the locals what there running

Never even thought of that! I'm using 15w40 Diesel oil though, thats reasonably light isn't it?

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Originally Posted by ashmccormick

Never even thought of that! I'm using 15w40 Diesel oil though, thats reasonably light isn't it?

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that's what I'm using,gear box transfer case diffs maybe sluggish in need of a change
ambient temps might 40+ but roads are twice that there for diffs ect will heat up if oil
is past it

Has it always been like that and that's why you have done all that work or has it recently happened after the mentioned things above?

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Originally Posted by roofy

that's what I'm using,gear box transfer case diffs maybe sluggish in need of a change
ambient temps might 40+ but roads are twice that there for diffs ect will heat up if oil
is past it

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Yeh good point mate! Have to see what others are using out here. I run 80w90 for front diff, gearbox and transfer. And LSD oil in rear

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Originally Posted by AB

Has it always been like that and that's why you have done all that work or has it recently happened after the mentioned things above?

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Its always run pretty hot mate, thats why I have turned the cooling system upside down trying to see whats going on... Got a 3 core radiator as I thought that might help too.
Always blown quite a lot of black smoke. Perhaps new injectors could be worth looking at...

Do you have all the rubber curtains, foam strips etc in place?

You could also try blocking the bypass port in the thermostat housing.

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Originally Posted by nissannewby

Do you have all the rubber curtains, foam strips etc in place?

You could also try blocking the bypass port in the thermostat housing.

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Is the bypass port the hose that joins onto the radiator filler neck from the thermostat housing? Is there a downside to blocking this off? I'm assuming I have everything in place, no leaks or coolant loss.

If it's blowing heaps of black smoke could it be to rich??
Being an NA we don't have much room at all to move on fuel pump adjustment..
They will blow a little when under load but if your seeing black smoke when cruzing then it's possible to rich and thus causing extra heat in the engine..

Apart from that.
If you trust your secondary temp gauge at 70c then I'd say all good and don't stress about the factory gauge

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Originally Posted by biggqwesty

If it's blowing heaps of black smoke could it be to rich??
Being an NA we don't have much room at all to move on fuel pump adjustment..
They will blow a little when under load but if your seeing black smoke when cruzing then it's possible to rich and thus causing extra heat in the engine..

Apart from that.
If you trust your secondary temp gauge at 70c then I'd say all good and don't stress about the factory gauge

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Not sure about the factory gauge temperature reading as it seems too low IMO, I rewired it the other day as I thought the earth wire may have been dodgy but that didnt change much. It does move up when factory gauge moves and down when cooler etc so it works in that sense just not confident about which temp reading is accurate really.

In cooler weather its not a worry at all, just with the ambient temperature being so extreme I am just wondering what might be making it run so hot. Might have to locate a Diesel specialist on my travels who could have a look at the pump adjustment...

Factory temp gauges are a very rough guide. And many don't trust em..
One way to check your secondary gauge is to borrow or buy one of those Lazer temp gauges. When up to temp check your radiator hose near where your prope is..

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Originally Posted by biggqwesty

Factory temp gauges are a very rough guide. And many don't trust em..
One way to check your secondary gauge is to borrow or buy one of those Lazer temp gauges. When up to temp check your radiator hose near where your prope is..

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Top idea mate! Just wish I didn't live so far away from the shops haha. 3 weeks wait on any post!
I've read about factory gauges being a bit off the mark. Would a temp reading of the outside of the hose be close enough to the inside coolant temp?

Yea it should be spot on.. may get some slight variations if it's minus temps of blowing a strong wind

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Originally Posted by biggqwesty

Yea it should be spot on.. may get some slight variations if it's minus temps of blowing a strong wind

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That will be a good starting point cheers mate. Would be great if its just a dodgy factory gauge!

I'd still investigate the fuel settings.
If its blowing black smoke all the time it's possibly over fueling. That could be pushing EGT's and that would also increase the engine temp.
But yea start with the Lazer temp gauge.
If it is high then maybe look at a tune.

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Originally Posted by biggqwesty

I'd still investigate the fuel settings.
If its blowing black smoke all the time it's possibly over fueling. That could be pushing EGT's and that would also increase the engine temp.
But yea start with the Lazer temp gauge.
If it is high then maybe look at a tune.

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Thanks mate, yeh I always thought the smoke was a diesel thing, but it seems to smoke quite a lot under load and feels like someone has tried to up the fuel mix to gain more power... Perhaps the poor mans turbo option...

Yea I did when I went 33's.. but not to be. It just loaded it more, more smoke and more fuel used..
Took it back to factory after a few months..

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Originally Posted by biggqwesty

Yea I did when I went 33's.. but not to be. It just loaded it more, more smoke and more fuel used..
Took it back to factory after a few months..

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I will get a diesel mech to look at the fuel! Would try myself but I'm guessing its more of a specialist thing!

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Originally Posted by ashmccormick

I will get a diesel mech to look at the fuel! Would try myself but I'm guessing its more of a specialist thing!

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Yea if you haven't touched it then I'd leave for a specialist.
I only did mine as a trial.

ok Ash, you have several questions that need several different answers

Black smoke - yeppers, its over fueling, so some reason most of the TD42's sold in the Territory & northern WA all had the Injector pump advanced..........( mate used to work at Nissan in Darwin in 80s-90's) not sure of the thought process, but it was to overcome the fuel vaporizing issue some had with the SD33's in the MQ's
have a look at that, as this will not help it with running too hot

aftermarket gauge.
get a decent one - electronic, or even an old mechanical one - either either, sounds like the one you have is cactii to the max

factory gauge
these are really just a "sort of maybe could be temp gauge"
about as accurate as a $2 watch

when the needle is at the mark just before HOT - thats its normal hot running temp - approx 105*C
the hot mark is approx 110*C

when its about 1/2 way - thats a normal running temp in cooler climates

Attachment 62974

as Kallen said, if you can get hold of one of those temp guns and just double check the aftermarket gauge you have, it will help

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Originally Posted by Bigcol

ok Ash, you have several questions that need several different answers

Black smoke - yeppers, its over fueling, so some reason most of the TD42's sold in the Territory & northern WA all had the Injector pump advanced..........( mate used to work at Nissan in Darwin in 80s-90's) not sure of the thought process, but it was to overcome the fuel vaporizing issue some had with the SD33's in the MQ's
have a look at that, as this will not help it with running too hot

aftermarket gauge.
get a decent one - electronic, or even an old mechanical one - either either, sounds like the one you have is cactii to the max

factory gauge
these are really just a "sort of maybe could be temp gauge"
about as accurate as a $2 watch

when the needle is at the mark just before HOT - thats its normal hot running temp - approx 105*C
the hot mark is approx 110*C

when its about 1/2 way - thats a normal running temp in cooler climates

Attachment 62974

as Kallen said, if you can get hold of one of those temp guns and just double check the aftermarket gauge you have, it will help

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Great stuff thanks mate, it looks as though there's a few avenues to head down now. I will look into my gauge temperature and possibly get that replaced and get someone to back off the fuel a little as that might help with heat and economy too.

Cheers for everyones input, good to get an outside perspective on something thats been bugging me for a while!

i've got the opposite problem my needle barely gets off the cold line. got me a new thermostat to replace the what i assume is cut. mine also smokes quite a bit. like personal smoke screen when i floor it. mine isn't gauge issue as i can hold the top and bottom hoses in my hands.

i think mine came from darwin when it was new so i might have to check that timing as well.

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Originally Posted by garett

i've got the opposite problem my needle barely gets off the cold line. got me a new thermostat to replace the what i assume is cut. mine also smokes quite a bit. like personal smoke screen when i floor it. mine isn't gauge issue as i can hold the top and bottom hoses in my hands.

i think mine came from darwin when it was new so i might have to check that timing as well.

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Watch out for the long bolt on the thermostat housing mate! It'll either come out easy, or youll have an intimate weekend with the Mav!

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Originally Posted by ashmccormick

Is the bypass port the hose that joins onto the radiator filler neck from the thermostat housing? Is there a downside to blocking this off? I'm assuming I have everything in place, no leaks or coolant loss.

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The bypass port is inside the thermostat housing. The idea of this port is so the coolant keeps circulating through the engine without going to the rad until there is enough temp for the thermostat to start working. This allows the engine to get to operating temperature quicker. Now the thermostat has 2 parts to it so as the main part opens it blocks off the bypass port to allow full flow through the engine and radiator. So if this port is not being closed by the thermostat them already hot coolant can just keep circulating through the engine.

You can use a welsh plug to block it. Or you could take some measurements to see if the thermostat is long enough to close the port when its open.

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Originally Posted by nissannewby

The bypass port is inside the thermostat housing. The idea of this port is so the coolant keeps circulating through the engine without going to the rad until there is enough temp for the thermostat to start working. This allows the engine to get to operating temperature quicker. Now the thermostat has 2 parts to it so as the main part opens it blocks off the bypass port to allow full flow through the engine and radiator. So if this port is not being closed by the thermostat them already hot coolant can just keep circulating through the engine.

You can use a welsh plug to block it. Or you could take some measurements to see if the thermostat is long enough to close the port when its open.

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Legend! Thanks mate I will have to pull it out and have a look at it to see if its functioning properly!

The thermostat is new and a genuine Nissan one so I just chucked it in without thinking about it. Are there many new thermostats that come defect from factory? Or just not opening fully etc?

Not really mate. Just to much tolerance available. You can modify the thermostat using washers or something similar.

Sorry couldnt be stuffed reading all posts. GQ TD42's were renowned for this. My mates does the exact same thing. 1stly, get a real gauge that gives you figures, not just a hot-cold reading. 2ndly, use Penrite HPR diesel 15 (15W-40) & nothing else. 3rdly, if your water pump was not genuine it's from china no matter what the store told you. I've gone thru 3 water pumps in 2 yrs in my GU TD42 to learn this. Also, is it losing any water? Check the quality of the seal around the radiator cap. If your rad is full alluminium, its prob chinese too & they often have poorly designed cap fittings. Also how old is your clutch? Old mate's overheating issues started shortly before his clutch went & even though he took all the same steps you have, the heating issue seemed to go away when clutch was replaced so I'm thinking minor slippage causing heat transfer & overworking engine.

My 1999 TD42 was always overheating when under pressure up hills or carrying/towing a load and was told by several mechanics it was a fault with this model. Fitted a recon engine/overhauled pump and new clutch at 350,000km and got no improvement. Fitted aftermarket top mount intercooler(pump tuned for intercooler) which improved it a little but still had to keep an eye on temp when under pressure as when the temp started to move it went quick. Fitted a 3 core, 75mm thick aluminium radiator(yes it is Chinese but I got it for $450) and temp only moves above just below half way mark when carrying a ton on back and 2 ton in trailer on a hot day.

I saw Bigcol's photo - 3,250rpm @ 105km/hr. Mine does 2,700rpm @ 100km/hr in 4th gear and 2,300rpm @ 100km/hour in 5th. I'm curious why the big difference.