GQ1989 TD4.2 Overheating under load.

[Old Fisho]

Hello all,
This is my first attempt at a thread and to get some help/ideas from you the members. Have already read thru a lot of threads and have some ideas to follow up. Will try to be as brief as possible without leaving out critical bits. Here goes.
1989 GQ TD4.2/2 with aftermarket Schwitzer turbo. Overheats under load. Actually boils the coolant. Owned this for quite a few years now, but never towed boat or van in hot weather until last summer.
Was even overheating on 30c plus days with aircon turned on and not towing a load. Fixed by getting the thermo fan (aircon fan-not the main clutch fan) to actually work. Can now run the aircon but yet to test on really hot day.
When towing 5m fibreglass boat with big old 115hp merc she overheats when climbing what could be described as piddling little hill. Same thing if towing pop top van and lots of camping junk. On freeway she struggles to get over 105ks and I settle for a comfortable throttle rather than pushing it. But inevitably when she is under load (bit more throttle) up a slope (not hill) she boils up.
I know these old girls are not the bigggest most powerful things invented, but I expected a bit better. The weight of the boat or loaded van wouldn't be near what some people drag around.
So far;
Radiator flushed and whilst worth the time they say it was not the problem.
Water pump checked after gasket blew. Looked OK to me, but my qualifications could be questionable. (Have managed to pull a few old donks down and put them back together in my younger days..but am not a mechanic)
Thermostat renewed.
Water flow appears good.
Belts tight but not stressed.
2.5" exhaust...have read 3'' would be better. Is it, would it on my setup??
Clutch fan feels firm not loose. Tightens a little, I think, when hot. Not sure though, and can see a little oil sweat around it. Not dripping leaks, but dust coated. So will be taking it off for a closer look anyway.

The Schwitzer turbo appears to be oil cooled/lubricated. The cooler sits in front of the aircon radiator which in turn is in front of the water radiator. The aircon thermo fan sits in front of the aircon radiator (naturally) and you have to wonder how much cool air ever reaches the water radiator.

Noted some threads about bonnet mods. Not keen on that idea. All shrouds are in place.

Recently drove a GU 2.8 turbo and noted a distinctive "kicking in" of the turbo when I put the boot in going up hill. Never get this with mine. It's like my turbo is either not working, working all the time, or just a very smoothe transition in speed and power (told the missus it works like me). mmm probably bs.

A young bloke in Albury 4wd shop advised it could be like one he had, and needs to be de-tuned a bit to reduce the fuel input under power. He recommends Denco in Wagga. Spoke to them and they were helpful and willing to look at it, confirming what the young bloke said but added it may not be that at all.

They are my next stop after clutch fan.

Sorry about the lengthy story, but hope it paints a better picture and saves you all time in asking me the obvious.

Any ideas and help is very welcome.

Regards Dick (Old Fisho)

[Bigrig]

Hey mate - top job on the description. Quick one from me, but relevant as I just had the same problem with overheating. I too had the radiator and the whole cooling system flushed and apparently it wasn't too bad, but even so it is fairly old and starting to struggle to cool things down (they still deteriorate even though they look ok) - first port of call after that was replacing the thermostat with a colder one (you said you replaced yours, but what with?? - the one I put in opens at a colder temperature and hence keeps cooler water from the radiator constantly moving through the system, and the water going back in is not as hot as it previously was).. The thermostat definitely helped things but it is still heating up but only on really steep inclines and/or under load (recent trip to Goomburra pulling about 3.5 tonne in total up Cunninghams Gap in the Great Divide) ... next step for me is an alloy radiator, new, and far more efficient at cooling. Obviously only the radiator side of things from me as I have just experienced it, but others on here will pass on some more knowledge regarding the other items.
Scotty

[Finly Owner]

some basic ideas, the coolers, are they free of debri in their cores, not blocking air flow to radiator, do you have big spotties blocking air flow(think you said not when talking about lights). Is your coolant the correct stuff? not watered down crap, but good quality coolant.

Tim

[Old Fisho]

Hey mate - top job on the description. Quick one from me, but relevant as I just had the same problem with overheating. I too had the radiator and the whole cooling system flushed and apparently it wasn't too bad, but even so it is fairly old and starting to struggle to cool things down (they still deteriorate even though they look ok) - first port of call after that was replacing the thermostat with a colder one (you said you replaced yours, but what with?? - the one I put in opens at a colder temperature and hence keeps cooler water from the radiator constantly moving through the system, and the water going back in is not as hot as it previously was).. The thermostat definitely helped things but it is still heating up but only on really steep inclines and/or under load (recent trip to Goomburra pulling about 3.5 tonne in total up Cunninghams Gap in the Great Divide) ... next step for me is an alloy radiator, new, and far more efficient at cooling. Obviously only the radiator side of things from me as I have just experienced it, but others on here will pass on some more knowledge regarding the other items.
Scotty
Thanks Scoty,
My rad cap is standard temp/pressure but not original Nissan. Purch from Bursons. Will definitely look for cooler as you suggest. Can you get them from any old auto shop or speciality 4wd outlets only?
Thanks for the reply Scotty.

[Old Fisho]

some basic ideas, the coolers, are they free of debri in their cores, not blocking air flow to radiator, do you have big spotties blocking air flow(think you said not when talking about lights). Is your coolant the correct stuff? not watered down crap, but good quality coolant.

Tim

G'Day Tim,
Thanks for the post. The radiator core is clear and had a very recent clean out and test inside and out by local rad man. The turbo oil cooler core is clean. The aircon is as clean as a strong airblast will get it whilst still in the vehicle. ie probably nowhere near real clean. Have been reluctant to remove due to gas escape etc. Might have to bite the bullet though.
The coolant has been new good stuff at 30% inclusion. Renewed a couple of times after boiling and water pump gasket blew. Renewed again by rad man recently, so it has been eliminated as cause since.
Don't have spotties or other airblockers in front of grill.
I guess I wanted to believe the aircon core is clean. But you have applied the thumbscrews. best get off my lazy b and have a proper look.
You have caused this old man some mental torment, but I thank you in anycase.
regards Dick

[Bigrig]

Thanks Scoty,
My rad cap is standard temp/pressure but not original Nissan. Purch from Bursons. Will definitely look for cooler as you suggest. Can you get them from any old auto shop or speciality 4wd outlets only?
Thanks for the reply Scotty.

Not sure where mate, to be honest - the mechanic sorted me out on that one - but just a note that the only reason I am suggesting to do this is due to the age of the car - for some reason with electronics and such, it is not recommended to change the operating temperature of newer vehicles as it puts the computer out of whack. I think the temperature difference is not that great between a normal and cold thermostat (about 15 or so degrees celcius) which still keeps the engine up there in normal temperature range, but a colder thermostat lets the cooling system work that much easier, and hence reduce chance of over heating. My only concern for your truck would be the variance in summer/winter temperature (i.e. bloody cold in winter, bloody hot in summer) ... less of a variation up here in QLD, so have a chat to your mechanic about it, as the last thing you want to do is have to change the thermostat back and forth based on the season. Tony, Tim and crew are far better at this than me mate, so they'll guide you no doubt - just thought I'd offer my two cents worth as I had the same problem on my 92 GQ. All the very best with sorting it out.

[Old Fisho]

Not sure where mate, to be honest - the mechanic sorted me out on that one - but just a note that the only reason I am suggesting to do this is due to the age of the car - for some reason with electronics and such, it is not recommended to change the operating temperature of newer vehicles as it puts the computer out of whack. I think the temperature difference is not that great between a normal and cold thermostat (about 15 or so degrees celcius) which still keeps the engine up there in normal temperature range, but a colder thermostat lets the cooling system work that much easier, and hence reduce chance of over heating. My only concern for your truck would be the variance in summer/winter temperature (i.e. bloody cold in winter, bloody hot in summer) ... less of a variation up here in QLD, so have a chat to your mechanic about it, as the last thing you want to do is have to change the thermostat back and forth based on the season. Tony, Tim and crew are far better at this than me mate, so they'll guide you no doubt - just thought I'd offer my two cents worth as I had the same problem on my 92 GQ. All the very best with sorting it out.
OK mate, understood and appreciated.
Regards
Dick

[tkn]

Tim,
May be worth checking your injection timing. If its retarded that will give you the sort of problems you have talked about i.e. lack of power, overheating, etc. On the other hand, if it is way too far advanced you might get similar. If the Patrol has the right radiator and it has been properly flushed, it possible that the cooling system is not the main problem. A TD42 with properly adjusted turbo should give you loads of power. Just two further thoughts 1. renew the fuel filter on the lift pump and 2. check the small stainless steel gauze filter in the banjo coupling of the fuel line into the injector pump.

[Old Fisho]

Tim,
May be worth checking your injection timing. If its retarded that will give you the sort of problems you have talked about i.e. lack of power, overheating, etc. On the other hand, if it is way too far advanced you might get similar. If the Patrol has the right radiator and it has been properly flushed, it possible that the cooling system is not the main problem. A TD42 with properly adjusted turbo should give you loads of power. Just two further thoughts 1. renew the fuel filter on the lift pump and 2. check the small stainless steel gauze filter in the banjo coupling of the fuel line into the injector pump.

Thanks Tim,
Will add these to my list. The fuel pump was overhauled a month or so ago after it had started leaking, that should mean the filter on the pump was renewed . . maybe.
Regards
Dick

[MudRunnerTD]

Hey Fish,

Get it on the Dyno mate, who fitted the Turbo? did they tune it on the Dyno?

Have you got any after market gauges fitted? ie, a Turbo Boost gauge and a Pyro Gauge? Fitting these gauges will change the way you drive mate and give you REAL feedback for what you motor is doing second by second. Especially the Pyro.

Personally mate it sounds like your TD42 is tuned to crap mate. THE ONLY WAY to tune that engine and get it right is on a Dyno and do a few runs. It will be the best money you spend on it and it should be the next thing you do before chasing cooling probs that might not even be there.

A good Dyno tuner should be able to set your car up with the maximum boost possible tuned to the best Fuel delivery level matched to a Max Exhaust temp of around 550.

Your Problem then will be to drive it taking into consideration how the thing actually makes it power and a Pyro will help you figure that out.

Spend your money here = >

Adjustable Boost Controller to allow the tuner to TUNE your Car
Pyro gauge to keep an eye on it once its tuned
A day on the Dyno for a real tune. (This is not a "Dyno run" to compare numbers with ya mates....fark that. Its to sort your car out mate.) Like taking it to a specialist instead of the local bulk biller.

Good Luck.

[Ben-e-boy]

I agree with mudrunner. Get a tune and a pyro. You learn to drive off your pyro gauge, I didnt quite understand how when I was told but when it was installed I noticed that you up the turbo temp by 150- 200 degrees before the water temp gauge does anything. The mechanic told me that 400 degrees is the safe maximum(to get 400 degrees you still need to give it a bit) and 550 degrees for more than a minute can lead to engine failure,
In my opinion a pyro is an essential, not an accessory

Also sludge buildup in the engine can also effect the oils cooling and lubricating ability, you can take the rockercover off and look for sludge deposits in the wells of the head, If you find sludge its possible that the rest of the engine is dirty and will need to be flushed

Cheers
Ben

[Old Fisho]

Hey Fish,

Get it on the Dyno mate, who fitted the Turbo? did they tune it on the Dyno?

Have you got any after market gauges fitted? ie, a Turbo Boost gauge and a Pyro Gauge? Fitting these gauges will change the way you drive mate and give you REAL feedback for what you motor is doing second by second. Especially the Pyro.

Personally mate it sounds like your TD42 is tuned to crap mate. THE ONLY WAY to tune that engine and get it right is on a Dyno and do a few runs. It will be the best money you spend on it and it should be the next thing you do before chasing cooling probs that might not even be there.

A good Dyno tuner should be able to set your car up with the maximum boost possible tuned to the best Fuel delivery level matched to a Max Exhaust temp of around 550.

Your Problem then will be to drive it taking into consideration how the thing actually makes it power and a Pyro will help you figure that out.

Spend your money here = >

Adjustable Boost Controller to allow the tuner to TUNE your Car
Pyro gauge to keep an eye on it once its tuned
A day on the Dyno for a real tune. (This is not a "Dyno run" to compare numbers with ya mates....fark that. Its to sort your car out mate.) Like taking it to a specialist instead of the local bulk biller.

Good Luck.

Thanks Mudrunner,
No idea who fitted the turbo into the GQ. I didn't even know it was an aftermarket turbo when I bought the Patrol. It had four wheel drive (my first) and it looked tuff which is what I want for highland fishing.
I'll take your advice.
I was booking her in for a tune this week. It might have an adjustable boost controller for all I know. But there is nothing inside the cabin and nothing obvious under the hood, so I'm guessing not. Will look around for one before taking to Wagga for a tune.
No gauges in her at all(other than standard of course). Will take a look around for a Pyro.
Thanks for taking the time buddy.
Regards for now.

[Old Fisho]

I agree with mudrunner. Get a tune and a pyro. You learn to drive off your pyro gauge, I didnt quite understand how when I was told but when it was installed I noticed that you up the turbo temp by 150- 200 degrees before the water temp gauge does anything. The mechanic told me that 400 degrees is the safe maximum(to get 400 degrees you still need to give it a bit) and 550 degrees for more than a minute can lead to engine failure,
In my opinion a pyro is an essential, not an accessory

Also sludge buildup in the engine can also effect the oils cooling and lubricating ability, you can take the rockercover off and look for sludge deposits in the wells of the head, If you find sludge its possible that the rest of the engine is dirty and will need to be flushed

Cheers
Ben

Thanks Ben,
Sounds like good avice that I can add to my list. I might get to know my Nissan by the time I get thru this.

[justrocho]

you say you had the pump done. did they set the fuel to suit the turbo. i tuned mine by fueling up for power and then increase boost to bring the egt down to acceptable temp. dyno time

[Old Fisho]

you say you had the pump done. did they set the fuel to suit the turbo. i tuned mine by fueling up for power and then increase boost to bring the egt down to acceptable temp. dyno time

Thanks Justrocho,
The pump was overhauled locally, but I doubt they will recall or bother to tell me the truth about how well they tuned things once re-installed. However, having said that, the heating problem was there before the pump was done.
I will get the gauges mudrunner and others have recommended and then a tune up.
I cleaned the aircon core the other day and removed the Nissan badge from the grill. The badge was covering 20% of the oil cooler. The Thermo fan had a heap of junk packed into the core behind it, and so too did the oil cooler. Had at that stage hoped (fingers were crossed) that the aircon core might have been the heating issue. But I went for a drive later with the Jaco van on and whilst there was a distinct improvement she still, very slowly, worked her way up to hotter than acceptable. The day was only 32c and the load in the car was minus 300kg with no boat on the roof so the difference between cleaner aircon core and when she boild last summer was not a lot....so it's looking like a few gauges and a tune (or de-tune) might be next. Althougn I am still contemplating a new fan clutch I have a feeling it is going to be the same story as the aircon core....a bit of help but not the anwer.
Thanks for taking the time to help anyway, much appreciated.
Dick