80 Series Diesel Overheating

Submitted: Monday, Oct 28, 2002 at 01:00
ThreadID: 2238 Views:4048 Replies:9 FollowUps:7
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I have a 1996 GXL Lancruiser with the 1HZ diesel engine, just coming up to 100K km. On a couple of occassions when climbing steep ranges (on road) I have noticed the temperature rise to just under the red. In all other situations the temperature is fine and sits at about half.

I think I may have a problem in the cooling system. What is the best way to narrow down the fault. Can the fan, thermostat, blocked radiator etc be tested.

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Reply By: Member - Ian - Monday, Oct 28, 2002 at 01:00

Monday, Oct 28, 2002 at 01:00
check your fan i remember seeing this problem before on this forum, you should be able to turn your fan by hand and feel a fairly firm restriction if not maybe your viscous coupling is faulty.
im sure if you do a search on here you will find the answer to your problem
AnswerID: 7942

Follow Up By: Derek - Tuesday, Oct 29, 2002 at 01:00

Tuesday, Oct 29, 2002 at 01:00
Ian, Garry may be right. If he is, you can replace the silicon in the viscous coupling. You will need 2 small bottles of the stuff, part # 08816-10001. At 65,000 ks you could assume nothing major is wrong with the cooling system and that it will be something strange causing the problem. The above fix can also be the cure for AC systems that won't quite pull down to cold. Good luck!
FollowupID: 3733

Reply By: ROWDY - Monday, Oct 28, 2002 at 01:00

Monday, Oct 28, 2002 at 01:00
just long shot, but I have seen the impeller on the water pump corroded away with electrolysis, especially when incorrect coolant/water ratios are present. If the radiator has been removed previously and let dry out before refitting a lot of scale forms and this can block the tubes. A couple of my mates have experienced temperature fluctuations on long slow grinds and have fitted thermo fans on a manual switch to overcome the problem but I think it only masks the problem. Hope this has been of some help. rowdy
AnswerID: 7947

Reply By: charl makssi - Monday, Oct 28, 2002 at 01:00

Monday, Oct 28, 2002 at 01:00
greetings garry,

seems to be a common complaint. from my own expreience (gq 4.2 efi) i have had my temp dial read close to the red on two occations and both times the G train was working hard up hill on a warm day, i was concernd at the time but let it go, then upon my return i checked my nissan owners manual and it is within the manufacturers spec as normal range so before you loose your cool and wits check your owners manual it may save a lot of hassel and stress not to mention faith in the cruiser.

regards charl
AnswerID: 7952

Reply By: truckster - Monday, Oct 28, 2002 at 01:00

Monday, Oct 28, 2002 at 01:00
I too have been chasing up an overheating problem for 12months!

I have had the radiator flushed 2 times by radiator places, ended up replacing the radiator with a NEW 3 core, hoses, thermostat, Temp guage sender, Coolant HEAPS of times, and still on long slow climbs it overheats. in the snow the other week it STILL over heated on the long slow climb to the huts, and it was bucketing down snow at the time.. :(

You would be amazed how much of the radiator you **CANT** clean with a hose, the best bet is to remove it from the truck, and clean it out properly. Mine first time was blocked 25% on the outside, I thought hosing it out while on the truck was good enough, but its not.

Then turn it upside down, and stick the hose in what is actually teh lower hose mount, and flush out the radiator that way.

Ive been thru everything, and now about to replace the clutch fan, $300+ and then the only thing left is water pump at $400+!! Oh well if I do ever sort it out, I will have a complete cooling system rebuilt!
Also check out the 80series list, http://www.lcool.org/ they have a technical HELP page.
AnswerID: 7955

Follow Up By: Janset - Monday, Oct 28, 2002 at 01:00

Monday, Oct 28, 2002 at 01:00
Hi truckster.
A simple test and it will eliminate one major component.

Remove the thermostat!

Now put your vehicle in the same conditions as when it over heats and see what happens. If the problem is gone, problem solved. If no change you have eliminated another possibility.

A new thermostat does not necessarily mean it is a good one. In the past and on one occasion it was the third thermostat before I found the good one.

A test can be made by boiling the thermostat in boiling water, but that does not REALLY tell you all as the thermostat opens at a higher temperature when under pressure of the pressurised radiator cap/system.

I believe that the removal test is the best method.

Warning: If this resolves your problem, don't be tempted to run without the thermostat, it is false economy.

FollowupID: 3706

Follow Up By: Truckster - Monday, Oct 28, 2002 at 01:00

Monday, Oct 28, 2002 at 01:00
As you say, the only way to go about it is one at a time, Personally I would start by removing radiator and cleaning out properly, it cant hurt.....

Personally Been there done that.

Did do everything one at a time, this has taken 12 months+ (Oct long weekend last yr!)

I only have 2 things left to change now, Water pump and Clutch fan(which I have sittin in other room :( )
FollowupID: 3710

Reply By: Tony - Tuesday, Oct 29, 2002 at 01:00

Tuesday, Oct 29, 2002 at 01:00
Gary, I to had this problem with my Landcrusier, had the radiator re-cored, new thermostat, and replaced the fluid in the thermo fan (available through Toyota spares). I don't know which of the above was at fault but problem solved.


AnswerID: 7981

Reply By: dave - Tuesday, Oct 29, 2002 at 01:00

Tuesday, Oct 29, 2002 at 01:00
how's this for a chain of events.

Put in a NEW radiator shortly after fitting a turbo ~13 months ago. Had overheating (just under red) a couple of times over last summer. Took the truck back to the radiator place and asked them to check it out.

It seems that they only checked but did not replace the radiator, all fixed, 6 months of heat free motoring.... until last week.

Temp went up, coolant level went down, with the obligatory hissing and steaming. I limped to the nearest radiator place in the chain, had to top the radiator up twice to get there (with the engine running). Two hours later, resoldered top tank and no problems... until this week.

Quick run down the highway, temp started to rise, but not badly. and then the thing that really got me... I stalled the truck, now you know that there is something wrong with a diesel troopy if you can actually get the thing to stall, taken to friendly mechanic, running on 5 of 6 cylinders, guess what, cracked head.

Moral of the story, it odesn't matter how many times you replace, fix things, a 5mm split in a basicly new radiator will still bring you undone in a real hurry.

So the old girls gets a new (recon) 2H, won't know myself, just imagine all that power!!!!???

AnswerID: 7983

Follow Up By: Truckster - Tuesday, Oct 29, 2002 at 01:00

Tuesday, Oct 29, 2002 at 01:00
I too had the problem with a radiator place not only telling me they did all this work, but charging me horrific amounts for it.

10mths later at another radiator place they inform me nothing had been done the first times...

what do ya do...? Complained to the manager of first place he laughed and said do what you like.
FollowupID: 3730

Follow Up By: Dave - Tuesday, Oct 29, 2002 at 01:00

Tuesday, Oct 29, 2002 at 01:00
actually my local radiator guys have been very good, they have refunded me the cost of the radiator repairs.

I guess that it's not their fault that i put cold water into a hot engine.

Any ways, the old girl had done 385 000kms, and the bottom end was starting to show signs of getting old, like needing an extra 5-6 litres of oil in between 5000km services.

Had to happen eventually. guess that is the price you pay for high performance. ;-)

FollowupID: 3732

Reply By: Steve - Tuesday, Oct 29, 2002 at 01:00

Tuesday, Oct 29, 2002 at 01:00
Garry: had similar problem on mine and it turned out to be the Thermo Coupler on the fan... eliminated all other problems by replacing eveything else !! Cost a bit, and found everything else was in perfect condition !! Toyota dealer was as useless as you wouldn't believe... this all happened while on a long trip, so I couldn't get back to have a bite of him ! ( I replaced the whole unit !!)
AnswerID: 7995

Follow Up By: Garry - Wednesday, Oct 30, 2002 at 01:00

Wednesday, Oct 30, 2002 at 01:00
Thanks Steve

I think I'll do the coupling fluid in the fan and get the radiatopr flushed. But the fan feels OK, some slight resistance when I turn it.

Does anyone know if there is a good way to check the proper operation of the fan?
FollowupID: 3755

Reply By: Legend - Thursday, Oct 31, 2002 at 01:00

Thursday, Oct 31, 2002 at 01:00
ten dollars or so invested in a new radiator cap wouldn't go astray either guys. Sounds simple but that and a new thermostat solved a lot of my problems earlier this year.
AnswerID: 8048

Follow Up By: Steve - Thursday, Oct 31, 2002 at 01:00

Thursday, Oct 31, 2002 at 01:00
Garry: haven't met and have no idea how anyone can 'test' the unit .. it all seems to be a shakey feely thing ! If it spins one way or the other etc.. all a bit hit and miss and I reckon my engine is worth more than that. The Toyota Dealer i used didn't know either ... As for all other parts that were replaced, nothing could be faulted with them and thay all look as the day they went in !! (after 150,000kms) Some reckon you can put in oil etc..? Save money ?
FollowupID: 3795

Reply By: wherethefugawi - Friday, Nov 29, 2002 at 01:00

Friday, Nov 29, 2002 at 01:00
I have 100 series just coming up to 48 months old and have just started (3 weeks ago) having temperature problems on warm to hot days at speed. At low speeds all okay
Thermostat and fluid in fan changed but did not correct problem.
Radiator removed (today 29/11/02) and top tank removed ..cores blocked with a sediment of somesorts??? Natrad Specialist cannot get a tube cleaner though tubes to remove residue.
Car has been serviced in accordance with Toyotas Schedule and requirements ( at least that is what I had booked it in for)

Heater core gave up the ghost 2 months ago. Could these two items be related?

Could this be your problem also?
AnswerID: 9114

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