Mechanics

3.0 L DIESEL TURBO OVERHEATING

1995 Toyota 4Runner

Engine problem 1KZ-TE
1995 Toyota 4Runner 4 cyl Four Wheel Drive Manual 163000 km

I have bought a Japanese import with 1KZ-TE Engine and use it in Botswana at average 1000 m Altitude.
When driving steady on more than 100km/h the engine starts overheating.
I have changed the radiator from 3 core to 4 core to increase coolant capacity which seems to have an adverse effect, also removed the thermostat to increase water flow.
The car has modifications like ARB winch bar, spots and modified bash plate but no engine modifications.
This is a great car but I am disappointed with the problem, specifically in high ambient temperatures (30 deg C+).
I consider to install a safari snorkel to reduce warm air intake from engine compartment, but otherwise I am not sure how to overcome this issue.
Some guys claim to change the turbo to South African Spec's but this is costly and not guaranteed to succeed.
Anybody has some experience how to overcome this problem?
Thanks for your time answering - appreciated
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Walter5550
December 13, 2007.



Removing the t-stat will make it run warmer on a long drive because the coolant doesnt stay in the radiator long enough to be cooled down, it just flows on through and back to the engine.I would start by having it chemical tested for a blown head gasket. Is your custom push bar blocking much of the radiator surface?
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Tiny
Jack42
Dec 13, 2007.
The bull bar is indeed blocking quite a bit of the radiator surface. I have tried out with spoiler to compensate air intake and opened the bonnet at the rear end to allow hot air evacuation as a trial.
For the issue of the blown head gasket, note that I do not have any water leakage or loss during city driving (not over weeks). When water disappears it is through boiling into the expansion tank and this mainly during long drives out of town. There is absolutely no emission from exhaust or sign of watery mix in the engine oil.
Wouldn't a blown head gasket also show the effect when driving in cooler conditions or at sea level? I don't have the symptoms there even if I push the vehicle to 160 km/h over some time, something absolutely unthinkable in higher altitude conditions?

Tiny
Walter5550
Dec 14, 2007.
Have you ever driven it without the bull bar on it? Wondering if this started after that mod or was a problem the entire time. Opening the rear of the hood wont really help, the issue is air getting across the radiator surface not necessarily getting hot air out of the engine compartment. Have you had the cooling system serviced?

Tiny
Jack42
Dec 14, 2007.
I have flushed out the cooling system with the original radiator, then changed to the modified one. What I hear locally is this an issue even without the mod, other guys blew the head gasket on similar vehicles even when no add-ons were done.
Some hints are coming that the turbo has less water throughput than the South African version of the same engine, leading to a higher temperature in the turbo housing. I don't want to experiment this path as I consider it too costly.
It appears that Toyota has also done something on later models as from 1997 they introduced the intercooler.
I have tried to add an after market intercooler but the type did not fit below the radiator housing, trial abandoned.
Question: Would it help to add another radiator, say on top of the bash plate and serie-connect it to the existing one, might need electric fan to operate efficiently?

Tiny
Walter5550
Dec 14, 2007.
I dont think another radiator is the answer or an electric fan for that matter. If it gets hot on the road, it already has air coming at it, a fan wont be able to pull more through, as long as the grille is clear for air to get in.

Tiny
Jack42
Dec 14, 2007.
I was thinking in creating a situation to extend the size of the radiator in the airflow, hence virtually increase the profile. In my opinion we would then pre-cool the hot water on the lower radiator and push it through the main system already cooler.
My experience is that a couple of degrees of ambient temperature already makes a difference, that would mean if we succeed to reduce the intake into the main radiator by 5 degrees it should work.

I have this effect if I switch off the A/C but then run the electric fan in override (I mounted a switch on the dash for this). Of course the whole success is reversed when the A/C comes back into the play, so it is just experimental then who wants to sweat without A/C in 35 degree temperature?

Not sure if it is worth trying.

On another note I have dismantled the IPF spots to see a difference, but absolutely no effect at all despite visually the grille was now clear from obstacles.

Any idea?

Thanks for your great support, we keep on brainstorming.

Tiny
Walter5550
Dec 14, 2007.
If the fan makes a differnece then it isnt getting enough flow across it. Does it have a thermostatic fan clutch?If it does do you ever hear it locking up to pull more air when the engine gets hot?

Tiny
Jack42
Dec 14, 2007.
I think it has that thermo fan clutch, although when you turn the fan blades by hand you feel like viscose resistance. The kick-in for the fan I hear but I am not sure if it is the sound of the electric fan engaging.

I will have to pay special attention as if such a lock set is happening. (Unfortunately this has to be whilst driving at 100 km/h+)

Is there anything that can go wrong with this clutch, meaning what is the triggering mechanism, electrical or thermo mechanical?

If I know I can check out if some connectors are off, could have happened when doing modifications.

Tiny
Walter5550
Dec 15, 2007.
The manual fan is controlled by the amount of heat coming through the radiator. Should be hard to turn when engine is hot

Tiny
Jack42
Dec 15, 2007.
Okay, will do some tests on this. I am still geared to install that safari snorkel, might just make the difference for the few degrees and avoiding to reach boiling point.
Thanks so far for all your good inputs
Best regards
Walter

Tiny
Walter5550
Dec 16, 2007.

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