4Runner Overheats

BLAHBLAHYEA

MEMBER
TOYOTA 4RUNNER

I have a 1995 4Runner with 107,000 miles. It is a 6 cylinder 4WD.

The previous owner had the head gaskets repaired. Two years later I had the engine rebuilt.

About a year later it started to overheat and the dealership replaced my radiator. Said it was rusting and clogged.

About 3 months later it started to overheat again. They cleaned the radiator but said it wasn't really clogged. They figured there was a problem with the head gaskets again.

After that the car did not overheat for several months. It is now overheating again.

I'm assuming it's the head gaskets, but could it be anything else? Can you explain why it would run fine after that recent radiator cleaning?

2 Replies

FAIRRACING31

MECHANIC
150 POSTS

You could have a bad thermostat. I would have replaced it when the radiator was done or a head gasket replacment.

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Sunday, October 21st, 2007 AT 8:02 PM

WALTER5550

MEMBER
13 POSTS

Hey there,

Have you tried to figure out what the ambient temperature was when the car was running fine and vice-versa when it was overheating?
If seasonal changes in outside temperatures are significian it could be the reason that the engine runs okay in colder season. I have the same issue with the KZ-TE engine but can reconstruct the case when driving it on the coast in CapeTown (cold ambient temperature and sea level) or in the Kalahari (hot desert climate and 1000 meters altitude).
I don't have a solution yet but keep on experimenting, but realize a few degrees in outside temperature makes the difference.
So the engine runs fine up to say 30 deg C and above it starts to give you trouble.
This might help to localize the symptoms but not to remedy, I would be interested in the solution myself.

Good luck try and error
Walter