My 89 3.0 V6 4Runner is having some issues overheating. It is not consistent. When pulling a trailer or idling for a long period of time is when it overheats the most. If I turn the heater on it helps to bring it down. It will usually cycle back down eventually either way.

I have changed the thermostat. I have tried bleeding the air out of the system. Bleeding the air helped a lot but it still overheats, just takes longer.

Any suggestions???

I personally think it is still having an air void issue but can't seem to get it all out.

Thanks for any help!!!

 

I know what I would do.....if your's is an auto, I'd bypass the radiator and get a large tranny cooler. I would also replace the radiator especially if it has 200k miles on it.
I'd make sure the oem fan shroud is still there.....if it has electric aftermarket fans I'd switch back to oem.
One more thing I would do for sure......The factory water temp gauge is not helping you......I'd add in an aftermarket one that has a large dial...easy to read temps.

 

Thank you for the suggestions. I rebuilt the motor at 270K and it is running great. However, the radiator is the original. It is a 5 speed tranny. It has the original OEM fan and shroud...all good. I really like the gauge suggestion. I think I'll start there.

I took it out for a long drive last night. It did great until I set in a drive through for about ten minutes. Started to heat up but as soon as I was back on the road it dropped back down below the mid point.

Thanks again!

 

You really should get one of these

http://www.sunbeltradiators.com/rloo.../3.0L/Radiator

 

Thinking about it.....sounds like you have an airflow issue.....bad fan clutch?

Replacing a radiator with 270k on it is good preventative maintenance......

 

I think you may be spot on with the fan clutch...I never thought of it. Thanks for the link on the radiator as well, great prices!

Really appreciate the help!

 

[QUOTE=ZUK;52326801]Thinking about it.....sounds like you have an airflow issue.....bad fan clutch?

Thank you ZUK! You were absolutely right about the fan clutch. Replaced it earlier and took it for a long drive. Let it set idle multiple times for extended periods each time. Temp gauge didn't budge!!!

I would not have thought of the fan clutch. It appeared good except for the thermostat on the back of the clutch. It looked like it has probably been stuck for a while.

Thanks again!!!

 

They can get worn out with age and act up. When mine went out it would only over heat after long periods of sitting and running. The old owner had put a new radiator in it thinking that was the issue. This is a very common issue on the 4.0 jeeps as well and is often misdiagnosed as a bad radiator or blown head gasket.