My buddy has a 1993 4runner 3.0 auto. Last summer he removed the thermostat due to overheating. Today he put a new thermostat in and after the motor warmed up the 4runner started over heating as it did just prior to removing the thermostat last summer. Anybody have any ideas. btw he bought his thermostat from Napa.

 

What temp is the T-stat rated at? Also only buy T-stats with the lil bypass nipple (or atleast one tiny hole drilled in it) .. This is critical since it allows some fluid to get past and get the wax heating up properly.

I've fought T-stats many times and this simple lil thing makes all the difference.

 

I will tell him to buy one from Toyota tomorrow. He did mention that there is no bypass nipple or hole. Without that bypass, the 4runner will overheat that fast?

 

It shouldn't under normal conditions because the hot coolant from the oil cooler dumps straight onto the t-stat on the 3vz. I've heard the jiggle valve is mainly for helping drain the block, he could just drill a small hole near the edge of the t-stat. Some say the jiggle valve is to also help in getting the air out of the system. Now the 22re engine is a different story.

 

Well according to him, when he first got the 4runner, the previous owner did head gasket, timing belt waterpump and t-stat, however shortly after he got it the overheating started. He removed the t-stat and drove it for severl months without it with no problems. Now that winter is here, he is not getting enough heat. However, by replacing the t-stat the 4runner is back to overheating. Is there something else other than a t-stat that could be contributing to this?

 

Maybe this is a silly question, but is he putting the t-stat in correctly as opposed to backwards?

I've been using NAPA and/or O'Reilly t-stats for years with no problems......incidentally. What I'm saying is the brand isn't the problem.

 

I'll double check with him, but I always thought it would only fit in one way.

 

Nope. People have put them in backwards. Not me, of course....

 

I was just thinking, if one was to mistakenly buy a water pump for a manual, will it install into the auto. Reason why I am asking is because when I did my brother in law's timing belt and water pump we bought a water pump from Kragens and it turned out to be for a manual. We ended up buying it at Toyota. My friend doesn't know where the guy got his from. So my only thought right now is that maybe the wrong water pump is in there.

 

Maybe this will help?

http://personal.utulsa.edu/~nathan-b...10thermost.pdf

 

I didn't know there was a different one for auto's and manny's. The FSM doesn't specify a difference. I've never had a manual tranny/3vze combo, so I couldn't tell you definitely. I have an automatic. Doesn't hurt to make sure, I suppose.

 

My brother in law and I just happened to see a little variation from the one we pulled out and called Toyota and they infact had a different part number for an auto vs a manual.

 

Weird. I will have to look into that myself. Thanks.

 

That's interesting, the auto does have more stress on the cooling system because of the auto tranny cooler in the radiator. Maybe Toyota engineers put a higher flow water pump in the autos, very interesting. Were the pump blades bigger on the one you took out?

 

unfortunately I don' remember, it was a year ago when we did this.

 

I just got off the phone with Toyota, yes there is a different pump. There is an additional spout on one. If you buy the one with the additional spout and yours didn't have it, you could still use it as long as you cap it off. So I guess that eliminates that as being a problem for us.

Anyone esle have any ideas on the possible problem here?

 

I know the answer to your problem. The head gasket of the left side is on the right side and the right side on the left. Some of the water holes in the gasket are blocked. you have to change the head gasket. I had that problem two years ago. The mechnic who changed the HG should be responsible for that.
Guy.

 

That does make sense, but with that being said the 4runner runs fine without a t-stat. If the head gaskets were on wrong, wouldn't it still run hot? I will run this by my friend though. Thanks.

 

You might be on to something here, I talked to my buddy and he told be that the head gasket was done after he bought. the guy he bought it from replaced the head gasket and then the overheating problem occured. He will be talking to the guy tomorrow to get him to fix it. Thanks again Starik.