overheating problem...Any suggestions?

[jr91X]

I have a 91 ex with 167,000 miles on it. It started overheating 2 years ago and I tried to fix it. Every time that I sit in traffic or go up the mountain roads it would overheat. I have thus far replaced the following parts and still have the problem. New radiator from a 302 with dual 12" electric fans that run on a switch so that I can turn them on any time, new thermostat that opens 5 degrees lower than stock, engine has been flushed and filled with new coolant(50/50), and just to be sure, a new suntune temp gauge. The truck will get to 250 in a heart beat up a hill or in traffic. The only other problem that it has is that overdrive does not work on the tranny. I give up. Any suggestions on what to fix next would be appreciated. :fire:

 

[jimbo74]

tranny is shot or going out... overdrive is the first part to go on the automatics... not too far later, the whole tranny loses all forward motion........

what about water pump?

 

[jr91X]

Sorry...replaced water pump a year and a half ago. Right before that is when the overheating started. say 2 months before.

 

[jr91X]

Also. The overdrive has been like that for over a year. Been waiting until it completely goes before replacing it. Also, at the same time the overdrive went, it slips out of gear if I give it more gas to downshift. It still drives fine though. It is my daily driver and gets me where I need to go.

 

[Glacier991]

I am going to guess that in addition to losing the 3-4 shift because of the solenoid, you also lack TCC lockup maybe. What are your RPM's at 60 mph ?

Over 3000 ?

 

[jr91X]

RPM's at 65 in third are right at 3000. It will go into overdrive on the highway but I cannot give it much gas or the tranny slips. Just cruise. The RPM's there are 2600

 

[Glacier991]

Ok, you MAY have lockup then but maybe not. My thought process at work is this. We will assume the tranny is adding the excess heat to the radiator. Why do trannies get hot? 2 main reasons.... slipping bands/frictions or a non-locked up TC (they can produce a LOT of heat). If you have a slipping OD losing maybe 50-75 rpm in slips, that can also produce a lot of heat. I'd try dropping the pan and cleaning the solenoid screen on the 3/4 solenoid, and also adjusting the band on the OD band and see if that doesn't significantly help. All of this of course, is buying the assumption the trannie is the cause of the excess heat. How's your fan clutch ?

ps at 65MPH I'd expect to see rpm's closer to 2200-2400. I'm yet curious if you have any codes ...

 

[jr91X]

Thanks. I will pull the pan tomorrow. The fan clutch is gone in favor of dual 12" electric fans. Will post a reply whem I look inside. I will use your tranny diary about the a4ld rebuild

 

[Glacier991]

You'll need the gasket pair for the Valve Body.... and a couple cans of brake cleaner, and a new locknut for the band adjusting screw (not a "must" just good insurance against leakage). While you have the VB out you may want to go through it and check everything out. I did a recent thread on that, but it is linked in the Diary.