jhsantacruz63

As the title says, I am having an issue with my engine temp. I have a 1985 Toyota pickup 4x4 with a new 22re. Engine has about 7k miles on it since install and has run great until recently. I took it on a trip up an old fire road to clear brush and make the road accessible again. It was a warm day, about 90F, and the truck did a lot of idling and slow moving up a steep trail. It wasnt hard 4x4, just steep and overgrown. I have an aftermarket temp gauge that I was watching and it never went above 200F so I wasnt to concerned but since then its been running cold anywhere I drive. Usually it would run in the 180-190 range with a 190 t-stat. Currently it is regularly running in the 160-180 range. I had this problem when I first installed the engine but that was because I was given a 160F t-stat, put a 190F in and it ran like a dream. Here is what I have done/checked so far.

-Replaced T-stat with new 190F one. Did not check before installing but Im pretty confident thats not the problem.
-I replaced the TPS sensor with a used one I had that tested good when I installed the new thermostat. Could this cause this temp issue if its not adjusted correctly? I installed and set it up per instructions online and I am confident that it is correct but just wanted to throw that out there.
-Heater produces hot air which made me think that my gauge has gone bad, have a new gauge Im going to try installing today and compare the two. I have been checking the engine/radiator with a infrared heat gun just to make sure its not overheating and its been fine anywhere between 175-195F depending on where I test.
-Another odd thing with the heater, when the heat control is anywhere in the warm zone the temp gauge shows normal operating temp (most of the time) while driving but when I put the temp control all the way to the cold side the engine coolant temp drops 20-40F now. It did do this prior to this problem and even prior to this engine but never this extreme, usually it would drop from 190F to 180F. Is this normal? Could heater hoses be reversed or something?
-Removed clutch fan and drove home one day to see if possibly fan clutch was stuck, (I do have an electric fan tied to a switch in the cab) it ran at normal temp the whole way home (with the e-fan on) and I installed a different fan clutch that was working when removed. Drove to work the next day with it and it was at normal temp until I got off the freeway and onto surface streets then it dropped to 160-170F. Most of the drive I had the heater control partially warm but turned it off shortly before exiting freeway and the temp did the normal drop from 190F to 180F until I got off the freeway.

For reference, I have the 1985 manifold with the two ports for temp probes under the engine intake. I installed my current electric temp probe in the side port and have the top one plugged. My stock temp probe had the prong broken off so I havent bothered to replace it since I have the aftermarket one but figured it would be good to install it where the stock one was. I also have the thermostat housing with a port in it that is plugged currently. Is this a better location for getting coolant temp? The previous owner had one installed there but I removed and plugged it when I installed mine. Has anyone had issues with an aftermarket temp sensor in this location?

I have seen the gauge needle bounce and oscillate occasionally, does this sound like the gauge could be intermittent or failing? When I have checked it with the infrared temp gun, the temp seems to correlate with the gauge when I shoot the sensor, but with its location Im not 100% confident that thats accurate. The gauge I am using is an iequus electric water temp gauge, P/N: 8162.

Any help would be greatly appreciated. Thanks

Terrys87

iTrader: (1)

The factory gauge is not that great on these trucks. One thing you can do is tighten all of the screws on the back of the gauge cluster as they do loosen up and it will help a little bit but not much.

Cleaning the temp sensor located between cylinders 2 and 3 can help with a better reading as that sensor can get some build up on it and give false readings.

The factory fan and fan clutch works great on these trucks when everything is correct. If you are still using the original radiator, you need to take it to a shop that can power wash it as there is a ton of build up inside of them. When they power wash it, you will see what looks like mud and rust come out. I have seen a clean radiator drop the temperture as much a 1/4 on the factory gauge.

coryc85

Could also be air in the system, you want to make sure to burp it really well to get all that air out.

jhsantacruz63

Thanks guys, turns out the temp sender had failed. I am still having the temp drop when the heater temp control is moved to cold, goes from about 190 to 180F. Seems happy and running well, just kinda odd to me. Thanks again