Hi,
I just had the timing chain and water pump replaced last week on my 1990 22RE 4x4 Truck, now everytime I started driving my truck for the first 7-10 minutes, the temperature went up to 3/4 HOT, then immediately dropped to normal.

Is that a sign of blown head gasket? or I need the radiator flush?

BTW, the thermostat had just been replaced a month ago. Truck is extremely well care/service.

Thanks

Have you checked the coolant level? What temp thermostat did you install?

you might want to check to make sure theres not oil in your water and water in your oil take oil cap off and look my 89 22re kept going up and down likethat i finally looked and had water in my oil the chain had rubbed a hole in the water pump cover

Did this start after you replaced the t-stat?
And did you use a Toyota or aftermarket one?

TSB: 029032787 22R-E Engine Temperature Overshoot
It says:
Some 1984 pickup trucks and 1983-1984 Celica models, equipped with 22R-E engines, may experience a condition called "temperature gauge overshoot". After starting a cold engine the temperature gauge will indicate a higher than normal engine temperature for a short time just prior to the thermostat opening. After the thermostat opens, the temperature gauge will return to the normal range. A new double valve thermostat has been made available to reduce temperature gauge overshoot.
And calls for part number 90916-03070 which according to the TSB replaces 90916-03055.

It applies to all 22R/RE's actually. And as long as the temp goes right back down to normal, it's no big deal.

[quote=fourwd1]Did this start after you replaced the t-stat?
And did you use a Toyota or aftermarket one?



Yes, it started right after I replaced the timing chain and water pump.
I bought another thermostat fromt NAPA auto part and it didn't help. Oh, well, as long as it doesn't overheat, that doesn't bother me :-)


Thanks everyone for the input.

FYI. I had this problem a while ago, and that bulletin does work. Replaced it with the toyota one, and it all but went away. It was only a few dollars more than an aftermarket one anyhow.