My 1994 22re comes up to temperature fine. Then, after about 5-6 miles the guage slowly creeps up to nearly the red, hovers there about 5 seconds, then quickly goes back to normal. It only does this in cold weather (when the heater is on). The heater will run you out. It doesn't do it in the summer with the air on. After it returns to normal, it will stay there. I replaced the head gasket, timing chain, and cover, and thermostat about 5,000 miles ago(135,000 miles currently). It did this before and after the HG replacement. Any Ideas?

 

Even though you have replaced the T-stat, it still sounds like its sticking closed. Maybe get a two stage T-stat. or dont turn the heat up all the way until it gets to operating temp and you have driven the 5-6 miles.

 

Did you get it full? With it cool remove the cap,add water if needed, crank and let warm up till thermostat opens you will see the water level go down or just start to flow thru the radiator. If it sucks down add water and let the t-stat cycle again until it just flows and stops as the t-stat opens and closes.

 

Being from AK, you should know you gotta have heat! Even if I put the temperature selector in the middle, it still does it. When I replaced the T-stat, I checked the old one under the hot water tap, and it actually worked fine. It was an $8 attempt to fix it, but it didn't work.

 

That is normal with after market thermostats. The 22RE throws the heater lines directly on top of the thermostat. So, even when the engine is warming up, the heater lines take longer and is still throwing cooler coolant onto the thermostat keeping it from opening until everything is up to temp.

The fix is the dual zone thermostat from Toyota.

Copy and pasted off of Pirate4x4's FAQ:

"Thermostat Problem

Question: “Why does my engine temp go all the way up to the red before it comes back down to the middle of the gauge after I start it up in the morning. It only does this when the engine is cold and once it warms up it seems to operate normally. Could it be as simple as a stuck thermostat?”

Answer: (From Roger Brown’s Web Site - http://4crawler.cruiserpages.com/4x4...tml#Thermostat)

“What happens on the 22R and 22RE engine, when the coolant goes through the heater core it gets cooled off enough that when it gets dumped back in on top of the t-stat it shuts it. Therefore the temperature in the engine continues to go up. The t-stat that I have mentioned has two valves in it, one at the regular temp. and one smaller on at a cooler temp. If the cool water shuts the big one, the smaller one stays open. All this happens because of the lack of a by-pass hose, which on other systems, keeps hot coolant running on the t-stat.”

You can get the two-stage thermostat mentioned above from your local Toyota Dealer.
Part Number: #90916-03070 "

 

It makes perfect sense now. This is the coolest web site ever! You guys are the best!

 

Haha. Yeah i know about heat. But I also have a high cold tolerance. Mine will do the same thing sometimes, but I see it coming so I push the heat down from all the way hot to the middle of the hot side, put the fan on low and slow down 5mph and it stops right away and wont start again. It hasn't done it since I put a new radiator in though (~2 weeks). Mine seems to only mess up in the spring and fall though.
About yours, I would do what dbcx said. Purge the coolant system of air. Maybe make sure the coolant/water ratio is correct for the temperature outside. After that...I have no idea....

 

Would it be possible to plumb in a by-pass hose?

 

See below for a full description and several solutions:
- http://www.4crawler.com/4x4/CheapTri...tml#Thermostat