Strange overheating problem.
 

My 87 4runners 22re has been acting weird lately. I thought it might be the temp overshoot problem but it still overheats when the climate control is on cool. The needle goes up almost to the red then shoots down really fast. Now this sounds like a sticking termostat, but the other day it started to go into the red, then went back to normal. I gave it some gas and the temp needle sort of revved like the tach. Went up then back down. What is going on? I'm not burning any coolant, no milkshake oil, no sweet exhaust so i'm hoping this problem is not a headgasket issue. Any suggestions? Thanks.

It could be your temp gauge sending unit that's on the fritz.

do you have a toyota t stat

http://www.4crawler.com/4x4/CheapTri...tml#Thermostat

where is this located? is it something I can test or do I have to replace it and see if it solved the problem? thanks

Air in the cooling system will have the same symptoms of overshoot.

Check ALL cooling system hoses for leaks, especially the heater hoses behind the engine.

The gauge sending unit on the 22RE is in between the valve cover and the EFI body...locate your t-stat housing, then go straight back...you'll see a single wire harness (typically with a blue or black connector) plugged in. Pull that out, and that's the temp gauge sender right there. Takes a 17mm socket to get it out...you can order a new one from www.rockauto.com for around $20 IIRC or check your local dealership ($$$$$), or auto parts store. Your best bet to get the correct one without emptying your wallet in the process is from Rock Auto though...they had mine to me within 2 days.