mr.spohn

I have a 1997 toyota 4runner with the 3.4L and it is overheating. i just had the head gaskets replaced and new belts and 2 new thermostats. I still is getting hot. any ideas on what it could be.

4Crawler

iTrader: (3)

When is it overheating? Stopped or slow driving, at high speed, up hills, hot weather or cold? What condition is the radiator in?

mr.spohn

It is normal driving conditions. it doesnt make it too far. but if you shut it down then turn it back on and open heater valve it seems operate nomal temp. the lower hose is always cold when this happens. radiator is near new. like 6 months old.

mr.spohn

is it possible to remove the thermostat completely?

spokane.yota.man

sounds like a thermostat. removing them temporarily wouldn't hurt anything. take them out and run the truck and see if it still overheats. you can test the thermostats by putting them in a pot of water and heating on the stove. when the water reaches the specified temp of the thermostat they should pop open. good luck.

4Crawler

iTrader: (3)

Is it really overheating, as in coolant boiling/overflowing the radiator? Or is it just the gauge running up high? If the latter, might have a look below:
- http://www.4crawler.com/4x4/CheapTri...tml#Thermostat

Usually not a good idea to remove the t-stat on a fuel injected engine. Why? Engine computer will see the engine is cold and try to warm it up with more fuel, but it will never warm up to normal.

spokane.yota.man

i agree 4crawler, the thermostat is there for a reason but running without the t-stat would be no different then starting the truck on a cold day. not the most effecient but won't hurt anything. once t-stat is opened its basically no different then not having it at all. if it has been instantly overheating and it doesn't with the t-stat removed then theres your problem. on my 87 the t-stat would stick all the time in winter and a quick change to the heater controls would cause it to open. if t-stat is bad then it will quicly overheat so i think removing t-stat would be best way to test. or better yet, test them in a pot of water like i suggested.

mr.spohn

it never boiled over or blew anything. it just reads hot on the gauge and a quick ajust of heater controls it is fine. i changed the thermostat 2 times with ones that are not suppose to let you truck over heat. anyways the temp on them is 180. is that maybe to high. maybe a cooler one will work better, like a 145 or 150.

Tofer

toyota's run high t-stats... i would run a 195 in the winter and an 180 in the summer on my 81.

spokane.yota.man

if you use the factory specified thermostat then it shouldn't overheat if everything is working right. using a lower temp t-stat will usually just mask another problem. best to stick with the correct one and to fix what is actually causing the overheating. you said the lower hose was cold when the truck was overheating? thats not right, once the engine is at operating temp then the coolant is continually cycling through the engine and radiator so it should be hot just like the top one. so it sounds like the coolant isn't flowing. either a t-stat isn't opening, something is clogged, or maybe the water pump is bad. those would be my best guesses.

mr.spohn

is it possible that this truck is allergic to aftermarket parts and i need to go to the dealer for the thermostat. the head gasket blew and the truck never once overheated. now it is and i didn't save the old one.

spokane.yota.man

a thermostat is a pretty simple part and i doubt the fact its after market makes a difference. if it works then it works. test it in hot water like i mentioned earlier. then you can be sure.

mr.spohn

thanks for all your help! this small thing has been driving me nutz. i will post the out come later.

mr.spohn

Okay so i have that 1997 4runner that was overheating, well it still is. i took out the thermostat and boiled water on the stove and it opened at 180 like it was suppose too. so back to square one. now what is the likly ness of the water pump not working properly but not making any noise. or leaking?