My 94 3.0 5spd 4runner usually pumps out good heat through the vents... in the summer it would burn my feet when wearing sandals. Its just started to get cold and the heat will fluctuate from hot to nearly no heat at all. The engine temp stays constant where it has always been, just around the middle.

Any ideas or common problems? I am planning to flush the cooling system, I'm not sure maybe a clogged heater core.. Just wondering if anyone else has had similar issues and what fixed it for them.

Tim.

 

Might also check out the thermostat, it may be sticking. Also make sure to get all the air out of the system, perhaps drilling a hole on the t-stat flange to let air get through:

http://www.4crawler.com/4x4/CheapTri...tml#Thermostat <= Corrected link

 

its a 3.0 v6 not a 22re

 

Yes, understood. Was only pointing to the page for the general info on the t-stat, not for the specific part numbers.

 

oh okay.. I havent seen any change in engine temp so I dont think its related to the t stat but i gotta check everything.

 

Easy enough to check it out in a pot of hot water on the stove with a thermometer. Also, if you hear any gurling or whooshing sounds when you rev the engine w/ the heater valve open, you may either have air trapped in the system or it might be a sign of a leaking head gasket. Air or exhaust gas rises to the highest point in the cooling system, which is usually the heater valve and heater core and air will not transfer as much heat as liquid does. Lack of heater output was always my first sign of a head gasket failuer on my '85. A cooling system pressure test could help detect this sort of problem or you can do a simple chemical test to rule out exhaust gas contamination:

http://www.arrowheadradiator.com/hea..._leak_test.htm

 

I had the exact same problem. The linkage (behind the dash towards the bottom) that opens and closes a coolant valve via the temp switch had broken off. The valve is very easy to move and could do so on it's own (varying the heater temp). I just rigged it open with a zip tie. It's worth lookin'. I have a pic of the problem here (post #10)