All, I have a 1996 4Runner 6cyl I am experienceing overheating issues. While I am at normal operating level and am ideling the air from my heater is cool once I step on the gas it heats up. After idel for 30 minutes air is still cool (Heater is on full and Hi) any suggestions, once I drive it heats up but there should be some level of heat. NOTE : fluids are full, could it be that there is air in the line and that it needs to be burped?

 

Just to get clarification, you said you are overheating (i.e. engine temperature guage in or near the red zone) and you don't get hot air from your heater? If both of those are true, it could be a combination of problems.

If your engine is overheating, it could be air in the system (not likely unless you just had coolant replaced, or you recently had to top up your coolant because of a leak), or it could be a faulty thermostat or water pump.

Now, when your engine is overheating, at least then you should be getting hot air from your vents unless your heater valve is not opening or your heater core is plugged. Try checking both your heater lines where they go through your firewall (top center of your engine compartment). Both of these lines should be hot when your heater is full on (and your engine is hot). If not, check the operation of your heater valve. If it is opening fully, you may have a plugged heater core.

Air in the system could cause both problems to happen simultaneously. (Overheating and no heat). But again, If the problem just showed up on it's own (i.e. without any maintenance being done on the system), and you don't have any indication of your cooling system level having been low recently, then I would question how the air got into your system in the first place.

I you have no heat and the engine is not overheating, I would suspect thermostat not closing when it should (so your coolant is always flowing through the radiator and never gets up to operating temperature).

Good luck.

 

I would suspect the water pump. Sounds like there is a lot of blow by - at idle there is not enough pressure to pump the water through the heater core so you feel heat, but there is if you give it a little throttle. Just my guess ....

How many miles, and when were the timing belt and/or water pump replaced?