my 98 was heating up this afternoon. i know its 94 out and i had the AC on and was driving in bumper to bumper traffic, but the needle was 1/4" away from the red zone. i checked and there was fluid in the reservoir, i dont think im losing it anywhere. is it because of the weather and AC use?

 

yes, turn off the A/C and suffer a little until the traffic is moving at a reasonable speed.

 

but this never happened to me before. is my thermostat going bad? radiator?

 

it shoudlnt be.....that has happened in every car ive ever been in that was sitting still, or moving slow with A/C goin in the heat.....Electric fan(s) would help, because you could turn them on high and keep the air flowing even at low speeds. But i dont think anything is wrong with ur truck IMO.

 

I think there's something wrong, that shouldn't happen. I'm pretty sure not every car in phoenix has to shut off their AC and turn the heater on when stuck in stop and go traffic.

Don't know what's wrong, good luck.

 

didnt say anything about turning on heat......What happens is the fan slows down because the car is moving slow, and is not pulling enough fresh air into the engine compartment. I dont know if he means he is like moving like 2 ft and stopping or just getting stopped alot. The A/C definatley doesnt help keep the engine cool, i know that for sure.

 

Turning on the heater isn't the point. The point is the engine shouldn't overheat in stop and go traffic regardless of whether the AC is on or not. None of my cars have ever overheated in stop and go traffic with the AC on.

 

maybe u have special cars.......thats the way its always been here.

 

Where do you think the heat goes from inside? back out under the hood somewhere right? Go outside, leave ur car running with the AC on, and dont move it, and see if it happens.

 

I do that all the time. The temp gauge is rock solid, never moves.

 

well, we still havent came to a solution for his problem......I dont even use my A/C cause i dont wanna waste the gas or the power. I dont know why ur truck doesnt overheat, but i know that my moms car does, and other cars we have driven have began to run hot, when using the A/C when not moving, for an extended period of time.

 

when did you have the cooing system flushed last??? How old is the thermostat???

 

I'm not sure what type of fan your rad uses but maybe it's not moving enough air at idle. My stock clutch fan moves a ton of air at idle when the engine is hot.

 

Cool. To be fair, the only time my 12 year old truck overheats is when I'm climbing a steep grade in 100 deg weather. But even that's not normal because it never did that when new. I'm still trying to figure it out.

 

Look where I live, and I have NEVER had this happen in (5) 5VZFE powered vehicles - ever. And I have run both mechanical and electric fans.

The thermostat is easy to replace IMO. It could also be a bad sending unit or the radiator cap, or the radiator itself. Have the system pressure tested if you can. NAPA has a good deal on thermostats and seals...shouldn't be more than $15. Then get GM Dexcool from Walmart and some distilled water for $10.50.

 

i flushed the cooling system myself last summer. maybe its time to do it again? the radiator and the thermostat are still original.

 

Let the engine get to norm operating temp, shut it off, and see if you can spin the fan by hand. You shouldn't be able to.

 

Thousands of vehicles a day make a long, arduous, bumper-to-bumper, and very freakin miserable commute home here in the sweltering summer temps of Phoenix and the surrounding suburbs. There are vehicles that over heat in these 110+ degree temps, but most of us do this successfully every day with the A/C blowing full blast. Those with their windows rolled down are driving sub-par vehicles with no A/C or cooling systems that need maintenance.

Any properly functioning cooling system in a '98 4Runner should have no problems blasting the A/C in these conditions in bumper-to-bumper traffic. That said, those of us who have to deal with these extreme temps are in crisis mode when the A/C stops working and I've had more than my fair share of issues with my '95 4Runner. Based on your description, it could be a number of things but I'd be inclined to look first at your fan clutch, especially if you're not losing any coolant.

So first things first -- let it cool down, then pop the radiator cap to see if it is low (even a little) in coolant. If not, definitely do the fan clutch test. If so, top it off and test drive it in the same conditions you experienced over heating. If the problem occurs again, let it cool down and check the coolant level, and if it's low again, you have some reason for concern and you'll need to find out where the coolant is going. If you have no visible leaks, this may be bad news.

Most importantly, what ever you do -- don't let that needle creep into the red.

Ed

 

No-one mentioned this but my first and last time my tacoma came close to overheating was because I was climbing a super steep hillclimb, in 4-low. I checked everything out afterward and pulled my radiator. There was so much mud covering hte fins I don't know how it ran cool at all! so maybe just try cleaning the radiator inside and MOST importantly the outside!

 

Last time I came close to overheating (thanks to a 2" BL and no radiator drop) the intake air temperature was showing 165F when news was saying 90F. Freeway, 2 rows of cars idling to the left, 2 rows to the right, summer sun, dark paint job, dark asphalt, sound barriers on bath sides. I doubt even an aligned radiator shroud would of helped if the jam was even 15-20 minutes longer.