Ferret

Hey all,

Friend of mine from ArsClan clued me in to this forum as the place to ask tech questions about my old truck. My girlfriend drives it now, and we've run into some persistent overheating that the 3 different mechanics we've taken it to are unable to diagnose or repair. I don't have any direct experience with it, so I asked her to write up what she's seen happen with it thus far.

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Ambient temperature High 70's to 80's - overheats after I've been driving for awhile with the air conditioning on and I slow down or stop (like at a traffic light or something). At this temperature, if I turn off the air conditioning, the truck usually manages to recover.

85+ (or so) - As long as I'm moving pretty fast (45+), and I'm not in stop-and-go traffic, I can run the air conditioning and be fine. However, when I slow down or stop, just turning the AC off won't fix the problem. Turning on the heat, however, seems to keep things under control (although it's really unpleasant in the summer).

The fan works.

The thermostat has been recently replaced.

There's no problem with the water pump.

I don't have a leak in the radiator - as a matter of fact, I haven't had to put more coolant in it since the beginning of -last- summer.

3 mechanics (one of which has been a family friend for more than 20 years) have told me they don't know what's wrong. The family friend said he thinks it may be air circulation and suggested that I have the radiator pulled out and pressure washed to dislodge bugs and other debris.

As of yet, I haven't had to pull over because turning the heat off gets the temperature down to a safe level.

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Anyone have any ideas, before I take this to the dealership and tell them to take it all apart until they find the issue?

mastacox

Fan clutch? They can go bad, and even though the fan may be spinning, it isn't pulling enough air to cool the engine...

gilby4runner

burb the system? Air trapped inside the cooling system after the thermostat change?

ChickenLover

I would assume the problem is with either the radiator or the fan. I would have the radiator professionally cleaned. If the problem persists, I'd replace the fan clutch.