Dealer can?t find problem. Our Jeep has 120k miles and it has the towing package with heavy duty cooling system. In Sept we were returning from a very mild summer in WA when we hit hot weather and mountains in south OR the jeep overheated and we had it towed to a gas station. They replaced the thermostat and checked the fan relay and topped off the coolant (with the wrong type). The Jeep continued overheating when stressed the rest of the way home, another 600 mi. We took it to the Chrysler/Jeep dealer and they flushed the system of the coolant mixture, replaced hoses, fan clutch and the thermostat ($900). The Jeep ran ok a short while before overheating again. Returned to the dealer and they did all their tests and everything OK. A while later again overheating and returned to dealer. Their tests again showed no problem, but the mechanic noticed the aux. fan did not come on when AC turned on. He ran his own tests and decided either the switch or the relay for the fan was faulty, with the switch more likely. They ordered a new switch ($60); the switch didn?t fit. Called the supplier and requested the correct switch and again the switch didn?t fit. The mechanic said he could file the prongs to make it fit and did so.
The jeep ran excellent for a few months. In Feb. had overheating again, this time the dealer found sludge from the old mix of correct/incorrect coolant and flushed system twice ($200). Jeep ran OK for a couple months then again overheating. This time it made it over the mountains fine but driving along flat I-5 south of Redding it overheated. We stopped and after the reservoir stopped boiling (10 min) the temp gauge was fine. We drove for 1-2 hrs. and heats up again. This keeps up till we get home, 400 mi. later. Dealer does his tests and everything fine. I tell them the aux. fan seems to be randomly shutting off on its own but it does not act up for them so there is no problem.
Anyone have ideas for identifying/fixing the problem? Could the replacement coolant temperature switch for the aux fan not be compatible with the 2002 Jeep?
I’m not going to try to read that b/c I’ll go blind.
Some people are nicer & more patient.
Or you could reply to this thread with the same info broken up into readable segments, like paragraphs.
This sounds like a problem that happened in stages. But the bottom line is that right now you should flush the whole system with the heat on using just water, and then replace the radiator and coolant. At the dealer. It seems likely that the two flushings by the dealer did enough in February to keep the car cool, but then the weather warmed up and you still had a partially effective radiator that could not keep up with cooling the Jeep whike climbing long hill.
In the future, in the event your car or truck’s temperature gauge is over two thirds of the way to the red line, or just has an idiot light telling you it is overheating, turn off the A/C and turn on the heat, with the fan at full blast. And don’t ever use the A/C while climbing mountains or even long steep hills.
I would do a hot pressure test on the radiator. Sometimes a head gasket will leak only when hot and the engine is straining (like when climbing a mountain). You put the pressure tester on a cold radiator and run the engine until it reaches normal temp. Then shut off the engine and with the tester raise the pressure and see if it holds pressure. If it doesn’t , listen and see if you can hear where the pressure is escaping,
PS - no matter how high the pressure builds don’t try to relieve the pressure. The Docs at the burn unit and I all agree on that.