Skip the auto shop - Our mechanics make house calls

Q: Car is overheating, usually when it's hot and the engine idles.

asked by on

I replaced catalytic converter, coolant tank, brakes so far. The car drinks coolant like crazy when it's hot outside, and then it overheats of course. There's brown sludge like stuff in the coolant tank. It doesn't burn oil, so I don't think it's a head gasket. It overheats only when it's hot and I'm idling. If I keep the car in neutral and rev the engine, it's fine for a while. My fans work; both of them come on normally. The heat works, so not thermostat issue.

My car has 182000 miles.
My car has an automatic transmission.

A: You most likely have a transmission cooler ...

You most likely have a transmission cooler that is leaking into the coolant inside the radiator. The transmission cooler is built inside the side tank of the radiator, and if it blew out, then you will have transmission fluid getting into the coolant and cause it to overheat. You will have to replace the radiator and flush out the cooling system to remove all the oil in the system.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: How do the Illuminated Entry lights work?

Your car is equipped with an Illuminated Entry system that turns on the lights to provide better visibility when getting into the vehicle. Here’s how it works: When you use the remote to unlock the doors, the interior lights...

Q: Car overheating

If your vehicle is overheating then the first thing to check is for any leaks in the system. If the water pump is leaking then have it replaced with the thermostat. If the engine is damaged from the overheating then...

Q: When do I need a transmission oil change?

The industry rule of thumb is to replace transmission fluid every 40,000 miles. Some vehicles call for it to be changed sooner, some later. The recommended service intervals should be listed in your vehicle's owners manual, available with a call...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...