Overheating

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#11

02-14-2012 | 11:30 AM

Roader

Been Around A Long Time Member

Joined: Jul 2011

Posts: 1,008

From: Denver

Quote:

Originally Posted by bob6640

...Cooling fans come on as they are supposed to while driving...when I turn the car off, I hear the radiator always pissing in to the overflow tank, so eventually lose coolant. The fans turn off when I turn the ignition off, even when left in the accessory position. If I turn the ignition switch back to on position after turning engine off fans will run until engine cools...

I had the same problem, turned out to be a head gasket starting to go bad. What got me was the fans not coming on while the radiator was dumping into the overflow. From Jim Blake's "What are all the different "water-temperature sensors?" post in the DIY section:

Quote:

Fan switch A is located in the thermostat housing. It switches the fans (both) when the engine is running. Pretty sure that works when the key is turned ON but the engine doesn't actually need to be running.

Fan switch B is located in the nozzle for the upper radiator hose, near the head. This one has authority to switch one of the fans, after the engine has been turned off. There's a timer to prevent the fan from running forever even if the switch-B is stuck.

The only thing I can think is that there's not enough water to allow fan switch B to turn on; it sits up pretty high and, with much of the water dumped into the reservior, it's surrounded by air.

I was losing about a quart every 200 miles, with no other typical bad head gasket symptoms. If the sensors end up being good, you may want to try pressurizing each cylinder at TDC to see if water gets pushed out of the open radiator fill.

#12

02-27-2012 | 07:06 AM

bob6640

Thread Starter

Joined: Feb 2012

Posts: 5

Overheating

Thanks guys, Have been running with sensor B jumped and have had no problems at all. Flushed system and put proper 50/50 coolant mix and have not lost a drop since fans turn on after I shut off engine. Will invest in a sensor soon so I do not have to listen to the fan all the time.