inactiveuser1228

The cooling fan on my 87 S-4 will not stop running after I shut down the engine until it drains the battery or I open the hood. Anyone with ideas on the cause or how to diagnose the problem?

Steve

bus stop

Had the same problem once with MY84 years ago.... short term had to unhook the battery to stop it. I took in in for service the next morning and it was diagnosed with a faulty relay. I didn't do the work myself so I'm assuming that was the issue.

Adam C

Shorted temperature sensor on the intake. Look at these wires carefully to make sure they are not touching / shorting out. Check the other temp sensor while you're at it. One on the intake and one on the coolant bridge.

shaaark89

try unplugging the air intake temp sensor wires (top rear of the intake) and see if it stops (obviously need to activate the hood switch to check)
very possible that the sensor has gone bad and will cause a runon condition. the sensor is designed to keep the fans on after the car is shut down if the intake temp is above a certain level.

Jim bailey - 928 International

The temp switch on the top of the intake manifold fails with that symptom. 928 606 217 00 about $30.

T_MaX

You may also want to check the temp switch in the radiator.

Location: Front, lower right side of radiator, if your standing in the front, facing at the car.

WallyP

"fan"? Does only one run? Or both?

First and easiest check is to unplug the temp sensor on top of the intake manifold. If that fixes it, the switch may be bad.

If that doesn't help, we'll have to get into the fan/flap controllers.

inactiveuser1228

Thanks everyone. You know what I'll be doing tonight.

Steve

Bill51sdr

Guess the car can wait, eh? Hey, are you racing tomorrow? If so, we can swap the sensor out of my car and into yours and see if that takes care of it, after the D.E. of course! Let me know or call me...

inactiveuser1228

Hey Bill,

I really want to, but my kids are flying back from South Carolina tomorrow and I'm not sure when they get in. I will drop by and say hi some time during the day though. Are you going to run? What about Andy? Kevin is headed to Vegas with a buddy to meet some woman he met in Maui. Hope he gets in trouble, if you know what I mean?

Steve

Bill51sdr

Steve,

Not running, Andy says he is though and I thought I'd show up and watch a while. Give me a call if you're going to drop by. The offer still stands on the sensor, I can drop by your place and try a few things. Give me a call or p.m.

fraggle

My '87 S4 had the exct same problem, it was the INTAKE sensor (thermo switch) which was easy to replace.

of course, I replaced the temp switch on the bottom right of the radiator, first.

goldknight

if shes a auto there is a temp sensor there that is tied into the intake temp sensor. Drove me nuts tracign that one on a 87 I was working on.