928Myles

Hi, 1990 S4.

Suddenly yesterday when I turned my car off the cooling fans continued to run. I popped the bonnet (hood) and they turned off - could not see anything obvious.

I know this has been discussed several times on here but cannot seem to strike that magic set of keywords in search to bring up a thread.

I tried disconnecting temp I & II with no change.

Car temp guage is where it normally sits and plenty of water so I do not think that any overheating is occuring.

Could someone please point me in the right direction of where to look (or an old thread about this)?

The fans eventually do not come back on when you close the bonnet switch but the have run for 30min with the bonnet closed without turning off.

I think that one of the sensors may be mis reading and not turning the fans off until the engine is fairly cool - what do you think.

I am due to go for a 2000km trip in it in a couple of days so would like a quick fix - otherwise I will just pop the bonnet when I stop.

Thanks,
Myles

Speedtoys

Pull the wires off the temp sender at the back of the top of the intake manifold.

928Myles

Yep - pulling the brown wire turns the fans off - thanks. Where to from here?

Myles

Speedtoys

Get a new sensor.


Thats just...IIRC, there to turn the fans on if the system things the intake is "too hot".


Go on your trip without it plugged in..enjoy.

WallyP

Either the engine is hotter than you think or the sensor is faulty.

The fans are designed to run after the ignition is switched off if the intake manifold is hot - it is normal operation. Thirty minutes is excessive, though...

928Myles

Thanks,
I have another sensor in an old manifold and (I think) a new one in my intake refresh kit. I will swap and see what happens. At least I know I can do the trip without an issue.

Myles

Speedtoys

Custom interior stalled
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Whats wrong with your interior project?

928Myles

Interior project awaiting inspiration, time & money.

Will get there one day.

Myles

Speedtoys

Ah..ya...there is that, and those.

928Myles

Swapping in the old sensor out of the spare intake seems to have solved the problem. Must put a replacement on my next purchase list.

The 'faulty' one read 15 ohms across the two pins when cool. The secondhand one read open line when cool.

Thanks again for the help.

Myles