997 engine fan
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Discussion

Baggie Man

Original Poster:

4 posts

111 months

Friday 11th August 2017
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I have a 2008 911 997. Have just noticed that the engine bay fan seems to running continuously more or less from cold. The temp gauges are constant and do not indicate overheating. Any advice appreciated

STiG911

1,210 posts

195 months

Monday 14th August 2017
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Afternoon!

The Engine Bay Fan just vents hot air from the engine bay, it doesn't really contribute to actual engine cooling which is why the temp gauge looks fine (it almost always does, btw) So I'd start by checking the fan contacts, or the wiring to make sure none of it is damaged and possibly shorting.
If you've access to a fault code reader (or a kind Indy) you might find a more definitive root cause.

911tt

13 posts

116 months

Monday 14th August 2017
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I have a related problem on my 996 turbo.

The fan used to come on shortly after shutting down, and would do a good job removing the hot air.

Now, even after quite a brisk run, the fan never comes on after shutdown, and the engine cover grille gets really hot about 10-15 minutes after shutdown - to the extent where I daren't put the cover on the car for an hour or so.

No fault codes found by the Specialist!

Rockster

1,515 posts

188 months

Monday 14th August 2017
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911tt said:
I have a related problem on my 996 turbo.

The fan used to come on shortly after shutting down, and would do a good job removing the hot air.

Now, even after quite a brisk run, the fan never comes on after shutdown, and the engine cover grille gets really hot about 10-15 minutes after shutdown - to the extent where I daren't put the cover on the car for an hour or so.

No fault codes found by the Specialist!
Unless it is really cool where you are based on my experience with my 2003 996 Turbo the engine compartment fan should come on after a bit of time after the engine is shut down.

Also, this in spite of the fact my Turbo's engine compartment fan runs all the time the engine is on. There's a 2nd fuse that when installed controls this. Even so I have after having parked the car come back to it after a bit and had the engine compartment fan come on even with the car locked.

Haven't had to diagnose a bad engine compartment fan but the Porsche diagnostic computer should be able to command the fan to come on to at least confirm the fan works. It probably can retrieve any Porsche specific error codes. The fan is not part of the emission system so there will be no OBD2 error code available.

Thinking out loud: As a hack one would park the car then after having id'd where the fan temperature sensor use a heat gun (aka the missus's hair dryer) to heat the sensor and see if the fan comes on. Have to be careful one doesn't overdo the heating though. You don't want to fry the sensor.

Or if one is good with electrics disconnect the fan from the wiring harness and supply 12V power to the fan to at least confirm it runs.

anonymous-user

82 months

Monday 14th August 2017
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It's 'driven' by the temp sensor that is clipped to the drivers side plenum. Best way, as said is to use PIWIS or Durametric in 'output' mode and drive the output to check.

I have PIWIS if you're ever in the vicinity of SE London and want a check over.

G-996

163 posts

141 months

Thursday 17th August 2017
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@Baggie Man - try starting your car from cold with the air conditioning switched off, and see if the fans still come on.

I had the same issue in my 2003 996, and couldn't understand why I could hear the front fan coming on from a cold start. I did a bit of research and found the front fans also pull air over the a/c condensers in the front grills, so switching the a/c on also switches the fans on. I normally have the a/c on all the time, but when I experimented by starting the car from cold without the a/c on, the fans didn't come on. As a test after a minute or so I switched the a/c on, and lo and behold the fans came on.

Hope this helps!

Baggie Man

Original Poster:

4 posts

111 months

Sunday 20th August 2017
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Thanks but the problem is the fan in the engine bay fitted beneath the cover, hope to resolve it this week as I have a few days off,

Baggie Man

Original Poster:

4 posts

111 months

Sunday 10th September 2017
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Hi, me again. Car went to the indi dealer. He checked for fault codes and couldn't find any, said they couldn't find a problem, fan didn't come on after a hard drive etc. I drove 30 miles home, no fan on. Went outside to put it the garage an hour later and on it came. Following day drove it for an hour, modest speed, 18 degrees C, and on it came within 5/10 minutes, won't go off, pretty irritating. Any further guidance appreciated


The indi replaced the positive, starter / battery cable and cured the slow turnover issue for a very modest charge, £214.00, I think he's genuine and would solve the problem if he could, I guess I'll take it back again.

The sensor is all intact, connected and looks in good nick, I just don't get why they couldn't replicate the problem

AinsleyB

271 posts

109 months

Sunday 10th September 2017
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See if you can borrow someones fan, swop out yours and see. Then if the problem goes away its your fan. If not, its somewhere else.

Baggie Man

Original Poster:

4 posts

111 months

Sunday 10th September 2017
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Thanks, will try that if possible