[chuaed]

Hello guys,

 

Need some advice.  My temperature gauge seems to be fluctuating randomly.  On a few occasions following a cold start, the engine temperature needle sits below the 40 degree C mark  i.e. nothing happens and even after the car has been left idling for about 45 secs the needle does not move at all.   The needle then flips up to around 90 degree C mark all of a sudden and the reading then fluctuates between 90-115 degree C (the red mark) while driving. The temperature also often fluctuates up and down within a range of 10 degree C while the car is stationary.

 

It is typically 35-36 degree C weather here and given one of the cooling fans has stopped working (I'm waiting for a new replacement fan to come in), i expect temperature to be on the high side.  But even then, I'm not pushing the car at all and certainly don't expect the needle to hit the red mark?   

 

The radiator, temperature sensors, water pump, thermostat etc have all just been replaced.  The cooling system has been pressure tested and bled and all are in good order.   Hence I'm also inclined to think that i have a faulty gauge that needs to be replaced given that the needle/temperature reading seem to be moving quite randomly.  Especially when i have a 115 degree reading one moment and when I kill the engine and restart immediately, the reading drops back to between 90 and 100 degree C.  

 

Before I get a replacement gauge (which is rather costly), any idea what potentially could be the cause of the issue apart from a faulty gauge?  

 

Thanks!

Ed

 

 

 

 

 

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[Mark]

Check your grounds.

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[Waylander]

the sender for the temp gauge is further back down the block under the inlet manifold has two spade connectors on the top, try giving that a clean up.

 

Also the football shaped brass conductors on the back of the cluster can get a bit corroded (possibly not the right word) but make poor contact, take those off and clean the holes and the pins.

 

that might solve your issues.

 

the blue sender at the front is for the DME the one behind is for temp guage

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[94SilverCab]

I usually just tap on the cluster and it goes back to normal...

Jay

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[Bulti]

My fuel gauge did behave -to some extent- in the same manner. Cleaning all grounds on the back of the instrument cluster solved it.

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[SamSparks]

Had same symptoms. In my case it was the Water Temperature Sending Unit itself (part 928-606-201-01).

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[chuaed]

Thanks guys for the inputs.  

 

I have just replaced the water temp sender hence will rule that out for now.  Thinking i will have the fans replaced first and then re-check the grounds and temperature levels.  

 

And most unfortunately I now have another issue to deal with - the car could not be started this morning!  It cranks but the engine just wouldnt fire up.  I had the service guy come around and according to him the alternator wasn't fully charging the battery (battery was replaced about 6 months ago).  So we had the car jump started and I drove it around the block for about 15mins and then the tiptronic warning light came on.  The car stalled when i was slowing down at the lights and couldn't be fired up again.  Called the service guy down again, had the battery replaced since it was still under warranty and the car started up fine with tiptronic warning light gone.  However while I was reversing into the lot, the light came back on but the car did not stall this time around.  

 

I had the car sitting idle in the garage for about 3 months with the engine and gearbox stripped out for a major overhaul - the battery had been disconnected the whole time.  Finally had everything back up in the car last week and the car did stall twice the day the engine was back up.  But none since until today.  Hopefully all of these symptoms are isolated to a battery replacement needed.   

 

But otherwise what could potentially be the problem here?

 

 

Thanks

Ed

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[Waylander]

If the battery goes below 12.5v the tip light will come on so will the abs light



Sounds like you need your voltage regulator replaced in the alternator


Why would you need to replace the fans, if they go round they must be working if you have two they have two speeds, most of the time they only run slow.


They are rebuildable as new ones will cost you 700 euro from Porsche


As for your temp gauge I would clean up the connection first before rushing out and buying parts that I really think you don't need

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[ds968]

They are rebuildable as new ones will cost you 700 euro from Porsche

Yikes ! For 700 euro you can hire a couple of asian child-labor workers using palm leaves to fan your radiator for at least a year... What ?! Not PC ? :-) :-) .

My car's battery is always below 12.5 and I have never seen the tip light or the abs light triggered by low voltage . In fact , not sure the U.S. 968s have a tip light , do they ? And if it does exist in our cars, what circumstances typically set off that light ...other than low voltage, that is ?

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[chuaed]

Hey guys - Thank you all for your inputs.   So I spent a little bit more time observing the behavior of the car this morning.  And this was done with the engine fired up and gear engaged in Park.  

 

1. The ABS light flashed intermittently.  It was a weak flash and came up only once and went away almost immediately.  I have seen it flash about 3-4 times over the last 6 months while driving.  

 

2.  The Tiptronic light then came on permanently and when i shifted the gear into Drive, the car stalled immediately.  This sequence happened twice over a span of 10 mins.

 

3.  Voltage reading on the cluster ranged between 12-12.5V.

 

 

Do the above symptoms sound like a faulty DME relay or voltage regulator?

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[Waylander]

get an auto electrician to check your alternator output under load, sounds like a voltage issue to me

 

your voltmeter with the engine running should show between 13.8 and 14.5v

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[Mark]

I will repeat to check your grounds, not just the ones for the gauge but all of them and check the cables at the alternator and the battery

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[Bulti]

The fans are NLA over here. But it's nice to hear they can be rebuilt.

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[Waylander]

The fans are NLA over here. But it's nice to hear they can be rebuilt.

There are a couple on eBay uk for 20 euro

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[Bulti]

20?? Shoot. Where were you last summer?

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[Waylander]

Working on my car lol


I have a spare fan in my garage, one of mine is a bit noisy but not got around to sorting it out yet


I will do that later in the year when I put the new water pump on

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[chuaed]

Here's the latest update:  

 

Turns out the ATF level was low in the transmission and i've had to top it up with approx 2L of ATF.  Tiptronic light has not come back up since and hopefully stays this way!  Did also find that the alternator wasn't charging well which I guess is the cause of the ABS light flickering at times.  Have sent the alternator for servicing.  

 

Problem with the temperature gauge remains... grounds and connecting terminals behind the gauge have been cleaned but still did not fix the problem.  

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[Waylander]

It will be the hella sensor tucked right under the inlet manifold with the large and small spade connectors on

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[chuaed]

Just had another update from the workshop specialist -

 

Found that the wiring harness connecting the alternator to the starter was high in resistance and that was causing low voltage to be transmitted to the starter.  Measured 13.8V at the alternator and 12V at the starter.  I've been advised to replace the wiring harness and he reckons the one connecting the starter to the battery should also be replaced given its age.  The wiring harnesses don't come cheap!   Is there any possibility that this could also be the cause of the fluctuation of the temp gauge needle?  

 

All the connection terminals behind the cluster and near the inlet manifold have already been cleaned....

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[flash]

re: harness - contact higher connections (one of our sponsors).  they sell that harness

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