Porsche Enthusiasts Club Forum

Hi all,

My temperature gauge needle has taken to sitting steadily on the first white mark once the engine has warmed up (the one Clark's Garage shows as 80º), just occasionally venturing slightly above. It seems to take the same amount of time as always to reach the first mark. Previously, it would gradually rise up to the next mark in traffic (100º), at which point the fans would kick in and drop it back down to the first mark. The fans still appear to be operating/responding normally.

I've tested the gauge with a 500Ω potentiometer according to the procedure on the Clark's Garage site and, although the marks on my gauge don't correspond exactly with the resistances given, the needle moves smoothy as the resistance changes, from ≈287Ω at the bottom (40º) mark to ≈1Ω at the "oh bugger, that's the engine gone then" maximum mark.

On that basis, I've ordered a replacement temperature sender but it looks like a right bugger of a job, tucked in under the inlet manifold, with precious little leeway on the connectors into the bargain! Is there anything I need to bear in mind when changing it? Am I likely to lose a lot of coolant and need to bleed and top up the system after the job? Any other tips for replacing it, given the confined space under the manifold?

Thanks in advance,

Michael

Hello,

Removing the intake manifold is nowhere near the pig job its volume suggests it might be.
Once off you will have access to a lot of small things you may enjoy cleaning, idle control valve, checking breather hoses for leaks, check plastic vacuum hoses for condition, etc.

The inside of the intake itself is usually particularly dirty, a layer of dirt might have nested over the years at the bottom of the plenum.

With all that said the behaviour you described does not suggest that the sensor needs to be replaced, so I would not bother.

Hope this helps.

Thanks TTM,

Any idea what it could be then? It seems to me that it can only be the sender, since the gauge moves readily through its full range when the sender is taken out of the equation

Michael

Sorry, I had misread your description.

It the gauge does not reach the 100°C mark anymore but if it still does when plugged to an external potentiometer, then yes it's logical that the sender should be the culprit.

Thanks TTM

Michael