Minor coolant leak. Any ideas??

[belfry]

My 2003 Cayenne V8 S has a minor coolant leak. I got a "check coolant level" warning and immediately thought that it must be my time for the plastic coolant pipe upgrade (117,000). I took the car to a North London Porsche independent who said that it was definitely the plastic coolant pipes and replaced them at a cost of £1,000.

One month later and I've still got a minor coolant leak. There is a small, but regular drip under the engine and I have to top up the coolant with about 2 pints of water every 1,000 miles. The water temp is rock steady at 90 degrees even in a London stop-start commute.

So, where shall I look next? Water pump leaking? Expansion reservoir?

I'm not really inclined to go back to the Indy who diagnosed the most expensive (and ultimately unsuccessful) repair so I thought that I might try a bit of DIY.

Any suggestions of what to check next gratefully received.

[1point7bar]

Are you confident enough to jack it up safely without damage to the sill?

[belfry]

1point7bar said:

Are you confident enough to jack it up safely without damage to the sill?

Yup. I can do that. Why?

[belfry]

anonymous said:

[redacted]

Ok. So I should have said that the water temp gauge never reads above 90 degrees even in stop-start traffic

[1point7bar]

anonymous said:

[redacted]

Can you explain this more?

IMO water temp sensors are analogue and there is no software involved between it and the gauge (also analogue).

Why would Porsche design a system that misreads deliberately?

[1point7bar]

belfry said:

Yup. I can do that. Why?

You can't see very much without removing the undertrays.

[belfry]

1point7bar said:

belfry said:

Yup. I can do that. Why?

You can't see very much without removing the undertrays.

Once the under trays are off, are there any specific areas that I should focus on?

[1point7bar]

anonymous said:

[redacted]

The thermostat keeps the water temp at a steady IIRC 88C.

I understand your point about dumbing down.

[D900SP]

Check the water pump, not an unknown failure point.

[1point7bar]

belfry said:

Once the under trays are off, are there any specific areas that I should focus on?

Maybe park it with the front undertray removed, somewhere dry and level.


Thanks Cmoose. Your point about the real temp is very valid.

Can your rad cooling fans reduce the temp and thus switch off?

I would ignore the level sensor and check the water level hot(carefully) and cold, manually, for a test period.

[Pope]

belfry said:

One month later and I've still got a minor coolant leak. There is a small, but regular drip under the engine and I have to top up the coolant with about 2 pints of water every 1,000 miles. The water temp is rock steady at 90 degrees even in a London stop-start commute.

Any suggestions of what to check next gratefully received.

Take it back - it's not fixed........

[1point7bar]

anonymous said:

[redacted]

I was suggesting a test.

[996ttalot]

Pope said:

belfry said:

One month later and I've still got a minor coolant leak. There is a small, but regular drip under the engine and I have to top up the coolant with about 2 pints of water every 1,000 miles. The water temp is rock steady at 90 degrees even in a London stop-start commute.

Any suggestions of what to check next gratefully received.

Take it back - it's not fixed........

+1 - it could still be one of the pipes replaced not fitting properly. It happens.