Leak possible water pump failure - comments would be appreciated

[Tamer]

Hi,
As usual, I left my daily-997 parked on level ground overnight and yesterday morning when I returned to it, I noticed a wet patch on the ground beneath the rear end - as shown in the photograph.

It hadn't rained that night, and the wet patch was directly beneath my car. I looked underneath and could see a drip from what I think is the water pump (see attached picture 2)...

Note that I had not even unlocked the doors to my car when I noticed this, let alone starting the engine (for circulation / pressure build up in the plumbing). The car had been parked there for at least 12 hours.
I got on my knees and looked beneath the car where I could see a drip, water droplet was forming every 30 seconds and dripping down. Suggesting a considerable 'rate' of leak... But... Looking at the (small) size of the wet patch on the ground and the fact that it was still 'leaking', I was confused about what was happening. At that rate, it seemed like the leak might have begun 1/2 hour before I got to the car (BUT HOW??? What could trigger such a leak when the car is parked up) The size of the patch suggests it hadn't been leaking all night.. I would say there was only about half a pint of water on the ground.

Anyway. I was in a major rush and with only 3 miles to go, I drove it to my destination, monitoring temperature levels on the dash very closely. Everything looked normal throughout the journey. I couldn't tell if there was a trail of water droplets behind me but the weather remained dry and after about 3 hours of being left in the car park, when I returned to the car I looked underneath again, I was expecting to see another wet patch but there wasn't any sign of a water leak on the ground, not even a few drops.. It stopped leaking...

I guess this is a sign that I should get a new water pump soon but I would like to understand if there is a logical explanation to what I'm seeing and more importantly, is the water pump likely to fall apart very soon, given these odd symptoms..

I would appreciate any advice or opinions and thanks in advance for reading my post.
Tam.
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NOTE:
I have tried without success adding my pictures to this post.

The images do not appear here because PorscheClubGB web site forces it's own site address into the image URL it asks me to enter,
as shown in bold here -> "https://www.porscheclubgb.com/forum/mywebsite.net/images/leak1.jpg" as a result of this 'feature' the correct address I type is ruined with the automatic prefix added to it by this PCGB web site. I'm sorry but I have no control over this )

 

[STiG911]

Okay - given that you didn't see any leakage after a drive and a 3 hour park, I wouldn't panic too much yet. (3-minute drive though, ouch - hope that's not a journey you repeat too often!)
It sounds like the pumps bearing seal or gasket is breaking down. Not enough to cause a full-on leak, but enough that it drips when the engine is fully cooled - which takes a long time.
Once the engine is running, heat will cause expansion thereby sealing the leak. Over time this will be less effective as repeated heating / cooling makes the situation worsen.
Keep an eye on the expansion tank and top up with coolant, using only the Porsche approved type (when the engine is STONE cold, to prevent air bubbles or a burnt owner!)
I wouldn't say the pump is about to fall apart but prevention is better than cure, so get it seen too soon-as.

Edit - Actually if it was the bearing I'd expect you to hear a squeaky whine, and as you've not mentioned it, I'd say it's the gasket.

 

[angusc]

Be careful, my water pump pulley shared off at 74k miles when I wss driving down to Portugal. No warning signs or sounds just a bang, charging light came on then an overheat before pulling over.

 

[Tamer]

Thanks for your reassuring comments STiG911.
Ps. It meant 3 miles or about 20 minute drive across town..

Your temperature theory makes a lot of sense and explains the seemingly randomness of the drip/leak...
Note that I haven't noticed any leaks since then.

As per your good advice, I will keep it topped up (with recommended coolant) and keep an eye on it. And seriously consider a new water pump & gasket replacement in the near future.

Has anyone replaced a water pump on a 997 recently? And, is a low(er) temperature thermostat (to that originally fitted) really a good thing, while I'm replacing the pump? Given that my car is not on track very often, may be once or twice a year.

Thanks again.
I appreciate the feedback.

 

[Tamer]

Thanks Angusc,
Sorry to hear about your unfortunate experience with your water pump.
I'm a little concerned exactly for that reason, as I'm planning on driving Bristol to London on Tuesday (about 120 miles).
I may take a hire car out for that journey and get this fixed ASAP to avoid a disaster.

Thank you for sharing.

 

[Tamer]

I have been to Porsche Centre in Bristol to ask about a new water pump.

It is £872 for a replacement. This includes the pump, about 4 hours of labour and 12 or so litres of coolant. They will "need the car for 2 days"... To test the water pump.
This will include tests to heat, cool down and check for leaks in between temperatures, so I don't think the quote is unreasonable, given the work involved.

With no further apparent leaks and a hefty price tag, I'm not rushing to get it replaced just yet but, I know it is on the cards and will need to be done in the near future.

For now, I have topped up the coolant with original/recommended type of coolant that I bought from my OPC on Monday. Since then I have done the London trip.
The coolant level is still between min-max. There are no signs of any form of overheating issues....I think I'll just keep monitoring it but I'm confident that it is not as urgent as I initially thought.