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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHBlack plastic? in coolant expansion tank....
Leading reported evidence
Install low temp thermostat too, as you can see
Performed · outcome unconfirmed
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Read evidence and context
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Performed · outcome unconfirmed · Original poster
I also fitted a new low temp thermostat too, as you can see.
Leading evidence: 'Install low temp thermostat too, as you can see' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Inspect water pump asap' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion · Original poster
The engine has approx 100k miles on it, and although I have comprehensive service history including plenty of coolant changes and a new expansion tank a couple of years ago, I can see no record of the water pump being changed, so it makes sense to change the pump anyway.
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Suggestion
Remove the water pump and replace while flushing out the entire system with water.
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Suggestion · Original poster
I've drained the coolant - managed to get 22-24 litres out of the system using a gentle air line.
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Suggestion · Original poster
The engine has approx 100k miles on it, and although I have comprehensive service history including plenty of coolant changes and a new expansion tank a couple of years ago, I can see no record of the water pump being changed, so it makes sense to change the pump anyway.
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6 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261026T152433Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hello all,
I have a new-to-me 2002 C4S, which I've had for about 3 weeks. I've only covered a couple of hundred miles so far, but I noticed last night that there's a black non-metallic debris in the expansion tank.
They're hard and pretty small. The engine has approx 100k miles on it, and although I have comprehensive service history including plenty of coolant changes and a new expansion tank a couple of years ago, I can see no record of the water pump being changed, so it makes sense to change the pump anyway.
Anyone had the plastic impeller begin to break up and leave small bits in the coolant?
Cheers
Justin
If that's from the water pump impeller you could have a serious problem on your hands. I would inspect the water pump ASAP. If it's brand new, the previous owner probably hid the issue by replacing it and not being truthful. If it's old and parts of the impeller are missing you'll need to try to flush out any remaining pieces. There are a few posts on this subject here.
I would start by removing the serpentine belt and grabbing the water pump pulley, see if there is any movement up and down and in and out. Could be the bearing is getting loose at 100K miles and is allowing the impeller to rub against the engine casing. 100K out of a water pump is enough. Remove the water pump and replace while flushing out the entire system with water. Once buttoned up, add 50/50 mix of distilled water and Porsche coolant.
I'll agree with everyone here... that's the tell-tale sign your Pierburg water pump is on the way out. I wouldn't drive the car until all of the debris is flushed out of the system and a new water pump is installed.
Thanks all for your replies. I've started the strip down and will report back. Hoping the new parts arrive by the weekend and we'll be back on the road!
Justin.
Hello all. Just to update my earlier post. I've drained the coolant - managed to get 22-24 litres out of the system using a gentle air line. I've also flushed the cooling system through with raw water.
For the most part, the coolant looked pretty good - pink and clear (not cloudy). Running it through a sieve, however, revealed quite a bit of plastic debris, some of which was approx. 4-5 mm in size. The debris initially appeared black, but when rinsed well is actually a grey brown colour - just like the water pump impeller!
With the old pump off, you could see the impeller wasn't as defined as the new one. Whilst there weren't any big lumps missing, it didn't spin as freely and I think, judging from the condition of the drive belt, had been weeping slightly.
The new Pierburg pump was identical to the old one. It even has a Porsche part number cast into it, just like OE, but cost less than half the OPC wanted. I did use a new OEM metal gasket however - the one that came with the pump was fibre.
I also fitted a new low temp thermostat too, as you can see. Access was a bit tricky, but not too bad, even for a ham fisted oaf like me! Took me about three hours all in, so well worth doing for the <�200 worth of parts, especially if you're on the original pump like mine.
Thanks,
Justin.
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