16 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHFailed water pump?
Reported or suspected cause
air oil separator
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
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Discussions that report identifying a cause
1
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Reported cause
I did the coolant tank last weekend thinking that was source of my leak but it was the AOS.
Leading evidence: 'air oil separator' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'air oil separator' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check each rotating device' (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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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
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Suspected cause
The noise I heard was probably the edge of the belt giving way, not the bearings.
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Discussions that contain suggestions
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Suggestion
Get it home (flat bed, drive it), pull the rest of the belt and check each rotating device for play, noise, freedom of movement, etc.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
Chances are if you were hearing a bearing noise and the serpentine belt snapped it is a problem with the water pump but better to be sure than start replacing stuff you dont need
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Suggestion
Chances are if you were hearing a bearing noise and the serpentine belt snapped it is a problem with the water pump but better to be sure than start replacing stuff you dont need
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
16 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T033439Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
My car ('03 C4) started making a little noise today after an autocross event. It definitely sounded like a dragging bearing, pulley-type issue.
My wife drove the C4 and I followed. After several miles, I saw a piece of belt come out from under the car and had her immediately pull over. About half the width of the belt was gone, and I now had a coolant leak that I didn't have 15 minutes earlier.
Water pump, right? Any thing else it could even be?
(car is still parked in the same spot, by the way.... I have to go get it tomorrow.)
Like I told the guy who replaced his water pump without diagnosing it, get a pressure tester, pressure up your system and search for leaks, find out exactly where your leak is coming from and replace the part you actually need to. Chances are if you were hearing a bearing noise and the serpentine belt snapped it is a problem with the water pump but better to be sure than start replacing stuff you dont need
Belt half part(s) may have pulled a hose when it came loose. Get it home (flat bed, drive it), pull the rest of the belt and check each rotating device for play, noise, freedom of movement, etc. If one of the idlers, pumps, alternator are bad enough to cut/throw the belt you will feel/hear it.
I too had the same issue and it was the water pump. Despite what some have asserted, some water pumps can fail without any play in the shaft or any noise. Mine had none. The seal went and that was it.
BTW, keep in mind that the belts are directional once they are installed and can fail if they are removed and replaced in the wrong direction. Porsche explicitly says to mark the belt direction if it is too be removed and replaced.
Good info on the directionality of the belt.
Car is on the hoist. Water pump is definitely toast. The pulley had so much wobble that I guarantee that's what shredded the belt. New pump is on the way.
While it's up in the air, it's getting an oil change, a new magnetic drain plug, 6 new plugs and 6 new coil packs.
You heard bearing noise the belt ripped in half and the shredded parts flew out of the car and you couldn't feel any play/roughness in any pulleys? Wow!
No play, no roughness. Everything was in alignment. It may be that the belt gave way per the Porsche TSB regarding the belt and ate the seal on the pump. The noise I heard was probably the edge of the belt giving way, not the bearings.
Actually, if it's an '03 and has the original pump, there's a strong argument to just replace it anyway to minimize the chance of plastic impeller pieces from getting into the cooling channels and causing big damage.
It's not that expensive to do....and the amount you spend is a tiny fraction of what's involved if the pump goes south.
Treat it as a scheduled replacement wear item. No big deal.
I'm actually replacing mine this weekend as I have to change out the AOS and figured while I'm in there I might as well...
I'll start another thread when done outlining my experiences on how difficult it might be.
I did the coolant tank last weekend thinking that was source of my leak but it was the AOS. So I'll be repeating the steps again to remove it for this repair.
That's why I figured with nearly all the coolant out I might as well do the water pump too.
Can you give a link as to where Porsche state that if the belt is removed and replaced it has to go back on in the same direction or it will shred up or snap. I kind of find that hard to believe but worth noting anyway. Porsche may have meant the direction around the pulleys.
I believe the Bentley manual for my BMW states the same thing about taking the belts off and putting them back on so the are still running in the same direction.
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