In the case of a water pump failure generally a big leak is a latter stage failure...

My '99Box suffered a sudden coolant leak yesterday while driving at approx. 60mph. I had the car flat bedded back home and I have searched for the source of the leak. It seems the water pump seal has failed. Is it normal for Boxster water pump seals to fail so dramatically? Their has been no gradual water loss or any squeal from the bearing.

I have just removed the water pump. What a struggle to get the socket on some of the bolts! The bearing and seal have gone BIG TIME, the impeller is broken and the vanes have been worn down.

Any tips on trying to flush any impeller debris out of the system?

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marty
I have just removed the water pump. What a struggle to get the socket on some of the bolts! The bearing and seal have gone BIG TIME, the impeller is broken and the vanes have been worn down.

Any tips on trying to flush any impeller debris out of the system?

to flow the reverse way through the cooling system.

Treat the engine and the radiators as separate systems.

That is separate the hoses so the engine is not connected to any radiator cooling hose. Then at the engine coolant outlet opening arrange to force water through the engine's cooling system passages and out the inlet opening.

In the past I've used a garden hose with a mix/match of smaller/larger pieces of plastic tubing (hardware store) to make some kind of half-assed adapter to get good enough water flow and pressure to the cooling system passages I want to flush. Wear old clothes. You can get wet.

Ideally you want to catch this water to be able afterwards make some attempt at tallying up what is in the water to see if it comes close to being the missing impeller material.

Do the same for the radiators. Force water into the radiators from the opposite direction of normal flow direction and this will remove/flush out any pieces of water pump impeller material. Again arrange to catch this water and verify you got what you wanted.

Be sure the coolant tank is clean too.

Do not fret too much if you don't see every piece, if you can't account for 100% of the impeller's lost material.

IIRC the normal coolant flow is away from the engine to the radiators so any debris if it remains in the system will get caught at the radiators which act as some kind of filter to keep debris large enough to cause blockages in the engine cooling system passages from any debris.

After the back flushing operation button everything up -- be sure to use a new t-stat, gasket and I like to test the t-stat on the stove in a pan of hot water and a thermometer to ensure the t-stat opens at its designated temperature and opens fully -- and refill the cooling system with a mix of Porsche anti-freeze and distilled water. Use a vacuum assisted refilling system to ensure a complete refill with no air pockets.

Sincerely,

MarcW.

Thanks for the valued advice Marc. Can you advise me the flow directions from the attached photo please from the coloured arrows?

I pray to be able to reverse flush the system by connecting my garden hose to one of the big hoses near the water pump? As I have the car on high ramps, I can't get under the front to remove the bumper to access the rads.


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Edited 2 time(s). Last edit at 09/24/2012 05:03AM by marty. (view changes)

Also - I can feel a bit of play in the two fixed jocky roller bearings. Should I replace these?

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marty
Thanks for the valued advice Marc. Can you advise me the flow directions from the attached photo please from the coloured arrows?

I pray to be able to reverse flush the system by connecting my garden hose to one of the big hoses near the water pump? As I have the car on high ramps, I can't get under the front to remove the bumper to access the rads.


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and from the picture I can't say for certain what the flow directions are. (Later: If I had to guess I'd say the water pump inlet is at the end of the long straight cast alum. section while the water pump outlet is the at the other large connection. While in the picture both connections appear to be at the same level, if one connection is lower than the other this is generally the inlet side as the water pump impeller wants to be submerged at all times.Sure with a full system it is but this is just some kind of cast in stone design philosphy to avoid the water pump impeller spinning at any time with the impeller not fully submerged to lessen the stresses on the impeller and keep the possibility of cavitation to a absolute minumum.)

However, in this case it is not as critical as it would appear at first appear. That is the force of the water from the hose is not going to be nearly that of the water pump and even if you do initially get it wrong the garden hose water will not drive any debris further into the engine's cooling passages.

You can pick an inlet and outlet at random and with the hose pressure turned down see what you get. If you do not get any debris from one direction reverse and see what you get. I think it will be clear from the results which is the reverse direction to that of the water pump's flow.

I would kind of like to have the car level but don't sweat it. The force of the garden hose water should force/flush the stuff out even though there is a bit of a slope that the water has to overcome.

Besides while you may cringe at this but even if some debris remains it will not in any way compromise the car's cooling system. There is enough over capacity -- I have read reports of these cars in competition event surviving just fine with one radiator damaged and the hoses pinched off to keep the coolant/'pressure from leaking out the damaged radiator with the other radiator able to provide enough cooling to keep the engine's temperature at normal -- that a bit of debris and a tiny reduction in flow will have no adverse affect whatsoever.

Last, I might be able to swing by a local Porsche dealer today and see if a tech can tell me the correct inlet/outlets and possibly even share some inside tricks to a flush of one of these cars.

Sincerely,

MarcW.

I fitted the new pump last week and so far so good... Had to add coolant as the system purged it's self though. Treated the car to a brake fluid change too!

Cheers for your help Marc. It's nice to know we are not alone when things go wrong!

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marty
My '99Box suffered a sudden coolant leak yesterday while driving at approx. 60mph. I had the car flat bedded back home and I have searched for the source of the leak. It seems the water pump seal has failed. Is it normal for Boxster water pump seals to fail so dramatically? Their has been no gradual water loss or any squeal from the bearing.

symptom.

The water pump was probably noisy though maybe not as distinct as one might hope for. Additionally the belt gets a sharp edge as it rubs due to an increase in bearing play.

But there are exceptions and you may have encountered one.

Maybe I was lucky (or luckier) in my car's case for I heard while a subdued low volume grumbling noise it was just distinct enough and troubling enough in a vague sort of way to prompt me to narrow down its source. I removed the belt and found some play at the water pump. The inner edge of the belt was sharp -- from rubbing -- while an older belt -- just recently replaced by me -- that had at least 60K miles on it didn't show any signs of sharpness so I knew something was up.

I didn't even try to drive the car to the dealer -- around 20 miles away -- but instead had the car flat bedded there for a water pump job.

Sincerely,

MarcW.