crunchy water pump failure - DIY or Shop?
 

Walked out to the car after work this eve and discovered a large puddle of coolant fanning out from under the engine block, dripping from the water pump... Refilled a couple quarts into the overflow tank, timed the drips, fired up the engine, listened to crunching noises emanate from the pump area and watched the drip rate accelerate, decided to flat bed it tomorrow and called the wife to collect me.

Given the crunching noises I guessing highly probable the impeller vanes are chunked.

I have all the parts at home for the replacement - was planning on it as preventive maintenance but at 56k/8yrs miles the water pump bit me first. :-/ No warning signs that I noticed, certainly no coolant seepage, though after replacement I'll listen carefully to benchmark against noises that might be clues the next time around that I missed this time.

SO:

Given possible vane fragments in play, DIY or have a shop (maybe even Barrier, the local dealer) do it?

Do shops have a flushing procedure for extracting fragments from the system?

Any thoughts appreciated.

I would doubt that many shops have a flushing procedure. I wonder though how much pressure the system is under, and if you can just use a garden hose yourself?

This may be of some help: http://www.pelicanparts.com/techarti...eplacement.htm

Best of luck!

search on here (or rennline) for DIY - i know USMC_DS1 has a good one somewhere on here. doesnt look too bad...altho i have yet to work up the confidence to do it by myself...

Depends on the size of the fragments should not be a problem if they are small. The narrowest point in the system would be the radiators and they can handle some debris. JMO though. I would tackle it myself if it happened to me. The worst that could happen is flat bed it over to you mechanic after you had it off and noticed it was a bigger job than you thought.

Sorry Dave, I misread your OP...it's more involved than just a swap. good luck and keep us posted.

I changed my water pump based on the guide by USMC. It was a straightforward process to do the change, but some of the bolts that need to be removed are really confined. I had to make numerous trips to the hardware store for yet another wobble extension to try to get a nut off. I also ended up yanking more parts off than USMC did...apparently because I didn't have the tight access tools he used. Edit: By extra parts I removed, I pulled most of the muffler system including the exhaust manifold, silencer and cats. Part of that was because I was also replacing the plugs/coils. However, it's so much easier to get to the bolts if you completely remove the motor mount bracket...hence the reason I pulled the cats.

Initially, I was going to suggest you yank the pump and see what you find. There is a slight problem with this if you decide to ship it over to the dealership. In order to get space to pull the pump, you have to loosen / remove the engine mount in order to get the pump off. That requires you jack the motor up and support it with the jack. So you'd have to rebolt the mount in order to move the car if you decided to ship it over to the dealer. It's not really a problem to do that, but sorta a shame to bolt all that stuff back together without putting on the pump.

I wonder if repeatedly filling the coolant reservoir wouldn't flush any impeller parts out if you had the water pump removed?

Best of luck.

--Von

There are two WP DIY's: https://rennlist.com/forums/997-foru...ech-index.html

I wonder if the crunchy noise might be related to worn bearings. Remove your s-belt and see if the WP pulley has any play. If the impeller bits did brake up then you'll want to inspect the WP to determine how much broke off. If just small bits then the system may just need a flush. If larger bits came off then you may want to remove and inspect the coolant lines running from the WP to the radiator and back to the engine. Ideally you'll want to catch any bits here before they lodge themselves in the engine block... in the worst cases these bits create hot spots which could result in a cracked engine block. To flush the radiators you'll have to remove the front fascia. Disconnect the coolant lines at the top and bottom and run a hose into it to flush out any bits that may have been caught in there. Since you'll already have the front fascia off... this would be an opportunity to add the 3rd radiator. GL and keep us posted.

That sucks, Dave. I'm considering a preventative replacement myself. Can you tell us how many miles you've got on it now?

Thanks

We've seen enough WP failures reported on our forum that it motivated me to replace it when my car reached 52K miles. In fact, it's enough of a concern that Excellence magazine did a write-up on it last year... I recall that they recommended 40-50K miles for replacement although many have been able to milk their WP for much longer. Every car has it's achilles and let's admit it... water cooling is a "more recent endeavor" for the 911 starting with the 996. So as a preventative measure it's another one of those relatively low cost items, ~$250 for the part, you can replace to hedge against much costlier expenses in DIY time and/or P-dealer $$$ down the road if removal of coolant lines is necessary to catch a lodged impeller bit or rolling the die with the engine when something is lodge within. Similar to how strokes negatively affect the body or brain. BTW, some members have reported WP failures as soon as 20K miles. If you get 50K miles out of a WP then IMHO you're likely at the end of it's MTBF - mean time between failure.

I fear the "crunchy" noise could be the impeller grinding its way into the case, in the worst of possible situations. Some impellers are metal, some are plastic.

Why BMW, Audi, and Porsche have insisted on using cheap plastic impeller wps is beyond me. My wp on the Q5 was replaced at 10k miles. Failed seal (recall item). Car has been bullet proof otherwise. Did 50k preventive replacements on my E39 and E46 BMWs. Won't wait much past 5 years when I have roughly 35k on my 997.2 before I swap wp as well.

It's a trade off in designed risk management. If the WP bearings fail and the impeller shaft axis is askew-ed out of alignment with the engine block then a polymer impeller would not grind out the aluminum engine block... whereas a metal impeller would potentially damage the engine block. I debated re the metal vs. polymer impeller design for my prior M3(from the factory it came with polymer) but there were aftermarket "performance" WP available with metal impellers available as well. Regardless I plan to swap my 997 WP as part of my scheduled maintenance vs. waiting until it fails.

Well said and I agree. Thus the answer is a wp replacement as preventative maintence vice waiting for failure.

I hear ya. I've looked at your DIY (which I am very happy that you created) and have been pondering it. My car has 46k on it now and I don't know if water pump was replaced yet (doubt it). I will add that to my list.

You can tell if it's original or it's been replaced by looking to see if the metal tabs of the 'multi-gasket', or whatever they call that double gasket design, are still intact. If you take a gander at a Victor Reinz gasket (that's the one I put on and the one sold by Pelican I think), you'll see it's actually two gaskets in one. There are 3 metal tabs separating the water pump gasket portion from the other part (looks like it's got a couple of rectangles on it). When Porsche built the motor, they used this multi-gasket and the tabs are still connected. To replace the water pump, you have to break those tabs off. Anyway, if you're standing at the back looking at the motor, those tabs are on the bottom right part of the water pump. You might be able to see them from the bottom of the car with a mirror. Otherwise, you'll have to take off the air filter housing, and maybe the serpentine belt to see down there.

--Von