Capt. Obvious

I just replaced my water pump last weekend with a Pierburg pump (an OEM supplier) from Pelican parts (my original pump finally threw in the towel after 94k miles). The composite impellers are fine. Sure, they can break apart, but it's not really that likely. I feel like composite impellers are the next IMS bearing...

I also added in a low-temp thermostat while I was at it. The job is super easy (though a couple of the bolts are a bit of a pain to get at).

Ubermensch

That's not actually true. The OEM pump I purchased from Sunsent Porsche came with a metal impeller.

Barry Lenoble

Hello,

How hard is replacing a bad waterpump on a 2000? I'm very familiar with working on 944 models, but not the 996. Say that an oil change is the easiest and a 944 clutch replacement is the hardest, with a 944 timing and balance belt change in the middle. Is a 996 water pump change easier than the belt job?

Thanks,
Barry

Barry Lenoble
lenoble@optonline.net
89 944 turbo
00 911 Cabriolet

Capt. Obvious

If your example above is a 1-10 scale, I'd give a waterpump replacement a 2.5.

It's pretty straightforward (there is a great write up on how to do it on the Pelican Parts website). The hardest part is getting to a couple of the bolts, they're just in a very awkward spot to reach and you may have to get creative with your tools.

piiqmark

Flush it then flush it again and maybe if you are **** like my guy is flush it a turd time for good measure!!! Then burp and burp more - mine burped 3-4 times so be sure to have some pentofrost and distilled water at hand for the first 50-100 miles (well mine took 100 because i drove it home about 80 miles just cruising on the highway)

Youll know you burped when the temp jumps and the red light flashes

I probably added at least 1/2 to 3/4 of a gallon after the initial burp.

Capt. Obvious

Ha! I'm learning this today. First time I've gotten to drive the car since I changed the pump and did the initial fill/burp. I topped it off this morning before leaving for work and the level dropped quite a bit by the time I got there.

piiqmark

There is a little valve on the cap - drive with that open as well. Let's the air out. I left mine open a little longer than the last burp. It was middle of winter and never more than 30 degrees so it wasn't a big deal like it would be this time of year.

thirteeneast

Impellers have been known to fly off and give the inside of your cooling system a little gift.
Temperature gauge wont help you much I'm afraid.
Gauge = a means of estimating or judging; criterion; test. ( a guess! )

LordVicious

Plastic impeller is the correct answer. Carry on.

Hurdigurdiman

But when the impeller flies off... Doesn't the flow of water stop. Then the impeller stays where it came off. Then the temps go up because of no water flow. Then you switch off. A differant case if only a blade should fly off. Then we are in trouble. Mine I think is the original water pump. If thats metal or plastic I don't know or even care. If it starts to leak then it gets changed to a plastic bladed one in case the impellor breaks on that one.

jasper

The failure mode is that the bearing gets loose, the impeller starts to rub, and bits of the blades break off.

The blade shrapnel then travels through the water jackets and get lodged in the narrowest ones - often times the head.

Hot spots develop, which leads to cracks, which is likely to manifest as intermix..

Most impellers are plastic, the 997 "update" is metal. The plastic impellers break more easily when the bearing gets loose, but the metal impellers grind the engine case. Neither scenario is any good.

Either way it is recommended to check for leaks or listen for noises indicating a worn bearing, but better still....replace the pump before either occurs.

And you won't see this on your temp gauge Hurtin'Gurti man...once again if you had a shred of mechanical sense you might have thought twice about dispensing your own particular brand of wisdom....but go ahead and defer all the maintenance you want. We'll be there with all sorts of advice for you when something breaks

DreamCarrera

Relax Dude. I highly doubt anyone here is taking Hurdi's mechanical advice as GOSPEL.

I understand that Hurdi hurt your feelings in the past, but please try to get over it and move on. Your repeated attacks on him smack as a scorned woman.

jasper

Thanks for the reality check DC. I can let it go. I've been away a while and thought I'd check in, and knee jerked I guess.

Just reading up on some other threads and I can see HGM has been cementing his rep pretty good all by himself. I'll let him do the work from now on.

DreamCarrera

Flat6 Innovations

And you better hope that you never lose a water pump drive bearing.. When you do that metal impeller will destroy the crankcase by chewing into the aluminum housing. When this happens the system will never build enough cooling system pressure to avoid overheating.

Keep the plastic impeller and change the pump every 3 years despite mileage.

The Excellence article is great this month, their contributor on this article really knows his stuff :-)