Proactive replacement of water pump

I decided to replace the original water pump in my '02 C2 and install a low temp T-stat. I tested the T-stat on the stove with my Fluke temp monitor and a dial indicator, both which agreed. It barely starts to open at 160, and is maybe 30% open at 170, and not really full open until 190. However, I'm sure the amount of flow gained between 180 and up is minimal, but it works fine. I still have to test the old one, and see how it compares. I carefully inspected the od water pump, and at first glance, it appeared fine. The impeller blades are fully intact, no roughness or wear, and not brittle. The old pump itself turns far easier than the new one, and there is distinct bearing noise, not heard on the new one. If I apply pressure and rock the pulley, I can feel some play in the bearing, but there is no sign of leaking. I always though there should be no play at all, so maybe it's days were indeed numbered, so worth the effort to me. (Seriously, even though I only have 48k mile son it, it's an 11 year old water pump with a known issue with plastic impellers that can waste an engine, and the current revision of the pump is like 4 after mine.) All the cavities in the T-stat part of the block and the pump part, were spotless and clean, zero signs of any corrosion or film build up, and all the hose interiors looked great, so a healthy cooling system. Car is still apart (other issues), so I haven't yet tried my new Airlift vacuum tool to refill the cooling system. IMHO, this is a royal PITA maintenance set, and I've been at it for 2 days (along with the AOS) and had I known I'd have as much trouble removing the pump, which other seem to have had little trouble with, I might have paid to get it done. NAAA...what fun is that...

I just bought my water pump - targeting January to install. I don't know about little trouble - no one seems to say it is easy.

Agreed it's a bit of a pain in the ***. For me, I couldn't get the hose off of the the T-Stat without cutting it off, so I ended up having to take the T-stat off to get the water pump to drop down. I think that is the easier way, and just plan on replacing the T-stat at the same time (never a bad idea while you are in there) or for an extra 6 bucks, just plan on replacing the gasket as well. All told, I was probably at it for five or six hours. If I had to do it again, I could shorten that time by a few hours because I would just take off the T-stat housing right away, instead of wrestling with the hoses only to realize Stuttgart's version of Popeye installed mine, and they will have to be cut off to get them off. Cheers, DS

Just recently bought all the parts for this project and my local indy will do it all for $570 (WP, reservoir, T-stat, belt, bleed system). Read up about low vs OEM T-stat and had decided to go with the low...but indy adamantly insisted: HECK NO, OEM only (hope I do not open a can of worms with this ) P.S. Have also been reading all the DIY articles/watched the videos and INITIALLY thought I could DIY but got had a change of heart/mind after reading some threads how it can be a PITA. Best of luck to you.

Seriously, the decision is yours, and I don't want to start another T-stat debate either, but do a search on "Hartech" and "thermostat". It's a long article, but very thorough, and based on engineering and experience with these particular engines. You can move forward towards the end of it and read the section on cooling and design. I'm a mechanical engineer, and I had majored in Thermo-fluids, and there was NO DOUBT in my mind, and after looking at the design, that the 160F T-stat is the correct way to go. It is made by the exact same manufacturer as the OEM. The same temp T-stat is used in later Porsches with similar layout. It's do-able, but you need a good workshop and tools, IMHO, if you don't want to drive yourself insane. My biggest gripe working on this car, is that Porsche puts things in SO tight with such limited access, for no real reason, it seems. And they love to try to use as many different connectors, fasteners, bolts, etc as is possible. The K.I.S.S. principle was obviously never taught at Stuttgart.

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This is how all (95%? of) water pumps fail - leaking at the bearings. If there's any play or noise at all, the pump should be replaced - don't wait for it to actually leak. Personally, I've never seen the impellers fail (but I know it does happen).

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Most threads about it say it is time consuming and awkward, but not overly difficult. One guy said he did it in under 3 hours. Maybe the MKIIs just are more difficult. I see you have a MKII, too. Good luck, let us know how it goes for you. Maybe I'm just a wimp.

Just changed mine a few weeks ago, and had more trouble with the hoses than with the pump itself. Quick question for others: Does anyone collect the old pump cores for remanufacture? I've got the old pump in the garage, and was going to toss it, but would prefer to recycle it in some fashion.

My pump started leaking yesterday so I'm changing it today. Starting in about 30 minutes...

Mine started making noise at ~90k, so I had it replaced.

This will certainly be the only maintenance I will NOT do myself because of the weird vacuum refill thingy. I do not own a compressor and it seems quite complex. Too bad because I also wanted to add the third radiator while I was at it, but I am really freaked with the vacuum process. I hope someone can make a good DIY about the vacuum process. I think I have seen it somewhere where it involves that special vacuum tool and where you put your new coolant in a big bucket ready for the sucking vacuum to push it in... I hope you guys can talk about that part, as I think I can handle the rest. About low temp stat, I assume this would put me in trouble with my extended warranty in case something fails, right ?

The vacuum refill isnt too complicated and I've refilled my system twice using it...once when a hose let go and the second when I had to replace the lower hoses with the new current parts to get a proper fit. I must say, it isnt hard, but it is not easy either...

I had mine proactively replaced by an Indy. Watching the trouble he had....and he was experienced and had the car on a lift.....I was Pleased to pay him rather than try to do it myself. He also had specialized tools to get the air out of the system afterwards.

Actually I found it really easy with the vacuum fill system. Purchased it when I had to replace a radiator. Will do all my cars that way to ensure all air is out of the system.

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Makes me feel "better" about my decision to assume the role of plastic mechanic for this endeavor

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Still want to do it yourself, Brian?

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he already has a separate thread about this: old WP is already out and new one is inbound

I think that was Chuck, I am still on for doing it myself in Jan - I will let you know when!

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What I highlighted above was my thought as well. I don't remember the pump itself giving me any problems, but the hoses, UGH! Then again I did this when I had already dropped the engine to replace the AOS so maybe that is the part most people had difficulty with. But I thought the pump itself was pretty easy to get off, those hoses though were hell.

Once you own an Airlift kit (like $120, but you do need a decent compressor with a tank), you will use it anytime you bleed a system. It is real easy to use, far better than normal burp bleeding, as it pulls any air from the system to start, and the vacuum fills it. It also lets you know if you have a leak, before you fill the system. The only challenge is attaching the correct cone seal to the opening, like the expansion tank. Once that is done, it's easier to use than a Motive brake bleeder. It's all just easy to use valves and quick connectors. Well yeah, if you dropped the engine, of course it is easy to take off the water pump, or anything else on the outside of the engine. Most of us don't drop the engine for the AOS and water pump though.

Changed the water pump & thermostat today on my 04 C2 cabriolet (86K miles) today. Old Impeller looked fine and spun a little faster then the new, but looked in good shape. Some observations: 1) MAF connector - there are two types of connectors - on mine the release tab is on bottom - it was easier to disconnect by removing box partly and rotating upside down. 2) Belt tensioner pulley - mine was 24mm - some instructions indicate 15mm 3) Used a plastic storage bid to collect coolant - i had the back of the car on jack stands so it could fit underneath - worked out very well. 4) Thermostat removal tool would have been helpful - quicker. 5) Always seemed like I needed a socket between the standard and deep end, I actually end up using a small ratchet wrench i can put a socket on for most of the water pump and thermostat housing bolts. 6) Took me a good part of the day, started around 10:30am finished about 5:00pm - I could probably cut the time in half now that i have done it once. Time for a beer!

Congrats, you did better than I did! So you had no problems with that one water pump bolt in the corner, or getting it out and by the engine support brackets? Just curious, also, did you go 160F T-stat or new stock?

That bolt was the last one out and last one in on the water pump. It was also the one I learned to use the small ratchet wrench that i can put a socket on. It was very hard to start the bolt back on - once started - it turned out easy. below is a picture of the tool I am talking about. I went with the regular OEM Thermostat. I was able to loosen the engine support bracket enough to do everything - but was not that loose and seemed always in the way to make things harder. I had new metal gaskets for both and did not use any silicone or adhesive. I just cleaned all the surfaces well before I reassembled. It was a little tricky cutting the old metal gasket off (because it was original, it was connected by tabs to another gasket area).

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Congrats!

Congrats. Thus far it has been the most labor intensive job I've performed on my 996, but rewarding since my replacement was not proactive!

Brian, great job. To make things easier, get a factory hose clamp pliers and a hose pick for next time.

Yes, that looks to be a handy ratchet. The right combo is really critical to that friggin bolt. Yes, all the rest was exactly the same I ran in to, including the difficulty cutting the original metal gasket.

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How many gallons of coolant did it take to refill system after WP replacement? So I know how much to buy... thx

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with residual coolant in system, 2 gallons should be enough (mixed with distilled water) to replenish coolant lost from WP/EP/t-stat work (just had mine done by a local indy).

Thanks all, I think motor mounts may be next DIY (at my next oil change). Just need a 18mm deep socket. I concur with the above - 2 gallons of antifreeze should be more then enough, I ended up using less then 1.5 gallons.

Two gallons Porsche antifreeze and 2 gallons distilled water. I have about 1/2 gallon of mix left. But I also changed out the big hose conncted to the T-stat and the o rings on the oil cooler, & had removed my coolant tank to do the AOS, SO I lost more, I'm sure.