jwillman

I just did a refresh of my clutch hydraulics with new master, slave, flex line and blue hose and the next day noticed I had a pretty good amount of coolant under the car and sitting on top of the oil sump lip under the front end.

I have had the car 6 years and never touched the water pump so I assumed it was time. The last two days I have driven it back and forth to work and not a drop - yes the system has coolant, level is constant in reservoir.

Is this a typical early stage failure mode for a water pump or do I have something else going on?

dr bob

No telling for sure without a little disassembly, but likelyhood is high.

Remember that there are large and small coolant hoses, plus the thermostat housing seal, that will dribble coolant towards the front area there. Coolant leaks usually leave a trail of crystals that helps identify a source, although G-05 coolant traces are harder to spot.

One of the best reasons for keeping the engine super clean is because it makes it so much easier to find and find the sources of fluid leaks. Recommendation: Clean everythig up real good. Then borrow a cooling system pressure tester from your local parts store. Put 5 or maybe 10 PSI on the system and see where the coolant comes out. Leaks may not show up with a little spray fountain. Time is on your side though -- leave it with that low pressure in there and your leak will find you.

mark kibort

i had a lasso pump i put on the race motor.
8 seasons and a little tiny leak after last season.
pulled the pump.. bearing feels fine, but makes noise when you spin it.. plus...the leak

thats 5000rpm average for 80 hours, so i imagine that like about 4x that if on a street car. call it 30k miles or so. anyway, if its leaking, its time.
problem is... what pump to buy.

GregBBRD

Simple.

Buy the cheapest one you can find, preferably with a metal impeller.

What could go wrong?

dr bob

Put a thick coating of orange RTV on both sides of a pair of factory gaskets. That should add a little clearance in case the impeller moves out on the shaft. The belt may not track perfectly on the drive pulley, but at least it's pushing back on the pulley.

What could go wrong?

skpyle

Oh hell...


Seth K. Pyle

GregBBRD

Make sure you run the cheapest pump you can find (with a metal impeller) continously at high rpms on your mega dollar engine in your race car when it is 105 degrees outside.

What could go wrong?

dr bob

Use High-Temp RTV.

jwillman

I type this next question in fear of the back lash but here I go anyway.

I totally get the don't use refurbished position but allot of these cars have to be running around with very old non-refurbished water pumps that have metal impellar's and I have not read recommendations that folks proactive replace those WP's for plastic impellar versions.

Is the basic design of the 928 water pump that poor? I would expect to read weekly accounts of another catastrophic failure of aging WP's or at least as frequently as cars catching on fire.

soontobered84

Jim,
Would you announce to the world that against all advice, you left an aging WP on your car, or didn't replace the rollers (Oh wait! That's Kiborts MO) or used a metal impeller that ground into the block and rendered the block unusable?
The more likely scenario is to put the car in your backyard and let it further decay until such time you determine that there might be a market for the car in which you believe it can be sold to make untold millions...

I did the TB on my GTS two years ago October. I determined that the water pump (a Porsche model, that had been replaced 4 year prior) was still good, functional, and had no issues. I drove the car to Third Coast in November that year and had no problems whatsoever. In December (that same year and 2 months after replacing the TB), I started the car for a jaunt, and it dumped every ounce of coolant on my garage floor. The water pump seal had let go. I will never do a TB job again without replacing the water pump. End of story.

mark kibort

Well, i get the concervative approach, but you know NO ONE has more race hours than i do, and lets do a little math here:

20 years of racing (plus the one on scots car) a few pumps have failed
thats over 200 racing hours
5 failed pumps:

1. PORSCHE plastic impeller got loose on shaft and gave intermittant failure. finally overheated in race an stopped spining.
2. brand new lasso, leaked upon installation on the original biuld of the holbert car
3. Brand new lasso put on the "race" motor .. lasted 8 full seasons, 80 hours of racing.... started a small leak after the last race of the season
replaced with Gebe pump ... see #4
4. gebe pump replaced after lasso finaly failed.. gebe we think has faild.. making bearing noise
5. scots pump (also lasso) failed and impeller moved into block. not much damage, replaced with new lasso, and is still fine after 4 years but not much racing now)

so, a reasonable man would assess that the water pump is a weak link and it doesnt matter who makes the pump.. they all can fail. ive never had more than bearing noise.

mark kibort

rollers???? are you talking about the idler roller? the thing that DOESNT really do anything? ive replace the tensioner roller when it was making noise or felt suspcious. mine is pretty new if i remember correctly. ill have to check the records.

oh, i also use the conti belt.. oh my.... stop the world...... its never had an issue. always at 5 on the tensioner and check both with the porsche tool, calibrated, and the kempf tool. I also developed a simple way to check tension to avoid catastrophic failure, without removing the covers. but what do i know... im not the one losing engines over tensioner, belt and other types of related failures!

soontobered84

Mark, I daily drive my 928s and I've never lost an engine either.

ROG100

Jim - I sell the Laso with plastic impeller for $275.

mark kibort

i fail to see the correlation.