SharkSkin

This may be the first water pump out of 50,000 factory installs and all the replacements over the years that has seized with <500 miles on it(or maybe not, but bear with me).

This just proves what I said, and what Sterling expanded on so eloquently. It's impossible to manufacture any assembly that will have a failure rate of "0". I think that most of us would **** and moan about a new pump leaking right away... hell, I pissed and moaned about mine leaking from the seal at 26K. But that isn't such a big deal in the scheme of things... it happens, and you have plenty of warning to fix it before the bearing goes out, unless you never look under the hood.

What's really scary is that this one seized. Personally, I'm not really interested in leaky pumps. What I want to know is, how many pumps have been known to seize, from any source, at whatever mileage? Let's not count pumps that were run long after they started leaking, to the point where the bearing failed and they dug into the block.

I'm still very interested to know what happened here. Aside from the two failure modes that I already speculated on, another possibility is that the seal/bearing cartridge moved in the bore causing it to bind.

Black Sea RD

I have to agree with Sean R. on this whole water pump affair. The amount of failures experienced by the masses and what has been noted by Mark A. is very low and this thread really escalated.

From my vantage point there are currently only two real options available:

1. Buy a new Porsche pump

2. Buy a new Laso pump.

As others have noted and as we all well know, being mechanical devices there will be failures, no way around it.

What I find a bit surprising is how much concern this water pump issue generates given the amount of failures seen. There seems to be more instances of thrust bearing failure (TBF) of 928 engines than there are catastrophic failures of 928 engines caused by defective water pumps. However, people are willing to risk using inferior methods to counteract a known problem that could lead to TBF. A bit ironic really.

Yes, the last statement is a bit self serving, but true.

SeanR

I agree Constantine. 100%

928 at last

Just my thoughts....I have to agree with the Pros here. When you look at the incidence of catastrophic issues, the thrust bearing would be my first concern by a huge margin for A/T units. (Which I own). And frankly, I really don't think that Constantine's point was all that self-serving but rather accurate. (There are other methods and theories to prevent the TT shift, but having said that, his solution seems the utlimate with current technology), so all in, you really have to deal with the fact that there is no mechanical system that is truly failsafe (or if there is it certainly will not be cost effective with the level of redundancy which would be required to achieve anything approaching the ideal on any relatively complex system). Does a certain shuttle launch and or reentry come to mind? You do the best with what you've got, and considering the options available, a new water pump at the cost of roughly a quarter of the cost of one having the Porsche logo on it will do for me at this point. You have to consider the cost/benefit reality. We really have no significant data on the failure rate (for whatever reason) for the Porsche "New" units versus the quality new and reman units. So, it comes down to what's it worth to you? Personally, I can deal with the odds. Where I'd really freak though, is if I had indeed paid the freight for a Porshe "New" unit, and it took out the top end.

MTNKING

Hhahaha im with lizard on this one. But i'll wait for a beefy pump =0)

worf928

I agree and this point represents a set of details omitted from H's risk analysis.

If 1% of water pumps fail and provide evidence though leaking then in the statistical scheme of things it isn't a big deal. The probability of motor loss is very low provided that the leaking water pump is quickly replaced.

If 1% of water pumps fail due to bearing cartridge migration and the metal impeller machines the block then it is a bigger deal. But, not catastrophic.

But, if 1% of pumps fail and the mode is seizure, then it is a very big deal.

The probability of catastrophic loss depends upon the nature of the failure mode. A well-designed part (or system) fails in such a way that the most common modes have low risk of loss while the high-loss-risk modes are very, very uncommon.

So far, IIRC, this forum has seen one catastrophic failure of a rebuilt water pump on a high-power motor. If Doc Brown didn't have quick reflexes it would have been two. We have seen lots of leaking pumps, some under-rotating plastic impellers and some machined blocks. But, very few seizures.

SeanR

In general, we've seen very few failures. Should there be a better, or more updated solution for us? Hell yes, but the issue we run upon is who puts the tooling costs up. Who is going to put the neck out there for the solution.

I'd love to see what Sterling is talking about. Someone would need to get the design, the tooling, the 50k miles of testing to see if it works. That is the problem we run in to. Most of the stuff that is coming out for our cars from Carl, Mark A, DR, Roger is all development on their own dime. As of late I wonder what it would take for all of the BIG 4 to pool resources to get a solution.

There has been talk about an electric, or pulley driven. What would it take for everyone to actually get past ego's and come up with a solution?

I know that there are several that are working on it, testing it, and hope to get a better solution to market, the issues are cost vs return. Which leads us right back to what we are dealing with, which is a .5% failure rate. Which to me, is a damn good %, unless I'm one of those cars.

If everything on the cars is in top knotch condition, Cams gears, oil gear, tensioner, tensioner bolt/bushings (go Porken, those are gone) rollers etc and you can narrow the failure to the water pump, I'd believe that there is an issue with the pumps. Right now, with my limited experience, I've seen other components fail first.

GregBBRD

I accept leaky seals as just a part of life. Sure, I'm not too happy when I have to replace a pump that leaks, on my own dollar, but that happens.

I can't accept a new pump that seizes, without some sort of warning...like a loud bearing noise. I sincerely doubt that the bearing in these pumps, which appears to be of good quality, can just quit turning, suddenly. That would suggest that something must have "migrated" far enough to keep the pump from turning.

It will be next week, before we get this pump off the engine.....especially since the "new" pump needs to come from Germany. I'll be interested to see what happened.

worf928

Yup. I'm not as happy about leaky pumps as my post above might lead one to believe. I replaced two failed rebuilt pumps last year. One that resulted in some block munching. My observed failure rate is a lot higher than 1%.

I completely agree. I'm not at all happy with this failure mode. And while the data set of high-power motors is small, they are the motors that seem to bring about the seizure failure mode with rebuilts (and in your case Lasos.)

I have a PCNA plastic impeller rebuilt in my twin-screwed car. So, I'm all ears on water pump stories for the high-power motors.

I've made my opinion and preference known on the other water pump threads. But, in summary: I'd pay good money several times every year for a water pump wherein the seizure failure mode was a practical impossibility or was always followed by warning signs like leaking, etc.

Like the metal impeller...

blown 87

My failure with a new waterpump is a matter of fact and can be found with a search.

The thing that is different for Greg Brown and myself, and some others here is, even on a stock motor, we have to stand behind it, and it is never that part from Porsche, Lasso or where ever failed, it is I just paid him XXXX.XX dollars to fix my car and it only ran "This long".

We can do a 1000 right, and it only takes one guy to have a problem to give us fits.
l

Guys that fix cars for a living, (Greg Brown fixes cars also, they are just fixed to be faster) are the end guys, we pay (sometimes) the towing, the rental cars, and fix the damage the failed part did.

It is not our fault the part failed, we are the ones that spent the money for the 9201, and the factory oil seal tools.

But if the part fails, we eat it.

Bill Ball

Oh, I guess then I'd better order a couple right away. NOT!

Larry928GTS

Has anyone ever tried one of the Bosch or ACDelco 928 water pumps? Are they the same as the ones that are usually mentioned here on the list?

Bosch p/n 97127
ACDelco p/n 252-306

john gill

I wonder if these failures, as they appear to be increasing , could this be due to odd harmonics from the damper??

how many of these engines are using the stock balancer ???

And how many engines with failures are modified ??

Black Sea RD

I think you missed a few...

ROG100

Larry,
From my investigation Bosch and AC Delco do not make pumps for the 928.
I have seen them listed but found they did not exist when ordered.
If they do exist they will be a Laso, MPG (porsche OEM) or Hamburg Technic pump renamed.
I know they would not be Laso as there pump is not sold under any other name.
If it is HT that would be scary.
Roger