I've actually seen very few bearings migrate....the metal impellers (on the original design Laso pumps) spin some and then start moving off the shafts.

I've actually never seen a Porsche water pump with one of the metal impellers do this (On virgin pumps....not rebuilt ones.) I always wondered if Porsche switched to plastic as a result of block damage or if they did it because the engines got more powerful and thus had the ability to change rpms more quickly....and they saw issues with the metal impellers in testing.

 

"Not rebuilt ones" is the key here I think. I've got a box of rebuilt pumps where it's pretty obvious that the metal or (quite-a-bit-thinner) plastic impeller has not moved axially on the shaft and that, thus, the assembly was migrating.

You are right, one would not expect a new casting with a new bearing to migrate... properly-engineered press-fit with no rebuilder Monkey's in there.

Can't say anything about the Laso. I've never installed or removed one with a metal impeller.


I'll take a page from Tuomo's book in the Baffle thread and put my bet on Accounting or perhaps the supplier's Accountants switching to plastic without any argument from Porsche. I've seen too many accountants screw up things to not assume that something that looks like an engineering decision is really an accounting decision. However, it would make me happy to think that Porsche actually spent that kind of engineering effort on it.

 

Engineers end up being accountants too. There's always the demand to make it better-faster-cheaper, evaluating the costs of failure vs the cost of success. The way-too-regular questions from the bean counters are around probability of failure, figuring we can easily justify not fixing something now if the failure probability curve is low for the next year. Beyond three years out, the money folks are blind to risk no matter how severe the impact. When something does fail, it's obviously a problem with the probability calculation. "You didn't say it could happen to US!"

 

While anything is possible, I doubt this is the case.

Porsche also made the impeller a separate part, presumably so anyone with a metal one could change to plastic.

 

There have been reports of Porsche water pumps failing, however there are so few sold that the % failure rate is potentially very high. I have documented 4 Laso failures in the last three years from the pumps that I have sold - Laso new with plastic impeller - out of the hundreds sold which makes the failure rate very slight.
My personal view is that all things mechanical can fail. Everything has an element of risk and the risk of a Porsche pump failing is much higher than a Laso. I use Laso on all my cars and sleep well at night. As of now I would not put a GEBA on one of my cars because they are unproven and the Laso (early with PKT) is readily available.
I have respect for Greg & Dave's opinion but they are very much in the minority when it comes to spending $1000+ on a water pump. I have sold three in three years that says it all to me.

Water Pump numbers from the wholesaler ---
Laso 928 106 015 22 (early 77 to 86) - total sales 2013, 2014 & 2015 YTD - 688 with 5 warranty returns. Failure rate .75%
Laso 928 106 015 20 (late 87 to 95) - total sales 2013, 2014 & 2015 YTD - 218 with 2 warranty returns. Failure rate .92%

 

Roger,
Add one to your list of non-rebuilt Porsche water pumps that failed. The GTS had a new Porsche water pump on it when I purchased it in 2009. I completed a timing belt job with PKn'er in October 2014, but I did not replace the water pump since it was only 5 years old, had no shaft movement and turned free and easy with no coolant leakage. The water pump seals failed right AFTER Third Coast 2014 in December. No catastrophic damage to the engine. I had started it in the garage, and it did dump a major amount of GS5 coolant onto the garage floor before I figured out where all the coolant was coming from.

 

Interesting.....

I've NEVER had a factory Porsche water pump, which I've installed, fail.....and I've installed literally hundreds of them.

Perhaps....

I have the correct factory tool to adjust the cam belt tension and we know that over tensioning causes water pump failures....

Or.....

I've only installed one Porkensioner and removed it because the actual tightness of the belt, when running, is a complete unknown even by the designer. (See above.) Plus it was impossible to set the cam timing, because the belt gets dramatically tighter when the engine is running....altering whatever you set the cam timing to, initially. Plus there is a complete lack of feedback from the belt light system....which is a fantastic part of the factory design.

Or....

I'm just lucky.

 

Since you bring up this ancient topic (PKTs being well proven now) it'd be super interesting to hear your measurements of the factory tension while running...failing that, at least the actual range of the heat sensitive Belleville stack while under 32V level tension? (Saying "Porsche must have known this" would be a cop-out here, BTW. )


Cam timing is always going to be dynamic with a timing belt (vs a chain), albeit less so with the 'Racing' belt, which does not stretch very much at all. Belt tension, sprocket to sprocket, is determined more by the pull of the cams by the crank at any given moment than some static tension measured on the slack (flapping) side of the system. You have seen what happens to cam timing using the factory system at high rpm as a regular belt stretches -using a timing light through the breather holes- where do you think all that stretched belt goes?


Later this summer I intend to go back for some dyno testing with some cam retard. My S4 came with the Racing belt installed, but my theory is that the regular 'stretchy' belt retards the cams at higher rpms. An accidental variable valve timing system, if you will.

 

Greg,
I have replaced far, far less timing belts than you, but I have been involved in replacing pretty close to 20 belts and this is the first time that I have NOT replaced the water pump when doing a timing belt job. I did not install this particular Porsche water pump, but it was installed just prior to my purchase of the car. I think my car was just pi$$ed off at me for not replacing the water pump like I have on every other 928 that I have worked on.

Maybe you are lucky. But I'll take lucky and good every time

 

I replaced a Porsche pump from a GTS a couple years ago, it was only a few months old. It did have a Porsche pump put back on though, customer supplied.

 

There's no doubt or question that parts are going to fail...especially in the hellish environment of a water pump, where the factory lubricated bearing is sitting millimeters away from steaming hot water, ready to steam clean the lubricant away. The seal between the bearing and the steaming water only has to "catch" a tiny chunk of debris and it is all over.

But to say that one brand is more prone to failure than the other brand is a real reach.

What's being said there?

"Porsche is ordering their water pumps with inferior bearings and seals to save a few dollars?"

Seriously?

I've personally dissected and analyzed every brand of water pump that anyone has ever made....except the GEBA. There's no one really "cutting corners" on the quality of the bearing insert or the seal (except the Chinese made one....that bearing is a real joke.) Even the rebuilt water pumps that Mark Anderson was selling had a really high quality bearing and seal.

There's no doubt that the Porsche casting is the highest quality of any other made, with the least potential for distortion from heat.....making bearing migration less likely.

As a business man....here's my reality:

I offer customers alternatives, when there are viable alternatives available.

I've installed a boat load of water pumps, over the years. I know that I probably am going to have to warranty some of those pumps...sh^t happens. However, I'm not stupid.

I will warranty the cost of the labor (and obviously get the part replaced) if the customer chooses the Porsche pump. Since I've had no failures, this is easy.

When we used rebuilt pumps (before they turned to crap), I'd also warranty the labor on those....because Mark Anderson or his rebuilder took care of the labor charges. Once multiple failures starter occurring, that quickly changed....and Mark quit selling rebuilt pumps.

However, I had so many Laso pumps go bad, I would tell people right up front that if the pump failed under the part warranty, I'd get the part replaced....but they were on their own for the labor. And if the impeller migrated and ruined the block, they were on their own.

Parts choices are almost always like buying a car.

If you buy a cheap car....don't expect it to be the same as an expensive car.

Here's another really common example....

I still find original radiator hoses that are over 30 years old on vehicles. Some I replace, some I don't....depends on condition. That's a damn good hose in my mind, way beyond anyone's expectations.

I stock both aftermarket and factory water hoses. I tell people right up front that I can sell them either one....with some additional information.

"The factory hose will last another 30 years, without any issues. They cost about $60.00 each."

"The aftermarket hose will have coolant seeping out of the cords (between the layers of the rubber, past the clamp) in less than a year, probably sooner.....guaranteed. Don't come back in a year and complain that there's a little "dried crust" of coolant right at the very end of the hose.....I'm telling you right now that it is a given. Also understand, right up front, there's not a snowball's chance in hell that it will ever last anywhere near 30 years. It costs $30.00."

"You choose."

The high percentage pick the factory hose, because they are "long term" owners. Some are "short term" owners that buy the cheaper hose.

Almost exactly like water pumps.....

 

Greg seriously - how many are you talking about - 5 - 10 or hundreds. Please share your stats with me as I have been keeping records for a long time now. How can the wholesalers be seeing so few failures, how can I see so few failures but you appear to be seeing lots and lots. I did not know you fitted so many Laso pumps when you are only fitting lots (hundreds) of Porsche pumps. Maybe you are talking about years ago when there were a lot of failures as opposed to current manufacture. Just trying to understand where you are coming from. I have never seen a plastic impeller ruin a block!!!. Sorry to be so glib but I need to understand these massive failures you are experiencing when the market in general is not. I do not know where you are buying your Laso pumps from but can you talk to your supplier and get the stats so we can compare apples for apples.
I will call SSF and IMC to get their stats next week.

The few Laso pumps I have had fail have been replaced under warranty and I understand that you also have to cover labor but I do not. I have no axe to grind here at all but this mass of failures has me very worried. I guess like fuel hoses I will need to stop selling alternative WP's to Porsche for fear of being sued.

Seriously what am I missing - I will also check failure rates with some of the other big 928 shops in the World.

David Chamberland - you only fit Porsche pumps can you add any stats to failures please - or do you never use anything but Porsche. Can you give an approx. qty of how many you fit in a year by any chance?

 

Rog, am I reading this right? You wouldn't put a GEBA on any of your cars, but you are selling them on a special. That doesn't sound like you. We've all come to implicitly trust you (deservedly), but you're selling a pump that you don't endorse?

After your 1st post, I was going to ask you to set one aside for me, but now I'm confused.

Bob

 

Bob,
I think you are reading my comments in a different way to my meaning. I sell lots & lots of 928 parts that I do not endorse because in many cases we have no choice.
87 to 95 water pumps are a good example - The new GEBA is our only choice in the "reasonably priced" range. I would not put one on one of my cars because I do not need to. My cars run the PKT and as such I can use the early Laso with the plastic impeller which is readily available.
All my competition sell the GEBA pump and time will tell if it meets or exceeds our expectations. About three years ago the same thing happened with the new improved Laso. I like many others had to take a chance with it until proven.
If my cars did not run the PKT and needed the 87 to 95 water pump I would fit a GEBA and watch it closely. I do not think the Porsche water pump is any better especially with its inflated price of over $1000.
Just my opinion. Others may and do differ.
I am asked all the time for "rebuilt" water pumps which I will not sell.
I also have to put food on the table and when I see the GEBA being sold for circa $700 when the real retail price is more in the $280 range - I see a special coming on.

In reality I have sold three from this thread - maybe that best answers the question.

 

Roger, Laso's decision to stop manufacturing the later-style pumps makes no sense particularly after their earlier willingness to work with you on revisions to the design (change to plastic impeller, then add a bushing). But given that decision, then it seems unlikely that they would continue manufacturing the early pump-- it's got to be the same tooling. And of course tooling for sand casting is cheap, which doubles the mystery. Either the shortage is temporary, or the supply of early pumps is limited also.

But certainly this is incorrect:That's nonsense. An aluminum die casting (i.e. the factory pump) is always better than a sand casting, otherwise why would anyone bother with expensive tooling? Die-casting allows alloys with higher strength and better hardness which are good qualities in this application, and of course the tooling is more precise. A sand-casting may be "good enough", but that does not make it as good as a die casting-- just cheap. And the metal impeller is a complete non-starter, for me.
So turning this statement around: For those of us who would not fit a PKT then our choice is a Geba or the factory pump, correct? That's a no-brainer. I don't consider these to be cheap cars, and if it takes $1134 to get a decent water pump then that's what it takes. But factory pumps don't need to cost $1134. Are you willing to match price with a Porsche dealer?