hacker-pschorr

I love this place.

In many other car circles, plastic impellers are the tossed in the trash in favor of metal ones. The plastic units simply don't hold up as well as the metal ones. BUT......I'm not sure how many other engines out there are designed in such a way where the impeller has the ability to damage the block like a 928.

Many of these other cars have a "bird cage" style impeller, and they tend to break apart. I'm not aware of this happening with the 928 impeller, just the possibility it spins on the shaft. Moot point perhaps since both scenarios lead to engine temps rising.

The BMW and Volkswagen / Audi crowd are not big fans of plastic impellers. As you can see, this style impeller isn't going to "drill press" itself into the block if it comes lose or the bearing shifts forward.

Schocki

OEM Porsche pumps use a plastic impeller, I think there is a reason for it. Most of our pumps never see this kind of mileage from above in the pictures. I would never leave a pump for more than 10 years or 50000 km in my GTS (never did in any of my 951s either). No issues whatsoever since 1992, not going to change this in the future.

IMHO why are we even discussing this? We know from our experts, what to use. Just pick up the phone and get the part that fits and works as advertised, without giving you a headache in the future. No need to turn a good engine into a coffee table by saving a neglectable amount of money. Buying some cheap part and buying the right part after all is one thing, causing thousands of $ in damage is another. Why should it matter what others do in other forums with their cars from different manufacturers and what parts they use?

Wisconsin Joe

Why? In a large part because the 928 has, for a long time, been the 'discount Porsche.' (Captain Obvious, at your service)

Far cheaper to acquire than many other examples.

But not cheap to own.

For the 'average' person, the cost of the Porsche WP is ridiculous. Even the Laso, at maybe half(ish) is way more than they expect.

So they go on various sites and find a 'reasonably priced' one.

And, maybe find out the hard way why the 'good ones' cost so much.

Fortunately, this bunch of wingnuts, wierdos & miscreants is here to share information on how NOT to destroy your car (See the "I Love the 928 Community" thread).
And we will likely have new and ignorant folks coming on here asking 'why can't I use a $75 water pump?'

I'm cool with that. Ignorance is fixable. Stupid is a whole different issue.

Red Flash

I like this.

Wisconsin Joe

Thanks. Feel free to use it. Attribution appreciated, but not required.

It goes back a number of year to when I was a 'team leader' in a mill. I'd have to explain how stuff worked to the new people. Some of it was custom machinery, specific to the rather obscure product we made (spiral wound paper cans).
I'd go over everything, and then make sure they understood that I didn't mind explaining it again if needed.
I preferred to explain it as many times as needed rather than clean up the mess that could be made if they did stuff wrong (out of sequence shutdown on one machine routinely started a small fire).
Eventually I came up with that line.
Ignorance (not knowing something) is very different from stupidity (can't learn something).

ROG100

What is wrong with a Laso pump for circa $275/$295 - brand new, made in Germany with a plastic impeller developed for and with the help of the the 928 community??
I have sold over 2000 in the last 5 years with less than a 0.25% failure rate. Failure, when evident, was a leak through the weep hole and readily spotted by the owners. No catastrophic failures period.
Not something to be cheap about, especially when the consensus is to remove, check and replace and continue using at the belt change.
You can also buy a Porsche pump and apply the same use criteria. I sell about one a year so my stats for this pump are not relevant. Greg uses them so they must also be good if not more expensive.
Not an application for a cheap aftermarket made in China solution.

GregBBRD

I was a bit disappointed when Laso changed to the plastic impeller. By the time they got to "Version 3" of the metal impeller, I never saw one of those impellers move and considered that part of them to be virtually bullet proof.

The part that sucks is that they did not differentiate between any of the versions, externally. So, when we are doing timing belt work, we find ourselves needing to remove Laso pumps (if so equipped) and seeing what "version" it is.(Version #1 and Version #2 need to be removed and discarded.....immediately.) Rarely is there not some seepage or some other issue, so not many of these pumps get re-installed.

Yes, factory pumps are a little bit expensive (if you want to talk about expensive....you need to buy some 944 Turbo pieces....OMG!), but I know that I can install one and not have to even think about it, for the next 80,000 miles (We do not hesitate to put a new belt onto a factory water pump at 40,000 miles.)

Schocki

Very true! I owned both a 951 and a 944 S2. Nearly all parts for the turbo are double in price, it's ridiculous. FMPOV double the price is not reflected in double the fun driving. The 3.0 engine is a dream to drive every day. Lot's of torque at very low RPMs. On the track the turbo is quicker....

Strosek Ultra

Regarding the problem of the coolant pump impeller which in some cases may grind into the engine block, I received the following statement from the German Company GEBA about their 928 coolant pumps equipped with a metal impeller. You find the Google translation into English further down.
Åke

Wir wissen dass die Pumpen für den 928 sind und auch wir haben schon von diesen Problemen gehört.Wir hatten bei unseren Pumpen das Problem bisher noch nicht, da die Flügelräder mit einer hohen Kraft auf die Welle gepresst werden und nicht mehr Ihre Position verändern können. Zusätzlich bleiben wir mit unseren Abmessungen immer ca. 0,2-0,3 mm unter den Originalmaßen. Wir können uns vorstellen das dieses Problem durch eine ausgeschlagene Lagerwelle verursacht wird! Es gibt dann eine Bewegung sowohl in axialer als auch radialer Richtung was bei den geringen Spaltmaßen dann direkt zu einem Kontakt mit dem Motorblock führt. Aber das sind natürlich nur Vermutungen, da wir bisher noch keine Pumpe gesehen haben, wo das Flügelrad am Motorblock geschliffen hat.Für weitere Fragen stehen wir Ihnen jederzeit zur Verfügung.
Mit freundlichen Grüßen
Frank Herrmann

We know that the pumps are for the 928 and we too have heard of these problems. We have not had the problem with our pumps before, because the impellers are pressed onto the shaft with a high force and can no longer change their position.
In addition, our dimensions always remain approx. 0.2-0.3 mm below the original dimensions.
We can imagine that this problem is caused by a knocked out bearing shaft!
There is then a movement in both the axial and radial directions, which then leads directly to contact with the engine block given the small gap dimensions.
But of course these are only guesswork, as we have never seen a pump where the impeller has ground on the engine block.
We are always available to answer more questions.
Best regards
Frank Herrmann

Wisconsin Joe

Well, when the pump for a small block Chevy is less than $50, someone who is not well aquainted with these cars might balk at that price.
Especially when they didn't pay a whole lot for the car to begin with.

Fortunately, we have people like you who strive to provide PROPER parts, and even some less expensive alternatives (Laso pump & Volvo MMs are at the top of the list).

And this group to provide sound advice...

To those smart enough to listen.

worf928

@DrBob Can you combine these two water pump threads?