ROG100

Myth or fact - has anyone any pictures or experiances where the metal impellar has milled a hole in the block????
From what I am seeing there is a limit to how far towards the engine the impellar can travel. It would have to be continually powered from the belt and pully to achieve such a result. Surely the pulley would come off and the belt fail before that happened.
Just looked at the pictures of the pulley coming forward of the shaft on John's car. Could this failure be more associated with the fit of the pulley to the shaft. It would be impossible for the seal cartridge to move forward.

PorKen

It looks as if Mike's impeller has been pressed on farther than Roger's new ones. Too far?

All the pumps look to have some variability in how far the pulleys/impellers have been pressed on.

PorKen

The gap is definately too large on the machining pumps from the cartridge movement. The proper gap looks to be <=1mm.

I wonder if some of the plastic impellers started spinning after they came in contact with the block.

I bet dropping the water pump on the pulley would weaken the cartridge seal/fit. Post manufacture, perhaps even in shipping.

ROG100

I have sat here and searched Rennlist for WP failures in every forum. Found very little and nothing conclusive. I read a lot of threads were people pointed to WP failures only to find other causes.
Found nothing on Laso WP's that would give reason to doubt there quality apart from the roughness of the casting.
There must be more war stories out there.
H mentioned laso failures and I trust him 100%. However where are they documented?
1) The impellar walks towards the engine and on contact goes no further.
2) The pulley comes of the shaft (JV's car).
3) A Laso pump poll was only positive with no negatives.

Please give me something to go on?

I'm calling "Urban Legend" until we prove otherwise - hopefully that will stimulate some responses 8>)

ew928

Year before the Texans invaded SITM (I think) there was a nice S that was being repaired at DR's place. Think there was coolant leak and removal of the WP revealed it had begun to munch on the block. Don't think there was any other problems, but my memory is fuzzy.
Didn't inquire what type of WP it was that failed.

ROG100

Ken,
Checking all my stock and also the one I stripped apart. The only datum for the correct fitting of the impellar and pully is to get it flush with the shaft. There is no shoulder on the shaft to position the pulley or impellar during the press process.
As long as the clearance for free rotation is maintined a few thou here and there is not a problem.
I am going to guess that the impellar is placed on the shaft and then the assembly placed into the casting. Then the pulley is put in place.
Tomorrow I will put the pump back together to check this out.
Roger

ROG100

Ernest,
Seen a few pictures of the steel impellar "kissing" the block and causing some scores but nothing further. In many cases this could be the combination of low tolerance of the cast impellar, and the position of it on the shaft at rebuild time.
Roger

PorKen

From Mike's unfortunate experience, I'd say if the pump is leaking, don't run the engine, until it is replaced! Especially if it is a newer pump. It's not leaking from the seal, but around a 'floating' cartridge!

Bill Ball

I'm pretty sure the impeller on an 86 Heinrich bought had migrated back. I helped Heinrich replace this. This WP had multiple failures. The bearing was shot, the shaft had migrated back and the impeller had moved back off the shaft some as well, but the seal did not leak. According to the PO, smoke came from the TB area as he drove the car. It's a damn nuisance when they do that!

Bill Ball

You might ask Jim B. 928 Intl will not accept Laso cores. Jim said his rebuilder won't take them, but then I received a rebuilt Laso "by mistake" from 928 Intl.

ew928

I tend to think of 'kissing' as something pleasant and pleasurable.
The scoring i've seen is more in the whips and chains and interesting claw marks on one's back category. Not my cup of tea.

Metal impeller spinning in close proximity to the block is good.
Machining materail from the block is probably not so good.

The metal impeller WP in my 928 had better behave.

ROG100

Bill,
I am 100% convinced that the Laso casting has no bearing on the issue at all. So there is no reason for a rebuilder to not accept them as cores.
What is important is the seal cartridge, and the impellar and pulley. That is all that is changed during the rebuild. That brings up another question - are the pulley and impellar changed or is it just the seal cartridge????
There is a lot I am still trying to understand and will try and talk to some of the engineers at Laso tomorrow.
Why Laso because they have an engineering team and supply water pumps for most Porsche cars as well as Audi, VW, Saab, Volvo and BMW. They are also interested in what I have to say which is more than can be said for the rebuilder/rebuilders.
86 failure - Maybe this was the the Laso failure that H mentioned. I am not saying that WP don't fail quite the contary, however these sometimes get discussed out of proportion.
At the moment and based on posts that I have read failures are at the rate of 5 per 1000 WP's.
I have sold over the last three years just under 300 rebuilt WP's with no failures. Taking into acount that I may have a failure with the WP I supplied to Dan but not yet conclusive.
In this day and age that is way to high a percentage.
I want to be able to sell a WP and not have it coming back and biting me in the buns and upsetting my customers.

ROG100

Ken,
Do you know what the spring is for on the seal cartridge?
*** refer to a spring back up on some of there seals. In cases where oil is the pumping medium.
Roger

byrdman454

Roger,
Do you need any more pics of my failed WP? I am probably going to send it back to 928 INTL this week. I do not really have a choice but to get whatever they send me under warranty. I hope I have better luck with the next one. My coolant is so saturated with metal it must be replaced. I guess I am still out some $$$ with this failure even though the WP is still under warranty.

ROG100

Mike,
It would be real useful to post or let me have close ups of the impellar where it fits onto the shaft and likewise for the pulley.
Also can you measure the gap between the impellar and the casting please.

928 Int is the most reputable company I have had the pleasure to deal with and they will treat you right. These failures happen and I know it is a PITA to go back in there but as a supplier they are dependant on there manufacturers/rebuilders. Apart from very rare situations like this there track record is 100%