WTF...Water Pumps!
05-29-2009, 02:20 AM
#31
928 Collector
Rennlist Member
Rennlist Member
a) there is no other vehicle on the road today that has as thin a water pump as the Porsche 928. This causes the impeller shaft to be held in place by the smallest bearing available on any water pump on any vehicle ever made.
b) the Porsche 928 water pump carries the timing belt and if it fails, all 32 valves will bend and the engine is toast.
c) There is NO RELIABLE ALTERNATIVE and their water pump WILL FAIL. They may get lucky and not lose valves.
d) They have to take their chances with the pumps out there today, until an alternative such as electrical comes along
05-29-2009, 02:24 AM
#32
Rennlist
Basic Site Sponsor
Basic Site Sponsor
Thread Starter
Hi Greg, i would warn you that a NEW factory pump may have been sitting on the shelf for a while B4 you get it.
When i rebuilt my 88 S4 engine i also used a Brand New Porsche pump, it started leaking after 1500 miles, i went with a rebuilt pump from Motorsport Slc .
They have a small number that get rebuilt and then put on the shelf so my rebuilt was days old, and has been fine ever since, plus while i worked there , i never had to replace any of the pump that i installed except my own as they use the rebuilts almost exclusively.
Might be worth a shot, Good Luck. on your motor, Stan
When i rebuilt my 88 S4 engine i also used a Brand New Porsche pump, it started leaking after 1500 miles, i went with a rebuilt pump from Motorsport Slc .
They have a small number that get rebuilt and then put on the shelf so my rebuilt was days old, and has been fine ever since, plus while i worked there , i never had to replace any of the pump that i installed except my own as they use the rebuilts almost exclusively.
Might be worth a shot, Good Luck. on your motor, Stan
Not convinced that the bearing and seal, in a water pump, have a "shelf" life. The seal appears to be a ceramic disc affair, not a standard rubber seal, that ozone could attack. The bearing is....well...steel. I'd think that your Porsche pump would have failed after 1500 miles, if you put it on the same day it was made.
An I'll take a whole bunch of pumps that leak...over one that seizes. Leaks don't trash an engine, if you don't get it shut off quick enough.
__________________
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
05-29-2009, 02:33 AM
#33
Rennlist
Basic Site Sponsor
Basic Site Sponsor
Thread Starter
Well I guess we just stop selling water pumps !!!!!!!!!!!!!
I stopped selling rebuilt WP's unless the customer insists after knowing all the facts.
I now stop selling Laso WP's because they fail on a very suspect (not stock) HP engine pushing everything to the limit.
I now only sell Porsche WP at circa $600 and they fail as well.
Sorry guys we cant sell any WP's anymore.
Just trying to say we need some sense of realism here unless you want to keep your rebuilt, remanufactured, Laso new, Porsche rebuilt, Porsche new on their forever. I promise you it will never fail - not.
Electric - well how long can you wait to get your car back on the road????????? What do we do while we are waiting for the development?
Sorry but I see no where to go unless we at least use something.
I stopped selling rebuilt WP's unless the customer insists after knowing all the facts.
I now stop selling Laso WP's because they fail on a very suspect (not stock) HP engine pushing everything to the limit.
I now only sell Porsche WP at circa $600 and they fail as well.
Sorry guys we cant sell any WP's anymore.
Just trying to say we need some sense of realism here unless you want to keep your rebuilt, remanufactured, Laso new, Porsche rebuilt, Porsche new on their forever. I promise you it will never fail - not.
Electric - well how long can you wait to get your car back on the road????????? What do we do while we are waiting for the development?
Sorry but I see no where to go unless we at least use something.
Perhaps there is a special "hell" that a stroker puts a water pump through....I just don't see it.
05-29-2009, 02:48 AM
#34
Rennlist
Basic Site Sponsor
Basic Site Sponsor
Thread Starter
05-29-2009, 03:04 AM
#35
Rennlist
Basic Site Sponsor
Basic Site Sponsor
Thread Starter
So, here's an update. The water pump started turning normally, once the engine cooled down. Perhaps I should just pretend that this never happened and just reuse the pump? Not!
We had been running it, but not super hard....never above 6,500. Oil temp and water temp low/normal. Big fans blow lots of air, on the dyno. Trying to do a bit of airflow research. The engine had been turned off for about 10 minutes, while we changed the air flow meter. The noise occurred on restart....but only above 2500 rpms...I think the belt just slipped without making noise, below this.
This might suggest that the water pump could have heat soaked and perhaps allowed the bearing to migrate in the housing? There is one thing that you can be sure of....I'll find out.
We had been running it, but not super hard....never above 6,500. Oil temp and water temp low/normal. Big fans blow lots of air, on the dyno. Trying to do a bit of airflow research. The engine had been turned off for about 10 minutes, while we changed the air flow meter. The noise occurred on restart....but only above 2500 rpms...I think the belt just slipped without making noise, below this.
This might suggest that the water pump could have heat soaked and perhaps allowed the bearing to migrate in the housing? There is one thing that you can be sure of....I'll find out.
05-29-2009, 03:34 AM
#36
Nordschleife Master
LOL thats sure good, a lesser guy would be.... "hmmm wonder whats making that noise, lets rev it up to see if it gets louder? SNAP...... OH ****! "
05-29-2009, 04:38 AM
#37
Rennlist Member
05-29-2009, 05:05 AM
#38
Well I guess we just stop selling water pumps !!!!!!!!!!!!!
I stopped selling rebuilt WP's unless the customer insists after knowing all the facts.
I now stop selling Laso WP's because they fail on a very suspect (not stock) HP engine pushing everything to the limit.
I now only sell Porsche WP at circa $600 and they fail as well.
Sorry guys we cant sell any WP's anymore.
Just trying to say we need some sense of realism here unless you want to keep your rebuilt, remanufactured, Laso new, Porsche rebuilt, Porsche new on their forever. I promise you it will never fail - not.
Electric - well how long can you wait to get your car back on the road????????? What do we do while we are waiting for the development?
Sorry but I see no where to go unless we at least use something.
I stopped selling rebuilt WP's unless the customer insists after knowing all the facts.
I now stop selling Laso WP's because they fail on a very suspect (not stock) HP engine pushing everything to the limit.
I now only sell Porsche WP at circa $600 and they fail as well.
Sorry guys we cant sell any WP's anymore.
Just trying to say we need some sense of realism here unless you want to keep your rebuilt, remanufactured, Laso new, Porsche rebuilt, Porsche new on their forever. I promise you it will never fail - not.
Electric - well how long can you wait to get your car back on the road????????? What do we do while we are waiting for the development?
Sorry but I see no where to go unless we at least use something.
The more power the engine makes, the faster it and the water pump are accelerated through the RPM range at full throttle. Accelerating cams that have more lift, and stiffer valve springs, at a faster than stock rate, is harder to do, and puts more strain on the timing belt. It also puts more sideways force on the water pump pulley.
05-29-2009, 09:18 AM
#39
Just a data point, I had a rebuilt pump fail on my car after about 8k miles - stock US 4.7, damn near the weakest engine. It didn't leak but the bearing starting making some serious noises. FWIW I have installed one of the new non-Porsche pumps that Roger used to sell, only a couple hundred miles on it so far but a lot more going on now. I'll keep an eye on it, but I'm hoping it will be just fine.
05-29-2009, 12:03 PM
#42
Race Car
My rebuilt pump died with just under 60k miles. My new laso pump has been running now for a couple of months and 2k miles. I'm keeping my fingers crossed...
Dan
'91 928GT S/C
475hp/460lb.ft
Dan
'91 928GT S/C
475hp/460lb.ft
05-29-2009, 12:18 PM
#43
928 Collector
Rennlist Member
Rennlist Member
05-29-2009, 01:37 PM
#44
Rennlist Member
05-29-2009, 01:42 PM
#45
928 Collector
Rennlist Member
Rennlist Member
Try installing a bigger bearing into that thin housing. There is not enough thickness for that. Take a look at the water pump for ANY OTHER VEHICLE ... I challenge you to find me one that is as thin. Especially since most water pumps run off a separate belt, not one that drives the entire engine and valve train, oil pump, tensioner, both cams. If you think the housing is thin, look under the impeller, the housing is only a couple of millimetres thick there. Imagine holding that little impeller shaft in the V between two of your fingers. How long will you be able to hold it, with all that stuff pulling on it? Now imagine holding it in your fist. A little different, yes?