mark kibort

I totally agree. I have almost as many bad new pumps, or pumps that wore out prematurely, to good used pumps.

my pump is staying there until it makes noise or starts leaking. I had one new pump recently that made a strange sound only on start up. when i pulled it, it was just a little loose at the bearing. if the pump is working well, i would leave it in there. also, have we talked about putting a roll pin in that darn shaft and impeller??? how about a little Mig Weld right across the shaft and impeller?

by the way, JVs failure was just the opposite. the outside pulley came off the shaft. thats even worse. timing belt goes and so do valves. id rather have the marks on the block than to replace 32 $30 valves and have to pull the heads!!!!

Weld it all up!!!

mk

John Veninger

Nope, just as Mark stated. My impeller was just fine. The bearing was also just fine!

mark kibort

Can we just put a quck weld on both sides of the shaft to prevent this kind of failure?

How many racing days, engine blocks, valves, labor hours, $$$, do we have to loose to this kind of failure??

ZEUS+

This happened on my 84 back in 97. Smoothed grooves with a roloc disc and still fine to this day.

marton

Mark posted
That is the point really, that pump shifts an awful lot of water; if the loss of some metal should reduce the pump efficiency then I do not see that as being an issue.

If you are worried then after you install a new pump & before you put on the auxiliary belts & button it up try temporarily replacing the heater hose (the one with the plastic valve) with a transparent plastic hose - then you can start the motor & see the water flow. At 2000 rpm it is like a garden hose.

Marton

Mike Frye

John,

What I meant was to ask if the shaft went in toward the block with the impeller or did the impeller blade come off the shaft like your pulley did?

I'm trying to figure out which end (if either) is attached to the shaft. Clearly in your case the pulley showed it is only pressed on. I wanted to know in the OP, what was attached?

When we were at SP, you were thinking of pinning it or welding it too, I'm trying to figure out how to deal with this preemptively.

BTW- When I replaced my leaking WP gasket a few weeks ago I put a dab of paint across the pulley to shaft connection and I plan to check it after a few thousand miles to see if it spins at all.

John Veninger

good idea!

Imo000

Spot welding both end with a mig is a good idea but when times comes to get a new pump, the old one will not be acepted as a good core.

John Veninger

Worth 10X the core charge for the front pulley not to come off!

dr bob

The heat from welding may or may not damage bearings and seals. Get the right pump and sleep better.

mark kibort

whats the right pump???? ive had them all fail once.

(i dont know if i have got a pump from 928 international though! )

new with plasic, new with metal, rebuilt with metal, by the good guys, by the bad guys. so many , so many falures, ive lost track.

i think a quick mig weld is the answer.

Mk

Mike Simard

I'm not sure welding the pulley would be reliable. It's possible that a failure like that has something to do with crankshaft harmonics being transmitted through the timing belt.
It's a given that crankshafts go through some whacky rotational funk if the damper isn't up to snuff and everyone has been using 20 year old dampers intended for a 5 litre motor on their stroker builds. I don't know if the crank damping could have an a real effect on the timing belt accesories, just thinking out loud here.

I still don't trust a weld to hold, it just doesn't give me a warm feeling, I can picture it fatiguing easily. A proper interference fit is the only way to reliably hold a pressed pulley on a shaft, it's also tricky to get the correct fit AND have it be pressed together without incident.

Mako 928

So as far as finding a good replacement water pump what should you look for? I bought a pump from one of the big 3. The casting # is 928.106.122 the roller has #928.106 /19005. So I assume it is a rebuilt pump. It also came W/ a photo copy of a warranty W/ a lot of disclaimers one section read "Rapid engine acceleration particularly in low gears during quick get away impose heavy overloads on the bearing. This can result in severe whipping action and sudden fracture of bearing shaft" The warranty seems to come from "Automotive parts center inc." "APC" Does this sound like a good pump? And who the hell does'nt do a "low gear rapid engine acceleration" in a 928?

Mike Simard

Wow, that's very interesting. They didn't say free revving the engine but mentioned "particularly in low gears". That implies that they might know something about crankshaft harmonics like I wondered about ealier.
Of course they could also be spouting generic warnings too. I wonder if they ever had a failed pump and asked the customer, "say, you didn't accelerate rapidly in low gear did you?"

Bill Ball

Both side are press fit.

The pumps are not part of the maintenance schedule, but it has become essentially a standard procedure to replace it at each TB job each 60K miles. There are no compelling statistics on this. The return rate on rebuilt pumps is said to be very low, but we here of multiple problems here. My original water pump was not replaced by the dealer when the TB was done at 60K miles for the PO. When I did the next belt I replaced the pump. It looked and felt brand new. It seems to be a toss up to me. If someone wants to replace the pump or skip it, I don't argue with them.