Jetdriver69

Can anyone tell by these pictures why this WP started leaking? It was a gusher from right behind the harmonic balancer. No other leak sources I could find.

There is some suspicious staining around the impeller, maybe that was the source?

The gasket DID NOT have RTV when it was reinstalled.

I will use a thin bead on both sides of the new gasket and install on the block before putting the new Laso pump back on.

Thanks!

JET951

Turn it over , you will find the leak from the breather hole ( behind the cambelt driven water pump pulley ) , there will be a leakage stain coming from behind the pulley

By the way , this pump has worn in the normal "old age way " meaning the impeller has worn into the alloy waterpump housing , I know it looks as if it is meant to be like that , but when new the impeller sits up / proud of the alloy housing , meaning it has machined/ cut itself into the water pump housing by the fact the waterpump bearing has worn via the tension load of the cam belt over years & engine hours of operation, this is the normal wear & this means the impeller moves to the front away from the engine crankcase

Jetdriver69

On further inspection, the old pump pulley bearing is very stiff.

Not even close to the smoothness of the new pump.

The new old belt has evidence of some WP pulley scoring.

Guess Im lucky she sprang a leak about 2 miles from my house.

WP is in and the RTV is curing for 24 hrs.

One cam gear was very easy to get off and the other needed a gear puller

As soon as I get the left cam gear off, steel ones go on. I'm afraid to even show a picture of the very worn alloy gears, they got to be the worst in the history of the 928.

mark kibort

the gears don't seem to wear if the tension is correct. most wear examples are from a belt that has been over tensioned.

how are you going to tension the belt? kempf tool ? what year is your car? what style pulleys? new HT version or old square tooth?

Imo000

Why are you using RTV and a gasket? Should be just a dry gasket and nothing else.

soontobered84

You need to post a thread asking for pictures of the worst cam gears. I'm sure that Stan, Sean, Doc Brown, maybe even AO, one of those guys would win the prize for the worst. That would be very interesting.

Hilton

This.

Please don't glue your engine together with RTV, it sucks to be the next owner of someone who did that.

If you need to use any sealant for your peace of mind, or because the sealing surface is damaged, something like permatex no 3 aviation non-setting sealant is good - can be cleaned up with solvents (e.g. acetone), but the factory procedure was to use nothing, and that works fine on a car which hasn't been buggered up by PO's.

Jetdriver69

I do believe the PO had the belt way too tight, but the damage was already done.

It is a 82, now steel cam gears, square tooth all around, yes will use a Kempf tool.

The old WP pulley will barely turn, let alone spin freely. If the belt can't easily turn the WP, then I would guess some scoring would happen to the belt.

SeanR

That's another of those $108.00 crap rebuilds.

And FWIW, I use a thin bead of Victor Rienz on the WP gasket. Others don't, some do, I like it.

Jetdriver69

That's what I did, very thin coat on both sides of the gasket.

Can't hurt and it may help....

Mrmerlin

I use a thin coat of RTV on both sides the water pump gasket ..........WHY?

Because when you remove the WP and gasket next time,
it will not stick to the block and make it necessary to spend an hour scraping the sealing surface.

The RTV sealant also helps keep the coolant from migrating through the gasket material into the bolt holes.
NOTE thats why I also suggest to use Loctite PTFE non setting pipe sealant on the bolts.

hacker-pschorr

Any clue how long this pump was installed?

If this is how the crap rebuilds fail, how do the good ones fail?

Or is the train of thought that if you replace them in the proper interval you shouldn't experience a failure?

GregBBRD

Actually, that bushing between the shaft and the impellor, plus the sand casting identifies that pump as a Laso, "version 3" (the version just before the plastic impeller version.)

Water pumps are a hellish environment. It's a wonder they last for a month, much less for years....

Hot steamy water, millimeters away from a permanently greased bearing, separated only by a seal. If the seal "seeps" just a little tiny bit, the bearing gets "steam cleaned", the grease gets washed away, and that bearing goes bad in minutes.

That might be the definition of hell?

Jetdriver69

The failed pump was installed in 2009 but at 83K miles. Now I have 89000 miles.

I reused the pump when I had the engine apart last year, but the pump bearing looked to be in good shape and had zero leaks.

Should have replaced it when I had the chance, but was being cheap.

The first symptoms of a failure was what sounded like a slightly squealing belt. I checked the tension on the TB and all accessory belts were good.

I guess the bearing was beginning to seize and the sound was from a dragging TB. The old belt definitely had some score marks on the front side. The leak from behind the balancer started shortly afterward.

hacker-pschorr

Interesting

I've heard stories from seasoned mechanics of water pump failures with pumps that were re-used with a fresh timing belt. Not just with 928's but any car where the WP and timing belt ride together.
It's always been a theory, "I heard about...." since none of these mechanics will ever do a TB job without a WP so it's never happened to them

Theory is, when a fresh pump is installed with a new belt they are "broken in" together. This makes sense, the initial tension on a belt is tighter for the first few miles.

I've also wondered how many pump failures are related to an over-tightened belt. Problem is, this is virtually impossible to track.


Side note.....there was a time when rebuilt pumps were accepted, reliable and many cases better than "new" since the new suppliers were suspect (look up Greg Nettles explanation of OE, OEM, NOS etc...).

It all goes back to a gentlemen named Dick Jordan. His water pumps exceeded the quality of new. He was trusted with pump rebuilds for cars where new wasn't an option, like pre-war classics.
A long time ago, in a galaxy far away he did all the 944 / 928 rebuilds for the European Parts supplier juggernaut World Pac.
Dick also did all the rebuilds for Zimms Porsche Parts.

I don't know exactly when WorldPac switched from Dick Jordan pumps to some offshore sweatshop, but I've always suspected that's when the premature failed pumps started to pop up around the 928 community.

Meanwhile, 944 owners have been buying Zimms rebuilt pumps (by Dick Jordan) until this past year, when their supply of Jordan pumps ran out.

They ran out because Dick Jordan retired in 2012, and Zimms and whoever else relied on his services are now scrambling to find a replacement source for rebuilt pumps.

I talked to Dick Jordan on multiple occasions before he retired when I was doing the engine out belt service for my fathers Ferrari 355GTS. I had huge reservations installing a rebuild pump in such an engine, even though this pump doesn't run on the timing belt.

Dick and I discussed in great depth the 944/928 water pumps, I don't recall how many he claimed to have rebuilt but it was significant. Just supplying WorldPac alone is a huge account.
A few things he mentioned I found interesting:

• Lasso pumps are an inferior casting to OEM. He preferred OEM castings over Lasso, since he had to "build up" the bearing area of a Lasso before doing the rebuild and they could only be rebuilt once, while he could do multiple rebuilds on a Porsche casting
• He found it crazy that anyone would purposely install a plastic impeller over a metal one. He is not the only WP rebuilder I've talked to with the same opinion, which is also shared with a friend of mine who is an aerospace plastics engineer and a lifelong car nut.
• He claimed with all the 944/928 pumps he's rebuilt, an impeller "walking off" and damaging the block was never reported back to him. He could not say with 100% certainty it never happened, but when such a failure occurs people usually complain

Two interesting threads from the 944 world:

"How Long Do Waterpumps Last?"
https://rennlist.com/forums/924-931-...umps-last.html
- 10 years seems about right
- At 282,0000 miles my '88 is still on its 2nd Laso water pump... Not leaking yet, good cooling.
- 20 years on my rebuilt from Zims.
- The pump that I pulled off off the 86 that I'm rebuilding had some bearing play and noise in the bearing at 15k miles after install. I suspect the previous owner had overtightened the timing belt. The pump was a new Laso pump.

"Best Deal For A Quality Water Pump"
https://rennlist.com/forums/924-931-...ater-pump.html
- This thread talks about the dried up supply of rebuilt pumps from Zimms.