Bill Ball

No, not me. My car seems invincible.

Anyway, about a month ago another local owner, Jon, AKA JG928S4, came over because he was having intermittent timing belt warnings 25,000 miles after a TB/WP job on his 88 S4. We removed the right and left cam belt covers and checked the belt over and visible mechanicals and all looked good, although the cam gears were worn. The belt tension was right on the low end of the Kempf tool window. So, I snugged up the belt to about 2/3rds up in the window. All seemed good, but after running the engine for a few minutes I noticed there was a coolant drip that traced up to the water pump area. Pulled the left cover again and saw the drip tracking from the pulley area but nothing else notable. We test drove the car to get some lunch and back, observed the drips, which were not voluminous and decided he could probably drive home but we should do a TB/WP before any other driving. The car ran smoothly and made no unusual noises.

Well, an hour later Jon called me to report the car began to seriously overheat. I don't recall that Jon noticed anything else, like burning smell or smoke or squealing noises. He pulled over to let it cool down. He did try to restart it and got only a brief sluggish starter response. He had the car flatbedded home. I thought perhaps he had lost all his coolant or the pump impeller had come loose or the pump had seized, but being as there was no squealing noise, smoke or burning rubber smell, I wasn't that worried about the latter.

Today I went over to Jon's to do the TB/WP and this is what we saw.





















That's Jon in the last shot showing the belt "welded" to the tensioner pulley, even though the tensioner pulley was not seized and was otherwise fine.

Should Jon be smiling? Well, probably not but maybe so.

When I saw the belt today, which looked close to new last time I saw it, I was stunned. Pretty obviously a complete water pump seizure. But the belt seemed still intact (we could not yet see the debris down below), so I thought, "Whew, caught just in time!" Before we got the center cover removed and saw the pile of belt teeth around the crank gear, we started to turn the crank to align it to 45 degrees BTDC..... the crank moved but the belt and cam gears did not move. Uhoh, expletive delete. I only moved the crank a few degrees before I realized the ugly truth - the crank gear had stripped a bunch of teeth off the belt and the car was probably hosed valve-wise. Teeth were intact everywhere else, so the belt seized on the seized WP and the crank kept turning while the cams did not.

We had no choice but to proceed with a TB/WP job and then compression test the engine. We turned the crank to 45 degrees BTDC, about a quarter of a turn in reverse direction, carefully observing for but not feeling any valve contact and proceeded with the TB/WP job including lots of new gears and a PorKensioner.

After buttoning things up about 6 hours later, the car started and ran very smoothly, EXCEPT there was a rather noticeable "clunk-clunk" inside the engine, most likely a bent and stuck valve. Not the usual stuck lifter sound. I did not have my compression tester, so we will get to that in a couple of weeks. Based on the belt destruction I would have expected numerous bent valves, and that may be. Based on how well the car runs, he may only have two bad ones. The compression test will tell.

Yes, I know the coolant leak around the WP pulley appearing right after a timing belt adjustment probably should have set off a red flag, and it did. However, there was no evidence of anything else wrong. No bearing noise, no visible displacement of the WP pulley (although, in retrospect, it probably is not be detectable in situ, judging by the 3rd & 4th pictures above, before the pump was removed). We studied the situation for quite a while. We test drove the car 5 or 6 miles and found nothing wrong but the minor fluid drip. You can see obvious evidence now that the bearing pack failed and the pump shaft canted to one side and seized. The impeller made some minor contact with block, not serious enough to require repair (sorry, no pic of that). There was still the usual amount of coolant behind the water pump when we removed it and none dripped out despite sitting for a month.

Anyway this is a catastrophic failure of what appears to be a rebuilt Porsche water pump.

mark kibort

wow, lucky there wasnt more damage. I still cant get over the random, water pump weak link in our cars!
Bill, you are amazing. the jonny repair appleseed of the 928 world!


mk

namasgt

looks like there has been too many W-pump failures recently. I hope he can get his car fixed fast.
25000 miles, how many months or years ago was that ?

Leon Speed

Ouch, that is not good to see. What is with the residu on the impeller? Did the car stand for a long time?

Maybe the valve damage is not so bad. It could be that the belt fused to the tensioner pulley after the car was shut off at the side of the road and that the teeth near the crank stripped when trying to start it.

Never ceases to amaze me that no matter how big a problem is, the technical skill and help is there to fix it. "Regular" folks have it flatbedded to the shop and 3000 bucks later it is fixed.

Black Sea RD

Any more information on the pump? Where purchased, "Porsche rebuilt" or another rebuilt using a Porsche (?) housing, ect.

Mrmerlin

Sorry to hear the news Bill, I think from now on when the belt gets loose it might be wise to pay more attention to the WP pulley and its relation to the housing.
I was thinking that during the WP rebuild process is the housing heated and then the bearing pushed in? or is it just pressed in at room temp
Is any type of loctite applied to the housing or the impeller shaft?

FYI I would recommend that both heads be removed and inspected, that way the whole engine will be strong again IE new head gaskets

marton

WP foto looks like mine did when it siezed. Luckily my belt did not sieze on the WP.

Gretch

i worry about damage to the valve seats or guides. If it is making "noise" contact is prolly "occured where no man has gone before"..........

Bill, every time I see sombody open up one of these german hotrods, I am amazed how reliable mine has been. I have had new parts sitting in my shop for years, expecting to need them and crossing my fingers every time I fire the old girl up that I can spend more time driving than wrenching.......

I have been very lucky so far. She has been a garage queen now for about 9 years..... My 3 daily drivers ALL have more miles on them than my 20 year old shark!

I wish I lived closer to guys like you who work on them all the time....... I would enjoy hanging around and helping do the work. I am just greatful I don't HAVE to work on my own shark!

Imo000

Wow..... mine looked just like that when I bought it back in '00. Same story, pump siezed, crank chewed off the teeth but bent all the exhaust valves on the passanger bank.

With only one cyulinder out of commision it will idle amost perfectly but under load, you will definetly feel that the engine is out of balance and down on power. Can you guys feel this during test drive?

Lizard928

With regards to the pump, it looks to me as if the bearing cages failed allowing the shaft to simply rotate up and jam on the freed ball bearings. I also have seen one fail like this to. Thankfully the owner turned it of before there was any damage to the belt and or valves.

Garth S

That is exactly how the pump failed on my ex '88S4 - the bearing cage failed, and belt tension pulled the shaft sideways, letting the pulley eat away at the pump housing: the impeller in mine was plastic, so no internal damage as it broke free to 'freewheel'. Fortunately, it was caught early and the engine S/D as both the belt tension and water temp alarms came in almost simultaneously .... almost as fast as I hit the key

Strange thing on mine - the pump seal did not fail, so the pump never lost a drop of coolant .... nor did it give any early warning.

ROG100

Another case of a rebuild failure. The common denominator is the company that rebuilds the water pumps for the after market is the same company that rebuilds them for Porsche.
This further strengthens my decision to only use new Laso pumps on my cars.
New is good, rebiuld not good.
Still a weak point in our cars.

LightStriker

Sorry for the lack of knowledge of that... But what fail in those pumps?
Couldn't some our of great parts maker make a bullet proof pump? Or maybe just the part that keep breaking down in those pump?

If it's most of the time the bearings, aren't there stronger bearing out there?

cali4sun

Sorry to hear about Jon's car. Makes me concerned as I put in a TB/WP recently and the WP was a rebuilt. However, car is a garage queen, and it only gets out one day on a weekend..... Thanks for the thread. Good info!!!

'89 S4 GP White/Black
'76 912E Silver/Black sunroof

Objects in mirror are losing

Bill Ball

The residue looks like grease, but is too hard. Initally I thought it might be excess gasket sealant from overzealous application on the WP gasket, but the gasket had very little sealant and it was a different color. So, it may have come from somewhere else. Anyway, I couldn't figure that out.

Yes, that is a likely sequence. The fusion of the belt was stronger to the tensioner roller, despite it being perfectly free turning, than to the WP pulley. The belt was worn down to the reinforcing cord and got so hot it stuck to the cam gears as well, although it peeled off them pretty easily.

Yes, I think it is quite likely there is only limited valve damage. i have a beed on a used head in good condition that could take care of the problem cheaply and quickly.