atb

This water bridge came off of an '84.
Notice how the casting broke on the interior rim leaving the O-ring exposed.



I had no explanation for this, until I called up Ken Osage to see if he had a spare. He did, we went over to get it. When Ken pulled it off the shelf we showed him the failure on the original part, and upon inspection he noticed that the replacement part had actually started to fail in the same location. Notice the crack to the left of the red line. (Sorry for the poor phone pics)




The owner was told that the O-ring gaskets for this style water bridge were NLA. You think Porsche is trying to subtly suggest that the owners of these 928's need to use an earlier waterbridge with the paper or metal gaskets?

Anyone else see this kind of failure?

atb

I should mention that we drained the coolant, and didn't happen on the part. (Didn't pull the WP though). The owner isn't too concerned about jamming a WP since its a 16v motor.

Ketchmi

Hey Adam, I just epoxy fill the gap and use a paper gasket. Use a good epoxy and you will be fine.

atb

It's funny you mention that Dave (or Garrity lurking as Dave ), Ken actually had a second water bridge where someone did just that. Filled the channel about 90% with JB weld leaving a very shallow channel for the embossed portion of the paper gasket to fit in.

I ended up just rebuilding the original with JB weld, but at some point I imagine all of these water bridges will need to be epoxy filled to use the paper gaskets.
Here's the repaired original w/JB weld built up to reform the flange:

linderpat

what happens if over time that jb weld breaks off inside there and gets into the internal cooling system? Is that a concern?

atb

Hi Ed,

I would think that anything that floats loose in the water system has a chance of seizing up the water pump. Definitely a concern on any of the 32v motors, not so much on the 16v'rs like this one.

This particular owner is using this just as a temporary fix. He had been without his car for a few weeks and really wanted to drive it. (Finally getting some nice weather up here in the PacNW) I don't know if he'll replace it with the same, or go for an earlier model that uses the paper gaskets, and tap out a Temp II sensor bung.

UKKid35

When did they stop using O rings?

slate blue

I actually welded mine and had it machined, N.B this was on a 16V engine in which we had to shave the heads a lot to regain the comp due to the port work. I would also have concerns about bits breaking off, this the damage should only be minor though and it would only break off if you didn't clean the contact area of all corrosion and then fail to keep the coolant levels correct to avoid corrosion problems in the future.

Greg

PortlandTom

So now you guys have me worried. Are you talking about all 928s or just 16Vs? On the intake job on my GTS, I took off the coolant bridge. It had an o-ring on each side, along with the residue of what looked like paper gaskets. I ordered replacement gaskets according to the PET, and received new o-rings (not as thick as your pictures show). That's all I used to put the coolant bridge back on. Should I be using a paper gasket?

Thanks,
Tom

Ketchmi

Hey Tom, you have nothing to worry about. S4 and later engines used a different style that has not failed as far as I know.

atb

That's right Dave. The "O" ring on the late 16v motors is shaped like a rectangle and is very thick. The 32v motors use one that is more rounded and thinner, and I think there was a tech bulletin in 1989 that recommended the use of the additional paper gasket with the O-ring, but I don't think its necessary.
I don't think the later model bridges are cast in a manner that creates the same weakness.

PortlandTom

Thanks for clearing up that question. This job has really taxed my capabilities - don't need anything more to worry about.

Tom

atb

Nothin' a beer, brot, and kraut won't cure, going to the Rheinlander on 6/7?

PortlandTom

I'm going to try to make it. Haven't checked with the wife yet. I may even have the GTS running by then. Turns out I had a couple incorrect parts, so now I'm waiting for parts again. (928.107.733.02 isn't the same as 928.107.733.01.)

I didn't mean to sound discouraged, though. I just get worried that I missed something when I see threads like this.

Tom
982 GTS, 5sp., Amazon Green