Water bridge leaking
 

I finally put everything together on my engine after a head gasket failure. When I filled the cooling system, I noticed it was leaking somewhere. After some research, I found out it is the big neck with huge rubber O-ring from the water bridge sticking into the block that is leaking.

I think it's a very strange and vulnerable construction. Has anybody else experienced this problem? And are there improvements to be made to prevent leakage here? I have a 16 valve engine.

The o-ring and the rubber gaskets on each side are prone to leaks and it's very common to have small leaks in that area if the o-ring/gaskets are not renewed. Did you replace them when you worked on the head gasket?

I assume that on a 16V it's very easy to remove the bridge. I have a snapped bolt in bridge of 32V and have replacement gaskets to install when I remove the bridge and assess state of snapped bolt but will probably move intake back a few inches to give a little more room needed for the 32V.

Replace the big O-ring and the two gaskets on either side, the O-ring on the front of the bridge and the O-ring between the thermostat and the bridge, and you're good to go!

Aryan, do I understand correctly there are 5 seals/gaskets/O-rings in total?
I know of:
- 2 of them going to each cylinder bank
- 1 going straight down, into the block
- 1 between bridge and thermostat housing
- The last one?

In my rush to have the car finished, I forgot to replace them. They also looked okay, but apparantly they're not...

So nobody has had problems of leakage with new seals?

I hope I did it right to show the gaskets. I did this last week on mine after finding the valley below the bridge filled with coolant. After sucking it up 3 times I decided to remove the bridge and replace the 5 gaskets. By the way, my gaskets were only 1.5 years old and the leak came from #25 the same one that's leaking on yours.

HK

Hi Hessank,

Did you pull intake to remove the coolant bridge? I will probably need to lift the intake as bolts on my bridge corroded and already snapped one (want good access to the bolts so that I can get heat on them and avoid snapping another) but always interested in experiences.

One thing I feel like should be mentioned is that you will not want to dry fit those O-rings either. Just like an oil filter they should be moistened with the fluid that will be in there (in this case coolant) to give you a good initial seal.

My guess is that even though the old ones looked fine, they dried out while you were working on the rest of the car and then they didn't seat properly when it was all reinstalled.

That big center O-ring (#25 in the diagram above) is really tight when it's new. If it was easy to install without really working the bridge down then it wasn't going to do its job.

No, you do not need to remove the intake (even though the picture has the intake removed). The bolt marked with the x is a pita but use a box wrench to turn a long allen wrench and it will come out easily. I also had to "help" the bridge to come out by using a long screwdriver to force it out of that bottom gasket.

HK

Thanks Hessank - that's great detail

This kind of failure is common on the 16v motor.

Between the bridge and the thermostat.

Hessank,

What's your engine number on your '89?

There's a service bulletin from Porsche about some '89 engines requiring an additional gasket for each of the side flanges on the coolant bridge (uses the same gasket part no. as the rear head plates for heater valve etc.).

(my '89 has one of these affected engines)

See attached image:

Hey cool, didn't know that. Luckily my engine serial number is 07435.

Serial # is 0992. Looks like I am exempt. Mine leaked from the large O-ring after one and a half years, whick was 3 weeks ago since I had changed all the gaskets.

Today I bought all the new seals for the water bridge. The red rectangular O-ring is still available at Porsche by the way, although the dealer made a mistake and ordered the previous design seal, being a flat gasket. Luckily a Porsche specialist nearby had another one and removed it from an otherwise complete gasket set. I also have the problem of the partly disformed alloy inside the seal but I will add some sealant paste to overcome this problem.
I also bought some stainless steel allen bolts to replace the standard ones after reading all those horrible stories of snapping of bolts. To prevent extra alloy corosion due to the difference of material, I will add copper paste.