SQLGuy

Hi folks,

I seem to have a slow coolant seep from the bottom of the front crossover. Is this common?

How much of a job is it to change out the O-ring down there?

Thanks,
Paul

Stromius

The was a technical bulletin that had you add an extra gasket along with the O rings. https://rennlist.com/forums/928-foru...lly-fixed.html

SQLGuy

Hmm... mine is not in the S/N range for affected engines; also, I'm pretty sure mine is seeping up from the big tube in the middle, not leaking from the side ports where the extra gaskets are indicated. I'll keep an eye out for extra gaskets when I get into it, I guess.

Although, I also see that Dwayne was experiencing a leak on an '88 as well, so I'll also be taking a closer look to make sure of where the leak originates.

Bill Ball

Yes, that o-ring gets brittle and leaks. You need to remove the intake manifold and oil filler neck. Technically you don't absolutely need to completely remove them. IF (big IF) the intake and all the underlying vacuum and breather hoses are in good shape, you can unfasten the intake and LIFT it w/o completely removing it, enough to get to the oil filler neck bolts. BUT if the intake area has never been touched, this is a great time to refurbish that and replace the filler neck seal.

Mrmerlin

check the hose ends for splitting if the hoses are old,
and if they are new then tighten the clamps, this has fooled more than a few people

jthwan22

You don't need to remove the IM to get to the water cross over. You do need to remove the front fuel line and fuel damper. I am doing this job right now.

Bill Ball

You can get the water bridge out out with the "IM" and oil filler neck in-place? Maybe my memory is faulty. I did it a long time ago. I can't check it now because my car doesn't have stock filler neck or IM. But I guess it could tilt forward and clear the oil filler, but I thought it couldn't. Sorry if I mislead anyone.

Tails

I had the same problem, so removed the bridge and resealed with a silicone gasket maker around the "O" ringand replaced. I then purchase a new "O" ring and thermostat seat ring which is now on my job-to-do list.

Suggest that you purchase a new "O" ring, two landing gaskets and the thermostat seat and "O" ring IIRC.

The job is basically straight forward however it can be a little difficult in removing the one of the set bolt on the RHS of the bridge, as you cannot get a direct axial alignment of the allen key with the set bolt head.

There is numerous threads on removing the thermostat bridge to renew "O" ring etc., so remember the "search" is your friend.

Tails 1990 928S4 Auto

Jascd

Its fairly common to break at least one of the waterbridge bolts in the process, if that happens then you will need to remove the intake to fix. I suggest you put up with the seep if its not too bad until you can do the intake and the bridge at the same time.

davek9

I just completed this on an '87, you won't need to remove the IM.
Make sure you get a good fit in the alens w/ the wrench they may be rather tight.
Also replace the rubber seal on the bottom of the filler neck while you are right there (they all leak) a little sealant won't hurt.

SQLGuy

Cool. Thanks for the picture.

Cheers,
Paul

WICruiser

Before you tackle the bridge make sure that it is not one of the many hoses in the area. When I did my intake refresh I powder coated the bridge, replaced the o-ring and gaskets, thermostat seal, etc. but then had coolant pooling in the large o-ring area.

I was about to go back in when I realized that one of the smaller coolant hoses had cracked and was leaking into the area.

I knew I should have replaced the hoses when I did the rest but I was glod I found it before I pulled the bridge out again.