Tim968

'92 GTS ex-Japan, 65,000km, likely had its first coolant change at 2004 with about 40,000 km (as near as I can tell from Japanese-language service parts lists). I swapped it out to Xerex and distilled at 60,000km in 2011.

In 2004, someone put both the silicone formed ring AND a paper gasket under the water bridge, with ugly pitting corrosion resulting - took some 600grit and WD40 to clean it up. I understand that this waterbridge gets a fair bit of differential thermal expansion...Dwayne's Norcal writeup is my basis of overhaul method.

QUESTION; what is the consensus on this connection? Pits are small but will catch a fingernail easily. Go with stock red silicone gasket dry, or red silicone gasket with supplemental goop (like Loctite 515).

All replies appreciated. Thx/Tim

Ed Scherer

The thread '88 Coolant Leak Finally Fixed! might be helpful to you. It discusses the TSB explaining the double gasket. IIRC, I just used a little Dow Corning 111 (or equivalent) on the gasket that goes into the channel (and used the paper gaskets as well; my '90 had both when I took the bridge off) and it's been holding just fine for more than two years.


Edit: actually, I see that I did use something after all (on the paper gasket) at another Rennlister's recommendation: Permatex 98H/98D 80062/80063 High Tack Gasket Sealant.

SeanR

I usually just use the red "o-ring" and nothing else there unless the surface is pitted like you have. It will not hurt anything if you put small amount of RTV along the surfaces along with the paper gasket though.

Tim968

Thank you, Ed and Sean. Much appreciated. Thx/Tim

Mrmerlin

before you attach the water bridge test fit it and use a feeler gauge without any gaskets or seals ,
see how its mating ,
if the heads were cut then the angles will change.
There was a TSB to use 2 gaskets per side,
if you use any RTV let it cure 24 hours before you add coolant.
Its also a good idea to use the Dow Corning 111 on the fat O ring,
this will keep it soft and let it slide easily into position.
also works well on the O ring for the thermostat.
Amazon sells DC111

Make sure you fit a rear thermostat seal or you will have overheating issues

Tim968

Thanks, Stan.

GregBBRD

I, personally, got tired of leaks in this area. Every single one that I have to redo, happens on "my own time"...so I was forced to come up with a method that worked each and every time, flawlessly.

If you can "dream it up", I tried it. Silicone gasket with and without sealant. Paper gaskets, with and without sealant. Different sealants, different gaskets.

I use the red silicone factory seal, a factory "paper" gasket (same part number as used in the rear), and use a thin layer of Porsche factory Drei Bond on both sides of that gasket.

Never have had one leak with that combination....been doing it this way for about 6-7 years now.

Tim968

Thank you, Greg. I worked the feeler gauges and tried to gently sand the faces on the bridge-to-head flanges into parallel fit, but ~0.004" gap on LH front of flange remains, and is the best I can manage. Your advice is timely, as I am fitting the GB oil deflector baffle and they have to go in pretty much simultaneously. This advice is much appreciated!