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By captainOCD
#79239
So I've got my intake more or less torn down currently. I got the water bridge cleaned up and was getting ready to put it back on, then I noticed I have both gaskets and o rings in my box from Roger. Searching around I see some conflicting info. Some people say just use the o rings. Some people say use both.

What I do know is that my waterbridge only had the o rings, and it didn't seem to be leaking. What would you guys do? Just use the oring or use the gaskets too?
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By worf
#79249
I use red seals and paper.

A couple of years ago, I was distracted and forgot the paper seals.

Got to do that job the second time for free.

If you feel “antsy” about the paper, then use red seals and goop.
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By worf
#79254
Wait: this is an S3? On S3, I've done red seals and goop.

The 'extra' paper seals are 'approved' for S4s at a certain VIN but can be 'retrofitted' to older S4s.

S3? Dunno.
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By captainOCD
#79269
Yeah, this is an S3 (86.5).
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By Geza-aka-Zombo
#79275
Prior to doing my intake refresh, I had a slight water leak with the bridge at the right side. Turns out, the water bridge casting had some porosity that was exposed when the groove was machined in leaving a void area at the seal, enabling coolant to pass by the seal. I cleaned out the void and filled it in and smoothed it out. I used the seal only for my installation, as this is what was there when I removed it. No leaks.

Check the seal grooves for flaws and make sure they are clean.
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By Adamant1971
#79306
I also use both, especially if the matting surfaces have any corrosion or pitting. Plus I use a light coat of RTV on the paper gasket.
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By MFranke
#79395
I've not seen the paper and the o-rings together for the water bridge on S4s. On disassembly of factory installed water bridges, it was o-rings only and no sealant. The gaskets are for the coolant lid and adapter. This appears consistent with what is shown in the parts diagrams. Not sure if there is a bulletin on this or something, but fwiw, never had a problem using just the o-rings on the water bridge.

...Just occurred to me that decking the heads, or uneven head height could affect bridge fitment. If your heads are original height and the o-rings were working, then if it were me I would feel fine continuing with that. I suspect the gaskets could help if there are fitment or roughness issues.
Last edited by MFranke on Tue May 11, 2021 5:50 pm, edited 1 time in total.
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By worf
#79396
MFranke wrote: Tue May 11, 2021 5:20 pm Not sure if there is a bulletin on this or something,
There is.
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By captainOCD
#79399
So inspecting the ring grooves and the heads, I found no sigs of pitting or scratches. The new o rings seem to sit well proud of the surface of the water bridge as well. That with it seeming as the gaskets may have been more of an S4 thing, I've gone ahead and installed with just the o rings and a bit of rtv smeared very lightly on the surface of the ring. Some rtv on the bolt threads as well.

I'm still not quite to putting the intake back on, but I'm thinking I'll go ahead and top off the cooling system tonight, then leave my pressure tester sit on it for a day or two. I'd hope that would show leaks if they are going to form.
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By worf
#79440
captainOCD wrote: Tue May 11, 2021 5:40 pm I'm still not quite to putting the intake back on, but I'm thinking I'll go ahead and top off the cooling system tonight, then leave my pressure tester sit on it for a day or two. I'd hope that would show leaks if they are going to form.
Good. Always pressure test once the cooling system closed.

If you've filled it, you'll know in minutes if you have a leak.

If you haven't filled it, you'll still know in minutes if you have a leak, but it will be harder to find 'cause you gotta get out the spray bottle of soapy water...
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By captainOCD
#79452
It's been sitting with ~12psi in the system for several hours so far. No leaks around the mating surfaces of the water bridge to the cylinder head to be seen. Only leak I've found is this hose from the water bridge to the coolant bottle. I have some new heater hose that will take care of that though. At least if nothing else I know there is water past the level of the water bridge to head connections.
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By MFranke
#79463
I got curious so I looked up the bulletin. Looks like the gasket could help if you have developed tolerance issues. It appears some came from factory this way due to tolerance on certain engine runs. Glad to see leak test going well. That little hose and the one below it seem to always need and extra round of tightening on my cars.
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By captainOCD
#79731
Welp, sat overnight and no leaks apart from that hose, which has been corrected now. So it seems like o rings + a smear of rtv works for this car.
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By SeanR
#79759
You are going to want to have some heat cycles going before you declare victory and may also need to retorque those water bridge bolts after a few weeks.
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By maddog2020
#79782
I filled the ring groves with epoxy, and used the paper gaskets with a ghost thin coating of RTV on both sides of the paper gasket. Filling the grooves gives a larger surface for good gasket sealing.
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