Recommendation for Camshaft Bearing Cap Sealant?

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April 23rd, 2020, 16:07
SFJ_RS6

Recommendation for Camshaft Bearing Cap Sealant?

I'm working on replacing cam seals and cam tensioner seals and plastic guide/pads. According to Bentley it looks like the camshafts need to be removed to change the guides.

Does anyone have a recommendation (preferably experience-based) for a proper sealant to use on the end camshaft bearing caps that need to be sealed to the top edge of the cylinder head? Bentley says a sealant should be used but doesn't specify, referring to Parts Catalog which I don't have.

I've done some research, and agree with others that RTV isn't a good choice due to film thickness affecting bearing clearance. I've seen Permatex Aviation Form-a-Gasket #3 recommended, and something called Hylomar, both of which are supposed to create a thinner film.

I don't have experience with this part of my cam chain tensioner guide/pad replacement, and would appreciate input.

Thanks,
Steve
April 23rd, 2020, 23:01
Muggy

Interested to know here too...this project is on my horizon. I did get a lime green glow in the dark stuff when I did my son's A4 when we had to pull the cams out...it was a VW/Audi product and expensive as hell, like $100 a tube. It seems like a really thin sealant for these types of parts...If I remember correctly, it was to go under the cam girdle for metal on metal parts.

This may be the Hylomar product that you are referring to. Unfortunately the labeling is in multiple languages for safety issues only...

http://www.fototime.com/3000A05C417643C/medium800.jpg
April 23rd, 2020, 23:04
GreggPDX

Quote:

Originally Posted by SFJ_RS6

I'm working on replacing cam seals and cam tensioner seals and plastic guide/pads. According to Bentley it looks like the camshafts need to be removed to change the guides.

Does anyone have a recommendation (preferably experience-based) for a proper sealant to use on the end camshaft bearing caps that need to be sealed to the top edge of the cylinder head? Bentley says a sealant should be used but doesn't specify, referring to Parts Catalog which I don't have.

I've done some research, and agree with others that RTV isn't a good choice due to film thickness affecting bearing clearance. I've seen Permatex Aviation Form-a-Gasket #3 recommended, and something called Hylomar, both of which are supposed to create a thinner film.

I don't have experience with this part of my cam chain tensioner guide/pad replacement, and would appreciate input.

Thanks,
Steve

When I did it, I'm pretty sure I just used blue RTV. I don't remember exactly why I chose that sealant, it's possible it came with the Blauparts kit that I used. I guess I don't understand how the sealant thickness would affect any bearing clearance there. Are you talking about the little gasket that goes between the tensioner assembly and the head? I remember that the manual suggests applying small amounts of sealant on that gasket, and I also recall that there is an oil passage through that gasket with a small screen. I was very careful to make sure that I did not use too much sealant and have it "squish" into that screen and potentially block oil flow. FWIW, I did this about 2 years ago, and no leaks!
April 23rd, 2020, 23:14
Muggy

It looks like the green stuff is for metal on metal....

From another site:
vw/Audi sealant d154103a1
"It is a green anaerobic sealant used to seal the aluminum to aluminum camshaft girdle on the newer engine"
April 24th, 2020, 00:40
bethridg

Y'all are over thinking it. Grab some Permatex Ultra Black. Spread a thin film around the cam seals, cam end cap seals and half moon seals (including the flat). I add a little more sealant to the tensioner gaskets in all the spots where sealant was applied from the manufacturer. Be mindful of the oil passage and screen on the tensioner GreggPDX mentioned. For the valve cover gaskets you only need a dab in the corners and valley where the cam caps and tensioners meet the head.

If the Blau kit came with a tube of sealant that will be sufficient.

Edit!!!

I just realized you're talking about the cam caps themselves and not the end plugs at the back of the head provided in the gasket kit. I DO NOT use any sealant between the cam caps and head surface. Only around the seals and end plugs.
April 24th, 2020, 03:37
SFJ_RS6

Thanks to all for your inputs!

Quote:

Originally Posted by Muggy

It looks like the green stuff is for metal on metal....

Sounds like Audi/VW green gold - very typical for them!

Quote:

Originally Posted by Muggy

From another site:
vw/Audi sealant d154103a1
"It is a green anaerobic sealant used to seal the aluminum to aluminum camshaft girdle on the newer engine"

I'll try to estimate the consistency of the green stuff in your photo compared with my Loctite 518, which I've used for AL metal on metal seals in turbos.

Quote:

Originally Posted by bethridg

Y'all are over thinking it. Grab some Permatex Ultra Black. Spread a thin film around the cam seals, cam end cap seals and half moon seals (including the flat). I add a little more sealant to the tensioner gaskets in all the spots where sealant was applied from the manufacturer. Be mindful of the oil passage and screen on the tensioner GreggPDX mentioned. For the valve cover gaskets you only need a dab in the corners and valley where the cam caps and tensioners meet the head.

If the Blau kit came with a tube of sealant that will be sufficient.

Edit!!!

I just realized you're talking about the cam caps themselves and not the end plugs at the back of the head provided in the gasket kit. I DO NOT use any sealant between the cam caps and head surface. Only around the seals and end plugs.

Yes, correct - I did mean where the aluminum cam bearing caps mount to the aluminum head surface (metal-to-metal). I think I will use come sealant in those metal to metal contact points that need to hold oil as recommended in Bentley.
April 24th, 2020, 03:39
SFJ_RS6

Thanks GreggPDX! I see that little screen and will try to avoid getting seal in it.
April 24th, 2020, 03:49
SFJ_RS6

2 Attachment(s)

Left side cam chain tensioner out

I got the left cam chain tensioner out today. First time job, so I learned by doing, and eventually got it out. Hopefully, the right side should go quicker.

Some grooves worn in both the top and bottom guides/pads. Not too bad but I'm glad to get them refreshed. The half-round seals were leaking, of course. They don't seem like a great approach from my experience and others that I've read here.

Blau kit with pads due to arrive in a couple of days, and I'll be on the replacing the pads and reinstalling.

https://www.rs6.com/attachment.php?a...id=19187&stc=1 https://www.rs6.com/attachment.php?a...id=19188&stc=1
April 24th, 2020, 11:24
Muggy

Appreciate the follow ups and pics...how many miles on your car? I don't have any oil leaks from the top side, but feel like I have a sloppy chain due to aging pads (105k on my originals).
April 24th, 2020, 18:13
kruat

What caused you to look into changing the cam tensioner pads? How many miles do you have?
April 24th, 2020, 21:04
SFJ_RS6

I have about 92,000 miles on the car. As to why I'm changing the pads, it preventative. I've got the engine out to replace O2 and EGT sensors. While I'm at it, and having some slack time due to CV stay-at-home, I'm trying to chase down and plug all oil seeps and leaks. Had some leakage various places on cylinder heads - valve cover gasket, cam oil seal, cam chain tensioner, half-round plugs. So while I've got the valve covers off I decided to do the work to replace the pads.

Steve
April 24th, 2020, 21:46
GreggPDX

Quote:

Originally Posted by SFJ_RS6

I have about 92,000 miles on the car. As to why I'm changing the pads, it preventative. I've got the engine out to replace O2 and EGT sensors. While I'm at it, and having some slack time due to CV stay-at-home, I'm trying to chase down and plug all oil seeps and leaks. Had some leakage various places on cylinder heads - valve cover gasket, cam oil seal, cam chain tensioner, half-round plugs. So while I've got the valve covers off I decided to do the work to replace the pads.

Steve

Mine were done around 82K miles while the motor was out for the trans swap, and they looked almost exactly like yours. A bit of wear, but not bad.
April 25th, 2020, 17:32
lswing

Quote:

Originally Posted by SFJ_RS6

I have about 92,000 miles on the car. As to why I'm changing the pads, it preventative. I've got the engine out to replace O2 and EGT sensors. While I'm at it, and having some slack time due to CV stay-at-home, I'm trying to chase down and plug all oil seeps and leaks. Had some leakage various places on cylinder heads - valve cover gasket, cam oil seal, cam chain tensioner, half-round plugs. So while I've got the valve covers off I decided to do the work to replace the pads.

Steve

That pad doesn't look horrible really, but it's go wear for sure. Maybe your car has experienced lower operating temps. Mine, and many others, have failed in the last few years due to age, temp, and mileage.

There's info on my website about soldering the egt's, and possible saving a chunk of cash. You can also google this site for some good threads on it. Even your new egt's could prematurely fail and the solder fix might keep you going.

I take it you've done the oil/coolant pipe? Known as Bufkin...

Cam seals and valve cover are notorious for small leaks, off and on, all the time it seems.
April 27th, 2020, 01:00
SFJ_RS6

Quote:

Originally Posted by lswing

That pad doesn't look horrible really, but it's go wear for sure. Maybe your car has experienced lower operating temps. Mine, and many others, have failed in the last few years due to age, temp, and mileage.

There's info on my website about soldering the egt's, and possible saving a chunk of cash. You can also google this site for some good threads on it. Even your new egt's could prematurely fail and the solder fix might keep you going.

I take it you've done the oil/coolant pipe? Known as Bufkin...

Cam seals and valve cover are notorious for small leaks, off and on, all the time it seems.

Thanks for you input lswing. I also thought the pads weren't too badly worn. They were brittle when I pried them off the the metal tensioner "shoes." 3 of 4 of them broke. The new ones are stiff, but more pliable. I'm glad to get them replaced as a preventative item before giving them a chance to fail at 75 mph sometime down the road.

A short few years ago I resoldered the EGT when it failed. It resolved for a while, but then failed again. I bought the set from Audi, of course for Audi $$$.

Yes, I switched to the Bufkin when I had the engine out previously in 2012.