Head to Cylinder Seal?

[Handyjay]

On my recent 930 rebuild the reputable machine shop I use told me to use brush on Copper Coat on the mating surface between the head and the cylinder. Now that I have the engine apart again for a broken stud and cleaning up the remains of the Copper Coat I wonder how effective this is. What are others doing that have not fly cut and installed gasket seals? Thanks for any and all suggestions.

[KTL]

Head to cyl is typically dry. Can you shoot some pictures of how the surface looks with the copper coat? I'd be interested to see it since the coat will provide a "footprint" of how the head and cyl were behaving with each other. Since most are installed dry, the pics we see aren't as revealing when talking about suitable clamp job done by all steel or all dilivar head studs.

Thanks,
Kevin

[Handyjay]

Unfortunately I have all the remains of the Copper Coat cleaned up. Actually the visible residue was outside of the mating surfaces of the cyl and head. You could not see anything on either the surface of the head or cylinder. I cleaned these surfaces with carb cleaner and just wiped off a black film. The rest of the Copper Coat I had to carefully scrape off.

[AlfonsoR]

I've used the spray-on copper spray for the head gasket on my water cooled in-line 6 engine. I follwed the advise of a proffesional BMW mechanic whom highly recommended it. He said it improves sealing performance. However, I am not sure i would use it on an air ooled engine. My thinking is that stuff moves around a lot more and putting sticky stuff will inhibit some of the normal movement?

[KTL]

I used the copper stuff on cam sealing gaskets (seals the cam cover plate to the cam housing) to prevent weeping and recently ended up with a strong drip leak due to shifting of the gasket. I don't blame the sealant, as that's a touchy gasket installation.

Point being is I think it's good for sealing gaskets. But I wouldn't use it in place/substitute of a gasket.

[Henry Schmidt]

Over the years we've found the best sealing method is a stable head stud.
If you have a broken stud, you are probably still using Dilivar studs and they offer perhaps the poorest results when the goal is cylinder to head stability.
Supertec Head studs offer the best stability with a plethora of other studs offering differing results.
This is our experience. Other may have differing experiences. Few if any who have used our stud system have any complaints. In fact zero complaints have been referred to me.
As for your question about "sealing compounds", I would suggest that a stable junction would not benefit from a sealing compound such as Cooper Coat.