As the title says, What are you guys' thoughts on using copper spray on a new Cometic HG?

I've never used it before, but am considering it currently as I'll be rebuilding my engine soon due to a few issues:
1) I replaced the valve seals tonight with the head installed, and when I put air (80psi) to cyl 4 it slowly starting burping coolant out the overflow. I re-torqued the head (ARP studs), and the leakage to the coolant dropped to about 1/3 of what it was, but it definitely still slowly leaks. currently has a Cometic HG installed.
2) cyl 1 has low compression (100psi) and is sipping oil (cyls 2 3 and 4 are at 150psi), leakdown shows its all going past the rings. I'm assuming a ring or ringland is cracked. (custom JE forged pistons, Sealed Power rings)

the engine has never overheated, and there's zero signs of detonation. both the head and block were decked to well beyond the smoothness required for a Cometic HG. I've never lost any coolant before, but about a week ago I did start smelling coolant on rare random occasions for a split second. Never even assumed the HG could be leaking until tonight when I had the compressor in the spark plug hole to hold the valves shut. I basically just want to not worry about this happening again down the road, so am considering the copper spray.

 

also to add to the question above; Hylomar spray?

 

I use copper spray on all my gaskets it doesn't hurt.... also get rid of cometic .... Ive had zero issues running OEM and JE pro Seal

 

Cometic is my only option. It's for my 1990 prelude b20a/b21a1, which typically uses a composite gasket, not MLS.

 

Ok i see .. what about OEM? anyways if i was you id copper spray your new gasket ... and id also take the head to a machine shop have it checked and resurfaced for piece of mind...

 

I run Copper spray on all my HG. I would only put enough on there to make one good coat . Do not over do it and you should be fine. The copper spray helps fill in any variations that the hg cant seal.

 

Never cooper spray any of the engine that i worked on.All of these is allmotor also!

When the cylinder head and block deck are straight i dont see why you need to spray your gasket.

 

OEM is composite. Definitely will be having the machine shop check it out, I'll be bringing it for some valve seat work so I'll make sure they take a look at the straightness and call me before shaving. I've already shaved the head to where it just started touching the factory depth indicators (not sure if any other honda engines have these, but mine does so you know when you're shaved to the service limit) to raise compression to where I wanted it, so from here on out I'll be super picky about when or how much it gets shaved again.

good to know, thank you

I used to think this too, until I started realizing how much the head and block flex and stretch from the high torque specs of a fully built motor (75-80ft/lbs with arp head studs in my engine, stock head bolt spec is 49). I've seen plenty of times when MLS headgaskets didn't seal even when both surfaces were freshly shaved. some right away, some after a few weeks, some a year later (mine)

 

Ive never used copper spray myself, but I know a lot of more experienced builders believe it in...
I kinda agree with flesh199. If the surfaces are straight, and the gasket is ok, I don't think copper spray is going to make a difference.

I have replaced dozens and dozens of HG in my career and never once have I seen the manufacturer specify copper spray. From 100 hp Hondas to 500 hp Porsches.

Copper is a fairly soft element anyways, isn't it? I think detonation is the probably one of the main causes for HG failure in most cases. The pressure spike increase from normal combustion to detonation is sure to blow out the weakest link, and I think the HG is it, unless your pistons are cast, then they might crack ringlands first..

 

Cometic says no copper spray. They do recommend hylomar spray on their head gaskets.

With the viton rubber coated mls gaskets, copper spray actually breaks down that rubber coating on the block side where it's exposed to the coolant.

I found this when pulling the head off my wife's car where copper spray had been used on the 4 layer MLS oem leak gasket for the D15B non vtec motors.

The rubber was all blistered and pealing off into the collant passages. Yet the one that used the permatex high tack spray (a vinyl coating in red) the gasket was perfect.

Copper spray was an old skool trick for the all metal (no rubber coating) head gaskets.

Being you are using a cometic gasket, I would follow their recommendation and use the hylomar spray. They know their materials better than any of us.

 

Curious what you'd recommend for someone using a Cometic headgasket on a stepped deck. For instance, Golden Eagle recommends using copper spray. And, as you stated, Cometic says copper spray shouldn't be used.

 

Actually looking directly at Cometic.... They don't even recommend the Hylomar spray.

http://www.cometic.com/technical.aspx

I got that from someone else when I was researching head gaskets and copper spray.

Also by the looks of the technical page of Cometic, they don't recommend their gaskets be used on a stepped deck/o-ring setups.

Really can't help you there.

 

No, you definitely helped. I was about a week away from ordering one and sealing up my build.

 

We are talking vast majority of these engines being open deck. I'm sure everyone is tracking but step decking increases the clamping force or load closest to the bore. Now step decking compared to bore height and outside edges is like .0003" with a closed deck I could see if there was so much of a minimal variance it could tarnish the seal and premature hg failure. But dealing with an open deck it's a much smaller area.

I'm not bragging "knock in wood" but I torqued down my genuine OEM Honda hg twice while while finnicking around mostly because it was my first build lol but point being I had open deck, step decked bottom and resurfaced head. 10000mles later in june will be a yr and still have 250 across the board.

I see alot of pple have hg problems. Tips n hints
Calibrate torque wrench for accuracy, use recommended lube, research how to tighten them ie. If you feel a slip back off and re-torque, prep, prep, prep lil bit of denatured alcohol on clothe and wipe down both surfaces no coolant or oil contaminants.

 

I've always used copper spray just on my MLS gaskets. Cant hurt anything.

 

i remember reading something about the cometic gaskets blowing out. the issue wasnt in the materials but in the manufacturing process there would be small bits of metal and material that would get between the layers in the gasket. the place i read that recommended taking the gasket apart and cleaning each layer's surface. i just blow it out real good with compressed air. ive used a few cometics, the first time before i blew out the gasket i feel i had a bit of an issue. since then no issues related to the gasket.

also are you going back and checking the tq after a few heat cycles on the headstuds?

 

Yes I always check head stud torque after a few heat cycles.
I ended up just getting a new gasket. actually, I had a brand new one in storage that I'd completely forgotten about lol. it was thinner than what I needed though, so I just cut the rivets off the old and new gasket, and used one uncoated layer from the old gasket, sprayed it with copper, washed all the layers of the new gasket, and added the copper sprayed old layer to the middle of the new gasket for correct thickness. zero issues so far including a few intense dyno sessions. I'll be pulling the head again in a year or so after I finish building an entirely new head design I've planned out, so I can check for any effects of the copper at that time if no issues arise before then

 

What proof do you have to substantiate this opinion?

I have evidence that contradicts this beyond just manufacturer recommendations.

 

From my experience building engines and consultation of some people I would consider experts.

For MLS gaskets (not composite cometic)?

 

I just copper sprayed my HG on my engine. Ill let you guys know how it goes. This is the 4th time doing so with no issues. Last time around seen 30psi boost. No oring just a step deck block. This time will be much higher in Psi.

 

You guys might find this interesting. I don't trust "experts" as that usually means an old timer who's highly experienced but may not know what the old habits do with current day materials not utilized back in the day that the old habit was started, and originally found to be successful.

Two OEM MLS head gaskets from the same model engine, both with the current day viton rubber coating in black. Both gaskets were pulled from running motors. The copper spray one was just starting to run rough and partly why the head swap and new MLS gasket installed without copper spray.

Anyways, you can see the viton rubber seriously compromised by the copper spray causing bubbling over the water jacket. Only a matter of time before the deterioration moved beyond the jacket:



This next pic is the OEM MLS gasket with black viton rubber coating that didn't have copper spray on it that I pulled from my personal running motor (same engine as the other). There was and is no blistering. I had stored the head gasket in with the head and traipsed it around a bit so the head scraped a little viton material off. When I pulled it off the motor the head gasket was in perfect condition.



This coupled with head gasket manufacturers stating that copper spray is not recommended on their viton coated MLS gaskets tells me the old school Copper Spray is not the method for current day viton coated head gaskets.

On the old V8 flathead that has an all metal uncoated head gasket, copper spray is a must. On our Honda's with their viton coated gaskets.... Not so much.

Here is a fuller picture of the Copper Sprayed Gasket and you can see the large patches that fell off into the coolant:



Also, the pictures of the Copper Sprayed gasket was immediately after I pulled the gasket off the block when working on my wife's car. I was so surprised at the blistering I immediately grabbed my phone to take those pics. That gasket wasn't stored or transported at all prior to photographing.

 

Interesting.

Well I just swapped heads on my motor last year. Previously copper sprayed gasket. Went 3 years with E85, 30lbs of boost, many miles, 600whp. Looked totally fine

GE 84mm Gasket. Replaced it with the same thing.

I dont have a pic of the gasket after

 

Also, it looks like the copper spray only affected the area around the cylinder. if the spray was truly the cause of that failure, why would it only be concentrated there?

 

A photo of bubbling gasket coating does nothing to prove that it's caused by copper spray. Viton, or fluorocarbon is highly chemical resistant. But in that environment there are so many variables it's impossible to conclude that caused the deterioration. Could have been a bad batch of antifreeze, other chemical reactions, bad factory bonding etc.

 

Definitely a fair point. Thank you.