Why not to spray MLS headgaskets: Discuss

[Turbo Monk3y]

For the Past 7 years I have been spraying my MLS or Cometics with the Orange Permatex Copper spray. I have never had a Failure....Ever..... My stock 6bolt shortblock has seen between 25-40psi with no problems. So therefore I shall keep using Permatex. Just make sure your Head and your Deck look like a mirror finish before you put on your Gasket.

 

[JohnTSI]

I have been using Mopar gasket sealant on the HG on both cars and have had more luck with it than without on MLS gaskets.

 

[bryanwheat]

Hey! We're finally in the same thread over here. .

The last three HGs I've used on my 420A were all MLS. The first two were sprayed with copper and did not leak. (First one replaced after cracking a piston and having to take the engine apart. Second one upon installation of ARP head studs due to stockers stretching.) The last time I replaced the gasket, I used a brand new MLS, treated it like a gem from the moment I bought it, and did not unwrap it until the minute I was ready to install it. I had heard some people saying that there was no need to spray an MLS, so I figured I would give that a shot. It started leaking within a month.

So, I dunno. I guess, if I was working on one of those new, World Engines or risked not getting paid if I submitted a HG warranty issue that had been sprayed, I wouldn't spray them, but my personal experience will have me spraying them, albeit with an intentionally lighter coat, from now on. Maybe just on the block side to find a sort of compromise.

I can see both sides of the issue. In a perfect world, with a perfect mill, eight of the nine planets aligned when the sun is in Mercury and a Blue Jay whistling Dixie, there should be no need for the spray, but I never seem to work on my car in a perfect world. (If this was a perfect world, I'd be driving my GVR4 today. )

EDIT:
By the way, Kelly. You have 666 posts. Evil.

Did you by chance resurface that head after it was lifted due and stretched the bolts? That is most likely the reason for not sealing, a slightly warped head. Metal head gaskets have to have an almost perfect sealing surface. Don't worry so much about the block, it doesn't warp that easy, but the head. I have installed multiple mls gaskets on 4g63 motors (not a 420a, but same situiation) and the first time i didn't resurface the head, and it did leak, but after that i resurfaces the head and bought arp studs and it they never leaked again, this is also not spraying a drop of copper seal on them. The manifacturer of most mls gaskets reccomends installing them dry. May i also add to anyont thinking about installing a mls gasket without arp head studs should reconsider. The head will definetly stretch the bolts in no time, well in boosted cars anyway. Just wanted to point that out.

 

[darkiller_666]

accidental post

 

[SBR Joe]

Ive used copper spray, and ive used Hylomar. Never have one had any issues with the gaskets. All saw 25+ psi consistantly. Regardless of theories and speculations, personal experiences yielded no ill effects, so i see no reason to think otherwise.


Joe
SBR

 

[slowgsr]

i use permatex copper spray.. 3 coats on both sides of mls gaskets on my stock 4g63. 89ft lbs on the arp head studs and ive never had any issues. car went 11.2 @128 on 27lbs, ive got 31lbs dialed in now and looking for some low 130 traps and 10 sec passes.

 

[pneumo]

FYI the new Felpro mls gasket has a tacky coating already applied to it. I wouldn't spray it since it might not seal as well. Any gasket that's just bare metal might need a coat of copper spray to seal better.