Good point re film thickness, I've used 518 on intakes like ford Cleveland with the metal pan gasket and removed them and it squeezes out to pretty much nothing but thats a thin flange point. Head gasket area could be a different story! Like when i have removed copper gaskets that someone has used 3bond on, you can scrape a thin layer of 3 bond from almost everywhere apart from around where the head bolt goes thru, it definitely leaves a thin layer , not good.mk e wrote: ↑Mon Oct 22, 2018 3:20 pmI've not tried 518 on a head gasket....I've been scared about the film thickness. The aviation sealer torques out really thin but 518....a few thou is about as thin as it gets I think. I use it on just about everything else and have been using it since the mid 90s....everything I've ever torn apart has looked good.....it does get a little brown where it was hot but still seemed to be flexible and sealed.cjperformance wrote: ↑Mon Oct 22, 2018 3:10 pm
Mark, yes correct on the aviation over the long time span, it does eventually degrade and turn to that dusty crust for sure.
I've never tried 518 on a head gasket, that said I'm sure it would be perfectly its very good stuff.
I wonder how that will go long term, 10/15 years?
I'll keep the 518 for experimenting on a personal copper gasket 1st !