Head gasket , to seal or not to seal?

That is the question ? Would you use permatex or similar , on a payen head gasket ?

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I have never used a sealant on a head gasket, and have never had a need to.

No. But make sure your surfaces are cleaned of any residue. You may need to use a little sealant on the dome nuts and washers, but that is all.

Thanks guys , it was the answer I was expecting . I never have in the past , but heard of someone using it recently .

Only use it if the manufacturer of the head gasket recommends it.



Exactly, I have had a couple of XK engine rebuilds plus s couple of cylinder head rebuilds, always with the ”official” gasket, no sealant, BUT on the MKV the Australian maker of the composite gaskets suggests a thin layer of blue Hylomar on both sides, so that’s what I did. And it was perfect. And came off quite well when I had to take the engine apart for other reasons (broken piston, broken exhaust valve and broken cylinder wall in cyl nr. 4.) so I will mount the next one just like that, although we can not get it in a spray can, only in a tube.


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It was recommended to me by my engine builder to use little pats of ultra black around the water ports, especially if there are any slight irregularities in the surface as there often are. Not even beads, just fingerprints. Also around the front as that area isn’t clamped by big head studs. Assemble wet. I’m generally averse to silicone but there is no downside to doing this.

Interesting thought.
While watching Richard Michael Owen rebuilding his Jag XK engine on Youtube, I was amazed to see him apply a thin bead of liquid silicone on all the mating surfaces…
Having just stripped my XK120 engine and found endless residue of such - I swore I would not follow this tactic, but somehow, there seems to be some justification.
My cyl head is off to Fiennes in Oxfordshire for a rebuild, so I hope when it comes back it will be so clean, shiny and true I might not need anything other than the original equipment and diligence while reassembly.

On a stock steel gasket, the only thing I would use was a good healthy dose of copper coat, and a fillet of RTV around the base of each stud. That kept water from going up into the head, on Long stud engines, and also helps seal off the head on short stud engines.