Watertightness on the dome nuts - Curious

Hello all,

Just curious.

As I am about to fit and torque the large chrome dome nuts.

What keeps water from sipping up through the large washers or the dome nuts?

Am I supposed to smear some sealant around there?


They are sealed by the head gasket. On initial start up, you may get a slight escape up some of the studs. Don’t worry it soon stops as the heat is dissipated. Re torque head after 24 hours.

I don’t see how the c/head gasket helps at all. The studs go all the way down into the water channel and the gasket does not even touch the studs stems…

G’day Eric,

I rebuilt an XK engine years ago and wondered the same thing so I oilstoned the base of the dome nuts and both sides of the washers before I fitted the head and from memory a smear of gasket sealant.


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Hi Eric

it will seal around the head washer to head face. I agree this is not ideal, as it means there is water between the stud and the head. But its the way they are! I coat the stud in “neverseeze” to help limit the effects of corrosion.


The head gasket does nothing. Oil stone or fine sandpaper on glass to get a good surface is a good idea and coat the studs in antiseize.
A thin smear of sealant, only if you want. A few little leaks at the beginning can happen sometimes but they will normally seal up on their own according to my experience and ‚research‘ here on the forum back when I did my head gasket.
Nothing to worry about.


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This has been my experience as well after a head service a few years ago. If the car runs for an extended period during our summer I have one that weeps a little. All rather normal for long stud engines. Paul.

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On long stud engines, I would use a fillet of RTV, around each stud, as it exited the block.

That way, the RTV sealed off the space twixt the stud and the head.

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I like a good fillet- medium rare :wink:

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