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Gasket for Distributor Cap

T

tgmmartin

New member
I’m tuning up a new to me GM MCM140 (3.0) inboard. Circa 1986 with what appears to be the ordinal distributor (I would suspect cap isn’t original).

Changing the rotor and points today I noticed that the old cap appears to have the remnants of an old rubber seal/gasket. For the life of me I can’t find any reference to such a part in any parts lists or diagrams.

Was this a rubber gasket? Or am I overthinking this? Maybe just grommets around the screws?

I am going to replace the cap and would like to ensure that I use a gasket if it was designed for one.

Thanks
 

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I have a Prestolite points distributor on my '88 OMC 4.3 V6 and the caps always come with gaskets.
 
If there was ever one they dont seem to offer/show it in the parts diagrams. If a new OEM cap is purchased it may have one attached to the cap but if not there is no need to be concerned.

That cap design keeps the insides very protected.

I serviced many hundreds of those and cannot honestly remember any gaskets for that point distributor cap.
 
kghost said:
If there was ever one they dont seem to offer/show it in the parts diagrams. If a new OEM cap is purchased it may have one attached to the cap but if not there is no need to be concerned.

That cap design keeps the insides very protected.

I serviced many hundreds of those and cannot honestly remember any gaskets for that point distributor cap.
Click to expand...

Ayuh,..... Ditto,...... Never seen a cap gasket,.... not needed,.....
 
Both the ones I got from BRP and the Sierra aftermarket ones I use now, have had them...not shown in any parts diagram, but the caps always come with them. The gaskets have some adhesive on them and stick on to the cap, so you can remove the cap without tearing up the gasket. Not sure if its needed, I think it depends on how humid your boating/storage environment is.
If you get a new cap and it has it, use it if not I wouldn't worry about it...
 
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louc said:
Both the ones I got from BRP and the Sierra aftermarket ones I use now, have had them...not shown in any parts diagram, but the caps always come with them. The gaskets have some adhesive on them and stick on to the cap, so you can remove the cap without tearing up the gasket. Not sure if its needed, I think it depends on how humid your boating/storage environment is.
If you get a new cap and it has it, use it if not I wouldn't worry about it...
Click to expand...

If you are referring to your V6 then that may be true.

But for the '70's and '80's Mercruiser 4 cyl it is not the case unless some aftermarket sellers do so. If you look close at the cap there is not much if any room for a gasket.

In the end its not needed for that model Mercruiser cap/ign.

The Mercruiser V6 and V8 Thunderbolt caps all came with gaskets (OEM)
 
Thanks everone, thats the sort of insight that I needed.

Will order the new cap and if it has a gasket then it will be used, if not then I won't stress it.
 
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