Cutting rubber gaskets

[JHZR2]

On my Bosch IP job, the front cover gasket hasn’t leaked, but I wanted to re-seal it.

There are two covers, aluminum and steel. And two gaskets as a result. The steel cover gasket is NLA from Mercedes.

There is a visible difference.

There’s also hardly any sealing area. So the thin one intended for the aluminum cover might be “good enough”. But I assume it rides in a milled groove in an aluminum cover, and it will shift out of place on the steel one.

For now I put some of this on the surface:

And put the old gasket back on, screws torqued to 10 in-lb.

So I’m thinking I probably want to consider cutting my own. But what’s the right way to do it by hand. I used to make seals for fuel cell stacks, but we had fixtures with razor sharp hole cutting tools. Which I don’t have, but maybe need to get? Or is there a better way to punch holes into rubber stock? I know I can get sheet rubber at McMaster and just need to find the right one. Most of it is razors and straight edges.

Anything else I need to know?

 

[Trav]

As long as that gasket fits I would just put it on the cover (not both sides) with a very thin coat weatherstrip cement to hold it then install, it will hold. We used to put old rubber valve cover gaskets on that way, no problems.

 

[JHZR2]

As long as that gasket fits I would just put it on the cover (not both sides) with a very thin coat weatherstrip cement to hold it then install, it will hold. We used to put old rubber valve cover gaskets on that way, no problems.

Maybe that’s why they discontinued the fat one?

Can I use that permatex stuff? It’s non hardening. Or do we want something with more “stick”?

 

[Trav]

Something with more "stick" apply it, let it tack and mount the cover right away and tighten lightly. Leave it a couple of hours then torque to spec or snug and a bit.

 

[Jump1]

On my Bosch IP job, the front cover gasket hasn’t leaked, but I wanted to re-seal it.

There are two covers, aluminum and steel. And two gaskets as a result. The steel cover gasket is NLA from Mercedes.

There is a visible difference.

View attachment 154232

There’s also hardly any sealing area. So the thin one intended for the aluminum cover might be “good enough”. But I assume it rides in a milled groove in an aluminum cover, and it will shift out of place on the steel one.

View attachment 154233
For now I put some of this on the surface:

View attachment 154238

And put the old gasket back on, screws torqued to 10 in-lb.

So I’m thinking I probably want to consider cutting my own. But what’s the right way to do it by hand. I used to make seals for fuel cell stacks, but we had fixtures with razor sharp hole cutting tools. Which I don’t have, but maybe need to get? Or is there a better way to punch holes into rubber stock? I know I can get sheet rubber at McMaster and just need to find the right one. Most of it is razors and straight edges.

Anything else I need to know?

Google hollow hole punch set. I have a set from harbor freight. It's a kit of different sizes. Place rubber on soft wood like pine and hit punch a few times hard with a hammer. They work well. Razor knife should cut balance.

 

[paulo57509]

Either the Aviation or Hi-Tack should work.

 

[CleanSump]

I've used cartridge cases fo cut bolt holes like the punch sets. Exacto type knives are very controllable for contours.
Leather cutting punches work well for rounded inside edges.