Which sealant do I want

[marciaanddave]

We own a whitby 42. The center diesel tank is in the keel and is made of steel. The “lid” is aluminum and bolts to the top. The joint between the two is subject to both salt and fresh water, and has failed.

My intention is to remove the “lid”, clean and reasonable. Which product should I use? We are currently in Key West.

[SVTatia]

Originally Posted by marciaanddave

We own a whitby 42. The center diesel tank is in the keel and is made of steel. The “lid” is aluminum and bolts to the top. The joint between the two is subject to both salt and fresh water, and has failed.

My intention is to remove the “lid”, clean and reasonable. Which product should I use? We are currently in Key West.

Please let us know what do you mean by "joint" is this a gasket?
Is the AL "lid" in good condition or the steel beneath is compromised?

[marciaanddave]

I have not disassembled the yet so I don’t know if there is a gasket. I believe the metals are in good shape but will only be able to confirm that after disassembly. I want to have the materials on hand prior to that. I assume 3M makes something that is compatible with diesel.

[steve77]

I wanted to be able to remove the inspection port on our fuel tanks, so I made new gaskets from rubber, about 1/16" thick. There may be sealants that will work, but I wanted the simplicity of a removable gasket.

If you decide to go this route, be sure and find some way to mark the gasket so you know the orientation to reinstall it.

Cheers!

Steve

[Pauls]

Buying bulk O-ring material, Buna N, cutting it to length and using the correct glue to glue the ends together makes an extremely reliable sealer. Buna N is the standard fuel resistant rubber for this sort of thing. The o-ring shape sees a high clamping force from the clamping bolts due to the small cross section (compared to a flat gasket). The o-ring must be located inside the clamping bolts, otherwise you will leak at the bolt locations.

This approach is very high reliability. It is easy to do and is easy to remove and replace. I would not attempt to reuse these - make a new one each time the top is removed.