[C320-list] Tightening don onto rubber gaskets?

[Graeme Clark]

I've installed a new fuel sender unit and added some fuel tank inspection ports. I have used 1mm gasket material for the ports (Viton material) and the sender unit had a 2mm gasket supplied.

I have also used hylomar non-setting gasket sealant.

Not having looked too closely at the old gasket when i removed the broken sender, I was surprised to find the extent to which the gasket material compresses and squeezes out to a diameter greater than the plate. I dont want to over tighten the screws (on a test piece when I did a destructive test the screws (stainless) sheared before the threads (aluminium) stripped, to my surprise).

On the other hand I dont want to leave any possibility for leaks.

can anyone give guidance on how tight i should be doing up these bolts - (no 10 self tapping flanged hex headed) either in terms of torque or in terms of how much gasket squish!

Cheers

Graeme
‘Jakar’, 1996, Hull 366.