Good Sump Joints

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I was stripping down an engine the other day, not one that I had rebuilt in the past; and found the sump gasket heavily glued into place with that red, hard gasket compound. It was almost doing its job but not quite as oil was leaking from the joint. It was the very devil to get the sump off but in the end persistence and gentle persuasion won the day.

Once off and cleaned up, I wrapped some aluminium oxide paper around a flat plate of steel and rubbed gently over the mating face of the sump pan. As shown in the picture, the metal around the bolt holes was cleaned and polished but the abrasive paper did little to the areas between the bolt holes. This sump would never seal properly if left like this!

sump 4 First I checked the little turned up lip around the edge of the sump pan and found it was also bent and distorted. The first thing to do to remedy the situation is to gently persuade this lip back into shape. I use the jaws of a ‘joddler’ (if you know what that is), if you don’t have one then use a pair of mole grips or heavy duty pliers.

Mole grips are best as you can lock the jaws on and gently bend the lip back into place. If a section of the lip is bent then make sure you work along the whole length bending it a little at a time, moving the jaws each time. You may have to repeat the process several times before the section is straight.

Now you need an upright steel bar in the vice which fits between the lip and the side of the sump pan, you will use this as a mandrel. With a clean hammer gently, very gently, dress the mating face of the pan until it is virtually flat, make sure the area around the bolt holes is no longer raised in relation to the rest of the face. In fact if they are slightly depressed then the bolts will pull the joint flatter and tighter.

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Always use a non-hardening gasket solution and the proper paper gasket, take care with the bolts as they are very easy to shear off, a little at a time and work your way all around the joint is the best way to fasten them.

This article, written by Malcolm Watts, originally appeared in CA7C Seven Focus in Feb 2007 p23.