I am still not sure I understand which joint is giving you trouble. I would refer to the bearing cap as the top cover on the housing. On the thrust end, there could also be an end cover which may have originally had a gasket. I assume that the sleeve bearing is pressure lubricated with a circulating oil system. If this is the configuration, as noted above, the point where those two gaskets cross at a right angle is really tough to seal.
First, I have very rarely ever seen a bearing cap that used a gasket like this. All of ours that I can think of have a metal-to-metal joint that is sealed with some sort of sealer (RTV, Permatex, etc.). The end covers usually have gaskets. Sometimes these gaskets also serve as the shim to adjust the end float in the Kingsbury-type thrust bearing. We generally eliminate this gasket by machining the appropriate amount off of the nose of the cover.
We have a few compressors that tend to have chronic leaks coming along the bolts on the bearing housing top cap. In all cases, it is because the split-line is pressurized by the lubrication system. The oil is fed into the lower half housing but pressurizes an annulus that passes all the way around the radial bearing. Where that pressurized annulus crosses the split line, it is very difficult to seal. The oil eventually works its way into the split line and the first path it finds is often a bolt hole. But, our solution does not work with a gasketed joint. We have a very meticulous procedure for sealing the joint. We clean it and prime it with Acetone primer. Then we seal it with two-part catalyst activated RTV. A single oily thumb print on either surface will provide a leak path and the leak will come back.
I have seen one other instances of a chronic leak along a bolt hole that was a result of machining error / casting defect. The bottom of one bolt hole was breaking through by way of a casting inclusion into a pressurized oil galley that feeds the radial and thrust bearings. This would be believable for a single bolt. But it is unlikely if all four bolts are leaking.
If this is the case of two gaskets crossing at right angles, then you may have fewer options. You probably can’t eliminate the gasket since that sets the crush on the bearing. This also makes it difficult to change the gasket thickness. The only suggestion I would have then is to use a very precise procedure for cutting the horizontal gasket. Leave the gasket long and only make the final trim after the top cover is installed and torqued. Trim it off with a razor blade and apply a sealant (two-part RTVwould be a good choice) to the gasket on the end cover. Even if your procedures calls for these gaskets to be installed dry, a thin film of non-hardening sealant may give you the edge you need to avoid the leak.
Johnny Pellin
