Oil leaks and engines seem to have a symbiotic relationship. The oil leaks provide the engine a chance to vent its frustration at being abused, while the engine allows the oil to escape and spread itself out in the world at large (or at least in your bilge).

Most of the time these leaks are tiny, and difficult to stop. Some years ago we had such a situation on Beowulf. It wasn’t until we ran into a diesel mechanic in Maine that we learned how to deal with these small leaks.

The first step is to identify the leak’s location. As long as the engine is kept clean, you can find the leak without too much difficulty. Once you know its location, the next step is to clean the area with a good detergent.

With the general area clean (better yet, clean the entire engine and its surrounding area) use a little “Brake Cleaner” – which comes in an aerosol can to really degrease the leak area. Make sure your work area is well ventilated, as this is noxious stuff. And keep it off nice finishes, as it is hard on paint and fabric.

There are a variety of sealants which can be used. We like RTF silicone, which works well in high temperature environments, and about which we’ve written in the past. However, just running a finger of the RTF around the leak won’t do much good. That oil is under pressure and it will just push the RTF bead away.

However, if you pull a vacuum on the block, as Linda is doing in the photo above, you can suck the sealant into the crack.

You need some form of vacuum cleaner for this – a small portable will work well. Make a seal with your hand and rags between the vacuum inlet and the valve cover. This puts the entire block under vacuum. While the vacuum is in place, run the bead of RTF over the leak. Leave the vacuum in place for five to ten minutes. If you’re lucky, the leak will be gone.