Crankcase bolts

[William Hughes]

I have been chasing oil leaks from around the front of the engine (O540) for the last year. Front oil seal replacement got most of it. New valve cover gaskets took care of quite a bit more. A few loose push rod tubes were snugged up and that also helped. But there was a persistent intermittent irregular seepage that was pestering me and it just seemed like too much. The oil is always trying to get out, but there is a difference between a normal seepage and too much. Hard to describe but you know it when you see it.

Then I read a story (I am sure it was in a digital back issue of the Comanche Flyer) about someone finding loose crankcase bolts during a long cross-country. I was having the aircraft taken in to replace the oil pressure gauge and a third attempt to get a tachometer that would indicate properly, and so I asked them to check the crankcase bolts along the front.

And there it was: three bolts that were finger tight. These were checked, two were replaced, and all the bolts around the crank case torqued to spec. I'll bet those loose bolts had something to do with the front oil seal giving out, and the push rods tubes being loose as well.

Today, there was no oil leakage after a 1.9 hour IFR training flight that included two full power missed approaches. There was a bit of oil visible on the carburetor, but it did not seem to offend my sensibilities.

Another mystery chased down with help from the ICS.

[N3322G]

Always good to hear a happy result ... we are all in this together.