'29 Standard-Six mystery oil leak

[W_Higgins]

I'm working on the above mentioned Buick and have an oil leak I can't pinpoint. It's coming from the right-rear of the block running down next to the starter. It must favor the right side because it doesn't run down the left at all:

I've removed the oil lines to-and-from the oil filter, including the whole line that runs behind the block, and looked for cracks. Everything looks perfect. Is this most likely the gasket where the cylinders meet the crankcase? It's just impossible to see back there. Sitting here running at a fast idle won't do it -- I have to take it down the road and it's a pretty substantial leak.

By the way, I just replaced the valve and side cover gaskets, so that's not the source.

[Mark Shaw]

All I can suggest is to first use some good engine cleaner to remove the old oil before looking for the leak. I believe some shops use an additive that shows up in black light so they can trace leaks.

You may have a cracked head near the oil channel that feeds the rocker assy.

[W_Higgins]

Yeah, I already degreased everything before looking as it was already such a mess. All I get is oil emerging from somewhere I can't see and running down the side of the block by the starter. I'm going to ask around and see if someone has a fiber optic camera I can borrow.

Are these heads known to crack in that location?

[unimogjohn]

Walter, I have had the brass fittings from the oil filter line crack with age. You might want to check. They are hairline so you really have to clean and then inspect as suggested. The blocks usually do not split, or I have never heard of one doing that. How is your valve cover gasket?

[W_Higgins]

That's a good suggestion. I'll take a more critical look. In particular, I removed the pressure line that runs from the left side of the engine, around the back, and has a special fitting block held on with two bolts hoping that was it, but I pressurized it and it's not leaking.

The other thing that bothers me about it is I can clean it off and run it at a fast idle with 40 psi oil pressure and it won't do it. If I take it down the road and get out and check, that's when it's coming out. That makes me think it's the gasket where the cylinders attach since pressure alone isn't enough -- it's like it needs to be slinging it around vigorously.

The valve and side cover gaskets are new -- partly hoping that would cure it and partly just because it was time.