68 327/350 oil leak

[Richard D.]

This weekend I noticed an oil leak on my car.

I thought it was a rear main seal, but then I discovered that directly over the oil filter mounting flange on the block, a "patch" of what looks like JB weld epoxy, and weeping from beneath that patch, oil coming out.

Now, I had never noticed this patch before, and I'm hoping that it's not a crack in the block!

Ques. - Since I noticed some threaded bolt holes in that area of the block (just above the mouning flange for the oil filter), I'm hoping that there's a threaded hole into the oil gallery area for a sending unit or something that the previous owner buggered up, and slapped some of this epoxy on to stop the leak. Does anyone know if there is a threaded hole into the oil area in this location?

Secondly, if it is a crack, what type of repair would you recommend - welding?

I intend to have the engine pulled, and the epoxy ground off to figure out exactly what's going on here, but I thought I'd ask.

It is the original motor, with a recent rebuild (about 1,000 or so total miles since the rebuild), so I will do what I need to do to save it within reason.

Thanks in advance for any advice.

Regards,

Rich

[Joe L.]

Re: 68 327/350 oil leak

Richard-----

In the area directly over the oil filter boss on your block are 2 threaded holes. One of the holes is for the clutch cross shaft inner ball stud. This hole is "dry" and does not go through to anywhere but cast iron.

The second hole is roughly between the oil filter boss and the ball stud boss and tapping. This hole is taped for a 1/4" NPT pipe plug. Usually, an indented square-headed pipe plug is installed in this hole. This hole DOES go through to the oil gallery and pressurized oil will be found here. This plug usually gives no problem and is not generally removed even when the engine is rebuilt.

This could be where your engine is leaking oil from. If it was leaking and someone decided to use an external application of JB Weld to cure it, that would be a VERY temporary fix. JB Weld is great stuff, but it's not going to seal in this sort of application. Your best bet is going to be to remove the epoxy and the plug and check out the threads in the block. If necessary, these can be repaired with a special Heli-Coil insert for pipe thread or the hole can be re-drilled and tapped for the next larger size pipe plug.

If you do have a crack in the block, I DO NOT recommend repair by welding. To have any chance of success, at all, welding needs to be done in a very specialized way and using ovens for precise heating and cool down. I still wouldn't do it unless there was no other way. Pinning is the safest and best repair method for most cast iron block and head repairs. In this method, special tappered, threaded pins are used for the repair. The crack line is drilled and tapped at one end and a pin installed. Then, an overlapping hole is drilled and tapped, partially in the first pin and partially along the crack line. This process is repeated until the entire crack is "removed". This is a job for someone who has great experience and skill in doing it. It's also quite expensive because a lot of time is involved.

[Richard D.]

Re: 68 327/350 oil leak

Joe, once again, thanks for your input on this (and giving me some hope!).

I'm led to believe it's the pipe plug hole that for one reason or another is messed up since all else on the motor is really good, and was done well on the rebuild.

I'll know for sure when the motor is pulled, and the epoxy removed.

Regards,

Rich