Leak Fixing Question...

So I've been making some progress chasing down a leak (or two) on my O-360...I'm at the point where I think I know the leak is coming from and I'll be able to confirm it in the next day or so.

I think - I don't know for sure yet but I think - the worst leak is coming from the three rear sump bolts (under/nearest the oil screen/#3 cylinder.)

Naturally, I need to check these for correct torque. The previous owner seems to have added some RTV around there in the past, but I haven't confirmed that that RTV was to fix this leak. Seems like it might be, but I don't know.

If it turns out that it's the sump bolts, and the torque is right...what's my best course of action? More torque?

I am not excited about the idea of disassembling everything under the motor to get to the sump, pulling it, and re-sealing everything, but I'll do that if that's the only way. I'm just wondering if there are other options.

While the best course would be to pull the pan and replace the gasket, I have a method that has worked for small leaks. Not a great fix, but can stem the tide until the proper repair can be done.

First, determine the length of the flange area that is leaking. Clean this aggressively with a strong solvent. It will take many attempts, as the oil will keep wicking out of the flange. Very quickly after the last cleaning, apply permatex "the right stuff" to the outer area of the flange, covering the top and botom flanges.

The right stuff has a strong adhesion component unlike most sealants. It is a pain to remove because of that, but it is what makes it a good tool for this type of job. I did this on a leaking front engine cover on my son's buick. It was losing a gallon of coolant per hour and this fix got him home on a 7 hour drive without losing a drop. Terrible mess to clean up when I pulled the cover, but it worked well and served it purpose.

Larry

lr172 said:

While the best course would be to pull the pan and replace the gasket, I have a method that has worked for small leaks. Not a great fix, but can stem the tide until the proper repair can be done.

First, determine the length of the flange area that is leaking. Clean this aggressively with a strong solvent. It will take many attempts, as the oil will keep wicking out of the flange. Very quickly after the last cleaning, apply permatex "the right stuff" to the outer area of the flange, covering the top and botom flanges.

The right stuff has a strong adhesion component unlike most sealants. It is a pain to remove because of that, but it is what makes it a good tool for this type of job.

Larry

Click to expand...

I used the term RTV generically....I'm wondering if that's what the stuff was - it's red-orange in color.

I will take a look.

bill.hutchison said:

I used the term RTV generically....I'm wondering if that's what the stuff was - it's red-orange in color.

I will take a look.

Click to expand...

The Right Stuff is NOT RTV or at least not typical silicone RTV. It is black in color. It is more like construction adhesive than RTV. I would not expect any RTV sealant to work very long in this type of fix.

dumb question

Would Proseal work if clean?

I chased a handful of small leaks around the engine for about a year ... I didn't have to do anything but replace star washers and make sure the torque was set correctly.

bkervaski said:

I chased a handful of small leaks around the engine for about a year ... I didn't have to do anything but replace star washers and make sure the torque was set correctly.

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Curious about both your process and what you found. This seems to be a common problem for a lot of owners. Love to know anything that might help me out.

Also a follow up question...

If I had to pull the sump on a carbureted O-360 RV-6A, would I have to remove the nose gear to do that or would I just be able to remove the airbox, carburetor and associated angle/linkage?

bill.hutchison said:

Also a follow up question...

If I had to pull the sump on a carbureted O-360 RV-6A, would I have to remove the nose gear to do that or would I just be able to remove the airbox, carburetor and associated angle/linkage?

Click to expand...

I have never done it or considered it, but probably no issue. Assuming you have a more modern sump that uses the oil pickup intregal to the sump casting, there is nothing sticking out more than an inch below the parting line of the case/sump. You can remove the nuts / bolts and slide the sump forward after dropping an inch to 1.5 inches to get the studs in the sump clear of the case. If you have an older engine that has the pickup tube bolted to the case, you probably won't get it off with the nose leg in place, though never studied the geometry of that.

If I remember correctly, all of the sump studs are in the front, so you can tip the front down some without having to drop the rear of the sump much before sliding it forward.

Larry