Crazy or stupid? Oil leak revealed

[BDPetersen]

Two months ago I broke into someone’s thread regarding an oil puddle near the nose wheel. I supplied a photo of my similar dilemma. It was a static leak seeming to come from somewhere in the aft part of the engine. It persisted for the two months with no solid clues or smoking gun except for drips hanging from some of the sump bolts. Time in the Spring gets compressed and my apprehension about diving into the issue served as an anchor as well. The reluctant decision was that pulling the engine was the only way to get access to whatever it was. The only likely culprit seemed to be the sump gasket, but without obvious seepage. So the prep for the procedure was done in between the other projects (airport mowing, etc.). Today the engine was pulled. Hanging on the hoist nose high, the dripping resumed with a vengeance, still with no precise point of leak, just a general ooze. A mystery is how 6 quarts in the sump could still find it’s way through the sump gasket. I would have thought the oil level was lower than that.

Anyway, I will attach a photo. The crazy or stupid part is regarding what to do next. The engine is 2300 since oh. It runs strong but I have no desire (except monetary) to have to pull it again someday. The monetary part is to just put in a new gasket and soldier on. The other part is to send it to the overhaul spa and wait for autumn. One is crazy, one is stupid. Just not sure which is which.

[tgardnerh]

My understanding is that an oil leak is an annoying mess, not an safety issue (within reason).
Presumably you have an airplane to fly, especially in summer, so change the gasket and if it works great, otherwise OH the engine when the weather goes downhill (if you are so inclined).


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[BDPetersen]

A great scenario save the fact that the engine removal is an unpleasant task I really don’t want to repeat. But I’m considering that course of action. Thanks 

[carusoam]

See if @M20Doc has insight on changing out the oil sump seal….

Best regards,

-a-

[BDPetersen]

Thanks. Certainly a simpler, less expensive way to go. But worry having gone this far it might be a band aid on a 2300 hour engine. I’ll probably throw an oil analysis and filter inspection into the decision.

[carusoam]

13 minutes ago, BDPetersen said:

Thanks. Certainly a simpler, less expensive way to go. But worry having gone this far it might be a band aid on a 2300 hour engine. I’ll probably throw an oil analysis and filter inspection into the decision.

Plan both…

OH times are getting really long lately….

Soooo… a band aid today…. May get you to OH at a nicely scheduled time in the future….

This gives you some time to think about the various options…. OH, factory reman, brand new….. 

Some forever planes get amazing engines….    

Best regards,

-a-

[BDPetersen]

At my age forever is not that long. LOL

[Guest]

The sump gasket isn’t really hard to remove.  Remove the exhaust system and intake pipes, remove the bolts holding the sump to the case and drop the sump, clean up the gaskets surfaces and reassemble using new lock washers throughout and use a torque wrench.

Clarence

[hammdo]

You could bore scope while doing the gasket to see what the cylinders look like. While sumps off, can inspect to see if anything is at the bottom of sump. If she's strong and performing well, could have many hours left in her. Fix the leak and fly it like M20Doc suggested...

-Don

[BDPetersen]

Pull sump and inspect. That’s my plan. Oil filter was as clean as any I’ve seen. Now if those hangar elves would just show up. 
Of course now that the engine is off come the list of “might as well’s”. New Lord mounts? Have engine mount bulletins complied with? Muffler?

[carusoam]

If the engine donuts are wicked old…. You might like a new set…. New rubber is better at absorbing vibration than old rubber….

Some people really like their PowerFlow exhausts….

Others like their OH’d original exhaust system…..

Both are good… especially if your old exhaust system is showing signs of wear…. Muffler wall, flame tubes…. Discoloration, missing parts….?

This is the #1 cause for elevated CO levels in the cabin….

Great opportunity to OH the engine mount…. Clean, inspect, repaint… looks brand new…. If adding updates for strength, search for interference issues…. (Seen around here somewhere)

Pp thoughts only, not a mechanic…

Best regards,

-a-

[Guest]

4 hours ago, BDPetersen said:

Pull sump and inspect. That’s my plan. Oil filter was as clean as any I’ve seen. Now if those hangar elves would just show up. 
Of course now that the engine is off come the list of “might as well’s”. New Lord mounts? Have engine mount bulletins complied with? Muffler?

With the sump removed you can work a small borescope up and past the crankshaft to get a look at the camshaft and lifters.  Cylinders can be changed anytime, the camshaft takes more work.

Clarence

[BDPetersen]

Well, that wasn’t as expected. Popped the sump off, we hoped to have an unobstructed view of the bottom end of the engine. You don’t. Can’t tell if some talented work with a flexible borescope would get a view of anything interesting.  Guess I’ll study the O-360 parts manual.

[A64Pilot]

12 minutes ago, BDPetersen said:

Well, that wasn’t as expected. Popped the sump off, we hoped to have an unobstructed view of the bottom end of the engine. You don’t. Can’t tell if some talented work with a flexible borescope would get a view of anything interesting.  Guess I’ll study the O-360 parts manual.

Yeah, your looking at the bottom of the case, but you can get a bore scope up through those holes in the middle. The cam should be looked at because you can now.

I’m a big fan of Copper coat for gaskets, I prefer the spray on kind. It’s nice and sticky but easily removed in the future.

[BDPetersen]

Thanks for the tip. I see a 3/8” slot I might get the scope through.

[Guest]

8 hours ago, BDPetersen said:

Well, that wasn’t as expected. Popped the sump off, we hoped to have an unobstructed view of the bottom end of the engine. You don’t. Can’t tell if some talented work with a flexible borescope would get a view of anything interesting.  Guess I’ll study the O-360 parts manual.

Now you’ll have an appreciation for how doctors do a colonoscopy.

Clarence

[MikeOH]

4 hours ago, M20Doc said:

Now you’ll have an appreciation for how doctors do a colonoscopy.

Clarence

Sorry, but I have ZERO appreciation for how doctors do colonoscopies!! 

[BDPetersen]

Hopefully not with a rigid scope.

So, for a Paul Harvey “rest of the story” moment, I note that while cleaning the flange of the sump, gasket had to be scraped off except for the portion on the aft edge. That part was shiny and mostly clean where the leakage was likely oozing from. And (bingo) that area was directly over the pad heater. The block portion of the heater had become somewhat detached from the sump, undoubtably causing poor heat control of the pad and likely allowing that area of the sump flange to become warm enough to compromise the seal. There was some evidence of red stuff (sealer) in that seam. I suppose the question is did that portion of the pad become detached or did the pad malfunction in such a way that it overheated, causing the detachment.

[pilot_jb]

Did no one else here notice that RTV was previously used when the sump gasket was installed?  Probably doesn't matter at this point, but did you check the sump bolts for proper torque?  With RTV under there, which it shouldn't be, the torque would have never been "correct" and will change over time.  

[A64Pilot]

I’d guess the RTV was from a previous attempt at fixing the leak from the outside.

[Guest]

9 hours ago, pilot_jb said:

Did no one else here notice that RTV was previously used when the sump gasket was installed?  Probably doesn't matter at this point, but did you check the sump bolts for proper torque?  With RTV under there, which it shouldn't be, the torque would have never been "correct" and will change over time.  

Even with a thin film of RTV on the both sides of the gasket, full torque can be achieved with no displacement of the gasket.  A pure silicone gasket would be a different matter.

Clarence

[BDPetersen]

I was aware of the RTV. Didn’t seem to be a red flag to those who saw it or that I mentioned it to.  Bolts were torqued. In disassembly, RTV seemed to be specific to one area, making it seem it may have been an attempt at a patch of some sort. Not a great idea but maybe it worked for awhile.

I take it some “enhancement” to the dry gasket is acceptable on reassembly?

[A64Pilot]

I like Copper Coat, very sticky, does help seal never hardens so it’s easy to remove. It and silk thread have worked well on case halves for me.

In my opinion silicone has no place on gaskets, the reason is because the way it reacts to fuel or oil, they soften it and it swells up.

However a thin layer of grease has always worked well for paper gaskets too for those adverse to any king of goo, and they have a point, good clean surfaces and properly installed you shouldn’t need anything, anything is really sort of a band aid unless the manufacturer specs something, just Copper Coat had worked so well for me especially on copper head gaskets on high performance motorcycle engines that I like it

[BDPetersen]

Got the Copper coat. Anxious to try. Well, anxious is probably too strong a word. Wish there was an aviation version of Garage Squad.

[Fly Boomer]

49 minutes ago, BDPetersen said:

Wish there was an aviation version of Garage Squad.

You found it!