Oil leak

[a64pilot]

Check torque to the specs given (very important) normally those nuts will never loosen, if it checks ok I would try cleaning the stud/nut very good and try sealing the "outside" of the nut with proseal using a long screwdriver then let it cure for a couple days, I would try this first before pulling any jugs. Another possibility is the silk thread at stud has chafed away at the case half and allowed oil to seep through.

Nuts seem tight, I’ve built one or two motors and only used the thread between case half’s, thread and copper coat, I like copper coat. There shouldn’t be any thread under a cylinder?
Motors I have done had a red silicone O-ring that sealed the cylinder, slid over the liner and I don’t see how you could mess up that install?

The concern is that I have an old motor that this stud is I believe screwed into the opposite case half at the bearing support. The fear is that it’s broken a chunk of the bearing support off or I suppose it could have stripped. If stripped I’d expect it to be loose, and while I can’t get a wrench on it enough to really do anything, I’m pretty sure it’s not loose.

Anyway in my opinion I should pull the Jug, assumption is then I can tell if the case is broken or not, I assume if it is, the stud will wiggle a little?

[8175]

I seem to recall talking to an Aeroshell guy that their oils have a dye in them that will show up under a black light. Less messy than powdering the engine with talc or baking powder.
Larry Lowenkron

[6643]

I think Phil was referring to the thread that keeps oil from migrating up the stud to the nut.

If the bearing support is cracked the studs should exhibit play if you loosen the nuts. The surfaces fret enough that it will move. Also, an oil analysis will show bearing material if it's been going on for very long.

[a64pilot]

“Old” C-85’s have the studs screwed into the cases, parts manual refers to them as obsolete I believe.
“Newer” C-85’s have through studs
Surely there is a serial number break where the switch was made?
My engine S/N is 25495-6-12, if I knew where to look or who to call, surely I could determine if my engine has thru studs or studs screwed in to the case?

[6643]

It is my understanding that the through studs were introduced with the O200 and only replacement cases used on C-series engines have them.

[4004]

Jody:
Call Continental Tech Support, with your serial # they should be able to tell the date of manufacture and internal configuration of your specific engine.
However, I agree with John C re 0-200. See, if you had been flying behind TCMs rather than all those "big bore Lycomings" , you would probably be on a first name basis with the TCM folks now.

[a64pilot]

So how common is the busted case? How difficult is it to get a yellow tagged case? Can an 0-200 case be used?
What drives people ro discover the case being busted? Oils pressure, metal in the screen or leaks?

[6643]

Call Continental Tech Support, with your serial # they should be able to tell the date of manufacture and internal configuration of your specific engine.

As of the day it left the factory. My engine has the original dataplate. AFAIK, everything else is newer (including my case, with through studs), with the possible exception of a few gears and some hardware.

So how common is the busted case?

I personally have seen 3, and one broken crank (flying).

How difficult is it to get a yellow tagged case?

Don't know. I think it depends on the market at the moment.

Can an 0-200 case be used?

Yes, but you either need to get a field approval for mount adapters, or get the mount from a 140A.

What drives people ro discover the case being busted? Oils pressure, metal in the screen or leaks?

Usually it's a surprise. Leaks and copper in the oil analysis drive one do open it up.

case-2.jpg (167.63 KiB) Viewed 3111 times

case-1.jpg (297.29 KiB) Viewed 3111 times

[a64pilot]

As an update, it appears that my cases are thankfully. NOT busted.
It appeases on inspection that the cylinder base seal, sort of a flat O-ring, was rolled over on installation, meaning it was sort of pinched in appearance in one place and I hope that’s my leak.
part is .99c

Anyway I bumped into an interesting SAIB concerning unapproved procedures for preventing leaks when putting an engine back together and or installing cylinders that can lead to engine failures, as a min likely a $20,000 fix, if your lucky and get it down undamaged on a runway. If in a field of course add in recovery costs.
http://www.aero-news.net/index.cfm?do=m ... d35f8e32e6

Not trying it be dramatic, just be sure to follow the manual, and resist things that may seem to be a good idea.

[2066]

Thanks for the update -- hopefully that's the source. Maybe the gasket wasn't pushed all the way up (out) when the cylinder was installed & it somehow twisted a bit? Thanks, too, for the service bulletin RE sealers -- there are " field overhauls" and there are field overhauls done right -- that's a good reminder to be sure they're done by reputable shops/overhaulers who very specifically follow the latest applicable mfgr. specs.. Thanks for sharing the experience!