What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Worth dropping the sump?

bill.hutchison

Well Known Member
RV6A - ECI Titan O-360 motor. 1370-ish hours.

I've been chasing a couple of minor leaks over a few months. I've determined that the worst of the leaking is coming from a couple of bolts at the rear of the sump where it attaches to the bottom of the case, on the co-pilot side.

Suspect it has been a longstanding problem since there are a few gobs of permatex that the previous owner used, presumably to deal with this.

It's just enough to be messy but not enough to be a safety issue. I get oil dripping onto the bits of angle (I'm looking at the plans and can't figure out exactly which part this is) aft of the carb on the centerline, below the prop governor, above the slot for the nose gear that you cut in the bottom cowl on 63_6.

Yes, I've checked the prop governor. This is not the source of the leak. It's coming from bolts and dribbling down the case and pooling on those bits of angle.

The leak pools on the angle, drips to the aft lip of the cowl, and blows out all over the belly. Makes a mess.

I know this is subjective, but I don't know what I don't know: Is it worth the time and aggravation to drop the sump from the engine case and install a new gasket/seal?

Doing this would require removing the airbox, the carburetor, all of the exhaust, a bunch of linkages and probably some other things I'm not thinking of. Then it's a good bit of scraping permatex off and getting a new gasket and re-installing.

Would this be a viable repair? Or am I kidding myself about this and it's just going to leak because this is what Lycoming clones do past a certain age? Do I just live with the oil leak?

What would you do?
 
Last edited:
Dropping the sump is pretty easy. Getting it out is a bit harder, but you don't need to.
Drain the oil and let the plane sit for about two weeks so all of the oil drips down into the pan. If you don't wait it will drip down on the flange as you are trying to clean it to replace the gasket.
A head lamp will make it easier to see what you are doing, and have a couple of extensions for your ratchet (use 1/4" sockets) so you can come up through the bottom.
The whole job should be less than an hour.
 
A problem area is were the accessory gasket (vertical) meets the sump gasket (horizontal). The Accessory gasket is a bit long, and it is up to the installer to make the cut. Often it is a bit short, so some use things they shouldn't, like RTV. Lycoming has a service bulletin on proper ways to mate the gaskets. Not an approved fix, but some have had success with using electric contact cleaner to get all the oil residue off the gasket, and putting a dab of pro seal on the mating area. The downside is that you really don't want pro seal getting inside of the "go 'round" of the internal engine.

DAR Gary
 
Pulling the sump is a fairly simple job but yes everthing in the way will have to come off. I suppose it's possible to drop it down just enough to try and replace the gasket but honestly this will not be possible if the gasket is fused onto the two mating halves. The longest part for me when I pulled my sump was getting the old gasket off with a razor blade. Taking everything on and off is fairly simple though.
 
leaking bolts

Try this. Remove bolts, clean bolt holes maybe with a parts cleaner, get it as clean as you can, blow dry make sure it is completely dry. Use tite seal on the bolts toward the head of the bolt so that he excess will squeezes out from under the head when you tighten it. Ive done this on a Caterpillar truck engine and it worked for me. Just a thought
 
Try this. Remove bolts, clean bolt holes maybe with a parts cleaner, get it as clean as you can, blow dry make sure it is completely dry. Use tite seal on the bolts toward the head of the bolt so that he excess will squeezes out from under the head when you tighten it. Ive done this on a Caterpillar truck engine and it worked for me. Just a thought

Is Tite Seal a specific product or is that a generic term for some other kind of sealer?
 
Oil leaks

The suggestions so far have been reasonable. If you want to get tough with it and have a really good chance of success consider taking the engine off the mount. This route may be the least painful and be almost as quick as trying to work it in place. Leave the spinner, prop and baffles in place. Do the work with the engine on the hoist. Change all the gaskets and intake hoses. I like Hylomar as a sealant. A experienced guy with a little bit of help could probably get this done in a weekend. This is a great time to ream the nose gear and mount for a taper pin, that’s why the engine is off the 6A in the photo.

Don Broussard
RV9 Rebuild in Progress
57 Pacer
 

Attachments

  • 0C1C0D0E-242E-413E-A348-5BAD77D7469B.jpg
    0C1C0D0E-242E-413E-A348-5BAD77D7469B.jpg
    401.3 KB · Views: 145
Last edited:
The suggestions so far have been reasonable. If you want to get tough with it and have a really good chance of success consider taking the engine off the mount. This route may be the least painful and be almost as quick as trying to work it in place. Leave the spinner, prop and baffles in place. Do the work with the engine on the hoist. Change all the gaskets and intake hoses. I like Hylomar as a sealant. A experienced guy with a little bit of help could probably get this done in a weekend. This is a great time to ream the nose gear and mount for a taper pin, that’s why the engine is off the 6A in the photo.

Don Broussard
RV9 Rebuild in Progress
57 Pacer

Don - thank you. I think engine removal may be a bit beyond what I want to tackle right now, but I do see the wisdom of this method - it's definitely something to consider for the future, especially if I go ahead with the gear leg mod later.

I have a plan to replace the airbox (current plate is cracked and stop drilled and bugging me so I'm doing the new FAB-360 airbox project) so when all of that is dropped for replacement, it won't be THAT much more work to pull the carb and exhaust to remove the sump and replace the gasket.

And to all of you - thanks for the advice here.
 
A popular place for the pan gasket to leak is where it T's into the rear accessory cover gasket. It may be as effective to simply, leave it in place, clean the interface area and externally seal with tank sealant.
 
A popular place for the pan gasket to leak is where it T's into the rear accessory cover gasket. It may be as effective to simply, leave it in place, clean the interface area and externally seal with tank sealant.

While I am not 100% sure, I believe this was tried in the past given the sealant visible on the sump.

I think I am just going to have to bite the bullet.
 
FWIW, I was given the advice from a well know engine shop that one could apply a vacuum to the case and just put a dap of loctite 515 at the case seam. As the vacuum sucks it into the seam, release the vacuum. Wait a few minutes, then lightly pressurize the case and check with a soapy solution. Repeat as necessary. Their shop has a dedicated vacuum that is never used except to pressurize cases when required.
I haven't been retired long enough to do it yet, as it isn't anywhere near the the priority list yet. Perhaps as I get too much time available or the seeping worsens...:)
 
Aircraft supply has tite seal

Thanks - I'll check that out.

FWIW, I was given the advice from a well know engine shop that one could apply a vacuum to the case and just put a dap of loctite 515 at the case seam. As the vacuum sucks it into the seam, release the vacuum. Wait a few minutes, then lightly pressurize the case and check with a soapy solution. Repeat as necessary. Their shop has a dedicated vacuum that is never used except to pressurize cases when required.
I haven't been retired long enough to do it yet, as it isn't anywhere near the the priority list yet. Perhaps as I get too much time available or the seeping worsens...:)

That sounds like a cool solution but a bit specialized and not sure it's practical for my needs.

I'm feeling like a reverse-builder. :) I'm learning my RV not by building it, but by taking it apart and making repairs and improvements. So there is a part of me that *wants* to take it apart and learn all of the intricacies.

So now I'm going to hunt down the sump gaskets and stuff and figure out the right SB that talks about how to do this.
 
Wanted to post an update to this thread since I got a lot of good advice.

I did successfully get everything opened up and got the sump dropped from the plane. Took me about 4 hours, working really slowly and taking a lot of pictures and writing down the order of everything I did. It actually wasn't as hard as I thought it would be, just time consuming and required some creativity with extensions, u-joints and ratchets to access some of the bolts and stuff.

Since I had everything apart, I decided to clean the sump entirely...there was some sludge in there. Spent a lot of time with razorblades and scotchbrite to get the mating surfaces spotless and readied for the new gasket. Also decided to replace the oil drainback hoses with new hoses and proper clamps that were discussed in this older and very interesting thread.

It should have occurred to me - and it didn't - that TiteSeal is pretty thick stuff, and moreso when it's below freezing temps in the hangar. Solved that problem with careful application of heat from a heat gun to soften it up, then quickly applied to the places specified in the manual - mostly where the accessory case flanges meet the case. I also added a couple dabs toward the front where I knew it was leaking a bit, too.

I ran out of lockwashers (and time) so I'm going to finish putting everything back together in the next day or so, re-fill her with oil and hopefully my leaks will be, if not eliminated, at least reduced. It was nice to cut away all the old RTV that had been used on it in the past.

I did find one leak source at one of the case half bolts on the lower seam. I'm debating about taking out that bolt, and then putting either some silicone or Loctite 515 or titeseal in there and re-torquing it to see if it stops.
 
A copper washer will fix it

snipped
I did find one leak source at one of the case half bolts on the lower seam. I'm debating about taking out that bolt, and then putting either some silicone or Loctite 515 or titeseal in there and re-torquing it to see if it stops.

Bill, remove the bolt and replace the steel flat washer with an appropriately sized copper washer. The copper washer will act as a washer and as a gasket. Copper washers are commonly used to seal rubber brake hose connections on your car/truck. No worry about trying to get the surfaces clean enough for a sealant to work.
 
Not a good idea.

Bill, remove the bolt and replace the steel flat washer with an appropriately sized copper washer. The copper washer will act as a washer and as a gasket. Copper washers are commonly used to seal rubber brake hose connections on your car/truck. No worry about trying to get the surfaces clean enough for a sealant to work.

Did you know that Continental had an SB about using a thin layer of RTV under the barrel flanges? The thin layer compressed and expanded with each rev and that tiny movement fatigued the flange base bolts.

What makes copper a good gasket makes it a very bad washer to spread the load of hold that case together. I can't say what the answer is for the leak, but this is in the wrong direction. IMO.

One caveat: If it is attempted, then the torque should be rechecked several times until the copper has work hardened to retain the load, which is the washers prime function. If it keeps coming loose, then restore the steel washer.
 
Did you know that Continental had an SB about using a thin layer of RTV under the barrel flanges? The thin layer compressed and expanded with each rev and that tiny movement fatigued the flange base bolts.

I'm not familiar with the term barrel flange - is this a term for the case bolts?

In which case, you're saying that Continental said not to do the sealant method I was considering?

I just want to make sure I'm understanding this.

As for a copper washer, I never knew that. Interesting.
 
I'm not familiar with the term barrel flange - is this a term for the case bolts?

In which case, you're saying that Continental said not to do the sealant method I was considering?

I just want to make sure I'm understanding this.

As for a copper washer, I never knew that. Interesting.

Barrel is a term synonymous with cylinder. The SB was discussing the 4 studs/nuts that hold the cylinders, via there base flange, to the case.

Larry
 
Did you know that Continental had an SB about using a thin layer of RTV under the barrel flanges? The thin layer compressed and expanded with each rev and that tiny movement fatigued the flange base bolts.

What makes copper a good gasket makes it a very bad washer to spread the load of hold that case together. I can't say what the answer is for the leak, but this is in the wrong direction. IMO.

One caveat: If it is attempted, then the torque should be rechecked several times until the copper has work hardened to retain the load, which is the washers prime function. If it keeps coming loose, then restore the steel washer.

Bill,
Comparing RTV to copper is a poor analogy. The copper washer work hardens when the bolt is torqued. That is why any time you want to reuse a copper sealing washer, you have to anneal it first. Rechecking the torque after a time may be wise, but in my experience, has never been necessary. I've never heard of a manufacturer requiring torque rechecking on the banjo bolts used for fluid connections [like the joint between your car's brake calipers and rubber hoses or the electric fuel pump in your RV, assuming it's fuel injected].
 
Down the rabbit hole. sorry.

Bill,
Comparing RTV to copper is a poor analogy. The copper washer work hardens when the bolt is torqued. That is why any time you want to reuse a copper sealing washer, you have to anneal it first. Rechecking the torque after a time may be wise, but in my experience, has never been necessary. I've never heard of a manufacturer requiring torque rechecking on the banjo bolts used for fluid connections [like the joint between your car's brake calipers and rubber hoses or the electric fuel pump in your RV, assuming it's fuel injected].

The analogy was to the point of making a TLAR design on an engine component that results in unintended consequences, admittedly off center. A Conti cylinder base is sealed by an o-ring. I can imagine someone adding RTV as "what can it hurt" as a rhetorical question rather than a serious one. After all, it works for valve cover gaskets. My thinking was to show we should not do unproven things to loaded engine fasteners and joints - - it was not clear. I will try to do better.

The function of a case (steel) washer is to spread the load from a steel nut to aluminum and last for several hundred million loading cycles, all within the fatigue limits of the case as the weak link. Just throwing a copper washer on there is an experiment unless that has been done and proven as workable (being able to retain the load and not fail the case at the edge of the through hole). If it does come loose, the the case halves will shear and fret.

There are steel washers with a captured o-ring in the center that might fit and might work. It would limit the experimentation to the sealing function. Even the copper is going to have a hard time sealing against the threads, just like the o-ring will.

I'm not familiar with the term barrel flange - is this a term for the case bolts?

In which case, you're saying that Continental said not to do the sealant method I was considering?

I just want to make sure I'm understanding this.

As for a copper washer, I never knew that. Interesting.

Bill, I am sure that sump as some structural function to the case, but I don't anticipate anything wrong with your sealing method. At worst, it just would leak, but don't think it will. It was only the case nut that carries so many load cycles that gave me pause for an alternate method of sealing. It is sealed at the case split by silk or o-ring. Hopefully it was not loose, a different issue.

The Conti reference was to a highly loaded fastener for the core engine. I.e. the cylinder base to case bolt, not the through bolt.
 
Last edited:
FINISHED

Finished this project a week ago.

Here's the results - good and bad news.

Good news:

Sump does not seem to be leaking anymore at the flange, front or back.
I replaced the drain-back hoses while I was in there and used proper clamps on them.

Bad news:

I do still have a minor leak, but the amount I'm dealing with is less than before.

I am almost POSITIVE that the leak(s) is/are coming from the front 3 ventral case bolts at the seam. I've toyed with the idea of pulling them, putting some tite seal or silicone in re-torquing to see if that helps, but I don't know yet.

I flew it a fair amount over the last week and a half, and now I'm tearing things down to do the panel upgrade, so I may attack those bolts while I've got it opened up for new sensor placement.

Anyway. That's the saga of dropping sump.

Yes, it was a PITA.
Yes, I learned a lot doing it.
 
Back
Top