Epoxy in Sump

[CBogle]

Guys:

Got the sump off today, cleaned it, and it appears to be in excellent condition. One thing I noticed right away is that someone put some type of epoxy on the bottom of the sump in the area in front of the carb tube. This was obviously done to keep that area from corroding and it appears to have done the trick. This epoxy like substance has been in there at least since the last major which was back in the early 60's.

My questions are:

1. The substance appears to be brown to olive brown in color and has a smooth texture like plastic (appears to have dried to a very hard consistency.) It is apparently not affected by the oil or heat within the sump. Does anyone know what this substance might be?

2. I need to remove the gasket which is stuck on very firmly. Is it best to scrape this off carefully with a razor blade or a sharp scraper? Is the magnesium surface easily harmed?

3. After I have the sump completely cleaned up using mineral spirits, should I spray it down with LPS for storage? I don't have any idea how prone to corroding magnesium is or how best to protect it.

4. Do these sumps need to be sent out to be yellow tagged or, are they an item that can be verified as good simply from visual inspection?

And another question regarding the accessory case.

I have the accessory case off but have not disassembled the oil pump. Should I disassemble that pump for storage or just leave it in tact within the accessory case? When I cleaned the accessory case with mineral spirits, I'm sure that some got in the oil pump as I was spraying all openings.

If the recommendation is to leave the oil pump in the accessory case, should I pour some LPS into the pump?

And my final question is...how is the pin that holds the piston to the connecting rod removed?

Thanks,

Curt

[Bruce Fenstermacher]

Curt you might as well disassemble the oil pump and clean and oil the impellers.

The piston pin should push right out of the piston and rod. Nothing holds it in place but the sides of the cylinder.

Boy oh boy I'd love to know what is in the sump. I've long thought an epoxy coating of some sort would work there to protect the area. I'd considered dong it to my sump at overhaul but then thought better of it.

[n1410d]

Although I can't be 100% certain, it sounds like a compound called PRC or Pro Seal. I have used it on rubber fuel tanks with great success. It dries to a greenish grey slick finish. Here is a link to the stuff.

http://www.aircraftspruce.com/catalog/c ... roseal.php

Patrick Mahaffey
N1410D
Grand Prairie, TX

[CBogle]

I heard there is a shop in Canada that repairs these sumps and as part of their process, puts an epoxy coating on the bottom interior designed to stop the corrosion problem. I don't have the name of this shop though.

I'm hoping that someone has an idea of what this stuff is as it seems to have worked very well and I have a couple of spots on the bottom of the sump that I'd like to cover with more.

Curt

[CBogle]

Patrick:

PRC sounds as if it is either the same stuff or would work. Do you know if PRC was around in the early 60's?

Curt

[HA]

Curt-

to get your piston pins out will probably require some pounding or other force, they get carboned in there and won't just slide out like when they were assembled.

I use a piece of hard plastic rod as a punch, nearly the diameter of the pin. you have to be careful not to sideload the rod too much, have a helper. I also made a pin press after a tool I saw in a catalog once, I used a piece of drill casing that goes around the piston with a fitting welded in one side and a hole for the pin to push through on the other. then you run a threaded rod through to push the pin out, I used a piece of some random Snap-On puller that my tool guy had laying in his truck. I put a piece of the plastic rod between the pin and the threaded pusher to save the pin. it works great when you're just doing one cylinder with no room for the hammer and punch method, but it's kind of a cluster all the same

[N171TD]

I have heard from what I consider reliable sources that JB WELD has been used to repair oil sumps. Might be material of this nature.

[Bruce Fenstermacher]

Yes JB Weld sounds more like the description and is readily available cheap.

Pro Seal I suppose can get hard but generally from what I've seen stays a little pliable but tough. If it's Pro Seal you will probably be able to dent it with your finger nail.

[CBogle]

Guys:

You could be right...it could be JB weld. The substance is harder than can be dented with a finger nail, but, the JB weld I've used in the past is grey. This substance is most definately somewhere between brown and olive green, leaning towards the brown. If it was JB weld and started out grey, who knows what 40 years under hot oil could do to the color? I don't.

Curt

[GAHorn]

Rolls Royce made/makes an epoxy called "Aryldite" (sp?) which was a grey/green permanent epoxy that is extremely durable, and used for metal tank/accy.-case repairs.

[mrpibb]

Araldite is one of the many variants of adhesives product ranges that are made by huntsman. fastweld, epicast and epibond are also made by huntsman. We stock some of the stuff at work, I have used some of the epicast for bedding the actions on some of my firesticks and the fastweld for building up window frames on jumbo jet liners. They make variants of each so it is tough to figure out which is best for what, i have been using the trial method because the price is right

[N3243A]

Beyond what type of epoxy was used to repair your sump is whether an epoxy repair is an acceptable method of repair. My engine overhauler just said "NO" to JB weld and the like. His reasoning is that it is much more likely to come loose and cause a major blockage in your oil system than a certified weld job as done by Drake Airmotive. This is in specific reference to "home brewed" JB weld jobs done in your garage with 6 pack of beer and a prayer. Did your prep the sump properly and mix the epoxy exactly in correct proportion, etc. What type of sump repair method does the outfit in Kelowna BC use?

Bruce

[N2865C]

Beyond what type of epoxy was used to repair your sump is whether an epoxy repair is an acceptable method of repair. My engine overhauler just said "NO" to JB weld and the like. His reasoning is that it is much more likely to come loose and cause a major blockage in your oil system than a certified weld job as done by Drake Airmotive. This is in specific reference to "home brewed" JB weld jobs done in your garage with 6 pack of beer and a prayer. Did your prep the sump properly and mix the epoxy exactly in correct proportion, etc. What type of sump repair method does the outfit in Kelowna BC use?

Bruce

I just got off the phone with Fred at Okanagan Aero Engines (O.A.E.) about their sump repair. It is an epoxy repair, not a fusion weld. According to O.A.E., they have been doing them for 5 or 6 years now and some have already gone to TBO and come back for overhaul again. The sump repairs have lasted and did not have to be redone. The only times the repairs have had problems is when it has looked like sombody, maybe the mechanic, has picked at the repair with some sort of tool to see what is in there. Even then they can be re-repaired. Otherwise they last, according to O.A.E.

They start by water/bead blasting the corroded/leak area to clean it up. No grinding tools or chemicals are used which could contaminate the repair area. The epoxy is applied and cured. Then a special paint is applied over the whole area where the repair was made and where future corrosion could occur. This paint is not affected by engine oil. The engines which have had the pan repair and have already come back at TBO still have the paint intact.

I asked if O.A.E. would clean and apply the paint to a good oil pan to inhibit corrosion. He said they do that but he has never seen one without some corrosion and no matter how little, their repair stops the corrosion and protects the metal all around the area.

The other pan I had was sent out for weld repair to a shop in Anchorage that does weld repairs on Magnesium pans. They have not been able to weld mine without having the repair area show small cracks under dye penetrant inspection. O.A.E. will not work on a pan that has been welded on because of the cracks that are there. I don't know of any other repair that might work, so it looks to me that O.A.E. is the only approved method left out there. We'll see how long their repair lasts. I'm betting it will.

Otherwise, with my other pan, it would probably be fun to cut it up into pieces and throw them into a camp fire. That should be impressive.
Richard

[CBogle]

Gentleman:

Just because one overhauler wouldn't epoxy a sump doesn't mean that it isn't an acceptable fix. Obviously, the epoxy in my sump, whatever it is, did the job of stopping corrosion in its track for 40+ years without any adverse affects. These sumps all corrode in this area unless something is done to stop it. The only process that I know of at this time that seems to do so is the epoxy.

Now, since I don't know what was used in my sump, if/when the time comes to use it again, I'll send it to the shop in Canada that is using this epoxy process with apparently great results.

After seeing how well my old sump held up in terms of no corrosion (and I mean none), I would feel better knowing that the sump in my newly overhauled engine was epoxied. What I do know for sure is that if it isn't epoxied, over the next 20 years or so, no matter how dilligent I am in changing oil frequently, etc., it is going to be slowing corroding, and, at some time, which is impossible to predict, it will corrode through. Not a pleasant thought. I wish my current sump was epoxied.

Curt

[N3243A]

Gentleman:

Just because one overhauler wouldn't epoxy a sump doesn't mean that it isn't an acceptable fix.

Curt, You are correct. As pointed out, Okanagan Aero does a yellow tag epoxy repair. However my post specifically stated that my overhauler would not accept an owner performed epoxy job or one done without a yellow tag for that matter. Any job of unknown origin is suspect. I have seen several examples of home brewed sump repairs in his shop and they looked like crap. That you have had good luck with yours is excellent news of the longevity of a well done epoxy job.

Your question No. 4 references if the sump needed to be yellow tagged or verified by simple visual examination. Well good question. My overhauler wanted my sump yellow tagged by a shop that specializes in sump repair. Maybe another overhauler will just take a look and say good enough.... I don't know if there are any "rules" regarding sump inspections at overhual.

Bruce