Oil Sump Corrosion

[Richgj3]

Good news. Glad you got it done. Sorry you had to pay that much but I guess it is what it is, as they say.

It sounds better if you say the price was only 1.5 AMU’s. One Aviation Monetary Unit equals $1000

[snicholson]

I figured I would share some pictures of my sump which was repaired by Okanagan Aero Engines about 200hrs ago. The epoxy coating didn't adhere to the magnesium and began peeling off. I noticed this while changing the #6 cylinder. Not saying that this is a problem with all of their repairs, but it's worth taking a look if you have a sump that has been repaired by them. I imagine a large piece of epoxy breaking off could easily block the oil pick up and cause oil starvation.

- Scott

[n2582d]

How do you spell A D ?

Talk about a great first post Scott! That's an impressive catch to see the paint flaking at the bottom of a dark oily sump. Did you have paint chips in the filter or screen? What does Okanagan Aero Engines have to say? Seems to me that this should require a mineral spirits rinse and borescope inspection through both sump drains at next oil change for every sump that has been painted by Okanagan.

[GAHorn]

There has been years of commentary by very respectable folks who state the oil sump is made of magnesium….and like others, I’ve believed it because it was so-commonly stated by these folks. However, the TCM/Continental Ovhl Manual X30013, page 7, paragraphs 6 and 7 state that the oil sump is Aluminum…and the Crankcase-Cover (Accy cover) is Magnesium.

[mmcmillan2]

Wow, I’m glad I didn’t go with the epoxy repair. Thanks for sharing.

[n2582d]

There has been years of commentary by very respectable folks who state the oil sump is made of magnesium….and like others, I’ve believed it because it was so-commonly stated by these folks. However, the TCM/Continental Ovhl Manual X30013, page 7, paragraphs 6 and 7 state that the oil sump is Aluminum…and the Crankcase-Cover (Accy cover) is Magnesium.

George,
Airworx Aviation, an FAA authorized repair station, says the sump is magnesium. I don't know what sort of material they use in their High Velocity Oxygen Fuel (HVOF) coating procedure but I would think, in order to avoid future dissimilar metal corrosion, they would know what the sump is made of.

Note that the overhaul manual also says that the engine mount legs are aluminum. The common understanding is that they are magnesium. Also note that the Continental Overhaul Manual covers not only the O-300 but also the C-125 and C-145 engines. My guess is that Continental made changes to the metals used in these parts over the years. They may have started production using aluminum but switched to magnesium at some point. The sump on the C-125 may be made of aluminum. Here's why I think this may be the case. Several years ago I found a sump that was sold as a C-145-2 sump.

Click to Enlarge

Click to Enlarge

By the Sharpie writing on it, it came off of a 1948 C-170, N3914V. Because of some undisclosed corrosion on the mounting flange I was refunded my money on it. Anyway, there are several unusual features on this sump that made me question whether it really was a C-145-2 sump and whether it is magnesium or aluminum:
1.) Both drain plugs are 5/8"-18 rather than the standard 1"-18 plug in the rear. The forward drain plug area is raised which precludes the bottom 3/16" of oil to drain there. Compare this to the picture Richard posted here.
2.) there is no baffle in the intake T. It is not missing; it was never installed.
3.) Note the red paint on the inside. This is Glyptal which we discussed here. Factory original paint? Who knows.
4.) The IPC says the sump assembly p/n is 530763A1. The "A1" on that part number indicates that it is an assembly number, i.e. there are attaching parts. My sump has "6638" cast into the rear face, not 530763. Floating around the internet is the attached Continental A&C-Series Aircraft Engines Parts Interchangeability Catalogue. There it says, "Original part number for the C125 (sump) was #6638-Al." According to Continental this 6638 p/n has been superseded an additional three times. Could one of these supersedures involve a change from aluminum to magnesium?
5.) It did not fizz when I applied a drop of vinegar to it. Magnesium should fizz, aluminum should not.
6.) It weighs just shy of 6 lbs. Anybody have a C-145-2 or O-300 sump for comparison?

[N2625U]

I've got a 5 bolt sump from an O300C engine off of a 1963 C172 that had a leak. Thinking of sending it out for repair just to have a spare. What pics would you like?

[GAHorn]

Gary, the X30013 manual also states that the C125 sumps do Not have the Baffle in the intakes… but C145/O300 does.

[Richgj3]

I’ve got what is said to be a C145 sump in my hangar. Three bolts. I’ll take pictures tomorrow. Can’t get out there today.

[n2582d]

I've got a 5 bolt sump from an O300C engine off of a 1963 C172 that had a leak. Thinking of sending it out for repair just to have a spare. What pics would you like?

Jim, Could you take a picture of the back end? It should have “530763” or “653797” cast on that face. To determine whether it’s magnesium or aluminum, according to Continental, a drop of vinegar should fizz on magnesium but not on aluminum. On a digital postal scale mine weighed 6 lbs. I’ve read magnesium weighs 2/3’s that of aluminum. If mine is aluminum and yours is magnesium, your sump should weigh around four pounds.

Gary, the X30013 manual also states that the C125 sumps do Not have the Baffle in the intakes… but C145/O300 does.

Thanks George, I missed that.

[ghostflyer]

About 25 years ago i was witness to a refuelling accident to a 170 rag wing which caught fire . There was very little left but a discussion between myself and the insurance assessor did center around what’s was left and how to dispose of it. One thing that did surprise me was it had a wooden prop. The sump area including the Carb area after the fire was just a small amount of white powder residue . The insurance guy pointed out that this was a magnesium fire in this area. So all these years later i have assumed that the sump was magnesium. Plus my own experience in handling my sump was it was so light . I removed my sump once to clean it internally . [not an easy job]. The glug on the inside and other bits that were in there really surprised me .

[Richgj3]

Pictures of my spare sump. It weighs 5lbs 14oz on the kitchen food scale. It is a Three bolt sump. It says 6638 AU on the back. It came with a case for a C145-2 s/n 4322-9-2 as far as I can make out. No guarantee the case and the sump were ever a pair but I was told they were. I don’t have the accessory case. That’s corrosion X inside.

[Richgj3]

Gary, the X30013 manual also states that the C125 sumps do Not have the Baffle in the intakes… but C145/O300 does.

George

I’ve posted pictures of the sump I have. Where should the baffles be that are in the C145 sump vs the C125 sump? The picture I posted doesn’t show that area but I can take a look if I know what I’m looking for. I suspect I might have a C125 sump as it is aluminum.

Thanks
Rich

[Richgj3]

Here’s a picture. Is this the baffle?

[GAHorn]

Just above the carb mounting…yes.