8KCAB Oil change tips

Big Ed

Big Ed

N50247 - '79 Super D
Joined
Jul 20, 2020
Messages
1,938
Location
Tampa, FL
Just had the local on-field A&P teach me how to change the oil and rotate tires. While the tires went well, it was pretty clear he had never seen an inverted oil system before. All we did is drain from the quick drain fitting and fill. That raised a few questions that I would like to resolve before the next time, which I will attempt myself.

1. The instructions I saw mentioned draining small amounts of oil from several fittings at the separator. How important is that, and how hard is it?

2. I don't have a filter. I know I'm supposed to clean a screen and inspect it for metal, but he did not show me that today. Where is it and how do I do that?

3. I bought a metal check kit. Any tips on using that?
 
2. There is a finger screen (Christen System) at the back of the sump. Use care in removing - I never find trash on it.

It holds a plug with an O-ring. When that plug comes loose or the O ring leaks, you will not have inverted oil pressure. Worse, when you roll rightside up, it will take several seconds to get pressure back.

If anybody has these symptoms, remind me and I will get my notes and publish.
 
Any chance you have any pictures or diagrams of where the finger screen is and how to access it? I am totally unfamiliar with that part of the engine.

Am concerned about checking it because my airplane sat unused for several years. I expect the camshaft and lifters to start making metal at some point.
 
I may have a diagram. Have a seat on the right side of your engine. You will see a shuttle valve, with three hoses. The center hose is the oil pump suck hose, and it goes into the back of the screen, you disconnect that at the screen, then carefully back the screen out. It has been a while - so I need to double check that.

The other two hoses are the oil supply - one from the bottom of the sump and the other from the top of the case where a vacuum pump would ordinarily mount.
 
Oh - while you are at it, clean out the shuttle valve. You do not have to do that if inverted flight is on your regular schedule, but if it sat for a while, do it before inverted flight. I think there are "balls" in there - been a while, since I exercise mine once a week.
 
OK, I do know where the shuttle valve is, so I should be able to follow the middle hose back to the screen. Thanks!
 
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