Continental 220 Radial duplex oil pump?

[bob turner]

Asking here and on the Stearman forum. I noticed a roughness on base leg the third time around the pattern, and called for a full stop. Not the mags (all new).

Next day the mechanic noted that oil was down below one gallon. After thinking a bit, and not noting any oil on the airframe - just a little excess at the prop and alternator seals - I suggested a failure of the scavenge system.

Aircraft is now in the shop - sure enough, about three gallons of oil came shooting out of the plug on front of the engine case, and hydraulic lock noted on the lower cylinder.

There is some dirt in the scavenge area - I am not actually involved except to check very casually on a daily basis. None of us are experienced radial mechanics, although the shop has replaced cylinders, mags, carbs, starter - simple stuff.

So the question: are there any tricks to removing/checking the duplex pump/check valve, etc? Any other hints from folks who do this for a living? The shop may call Pete at Air Repair, but they say they hate to bother him if they are not buying stuff. I am not that reluctant, but thought I would ask here first.

Thanks - Bob

 

[RaisedByWolves]

A surprise check in the mail as a thank you for your help goes a long way. Sorry I couldn’t be of more help with the oil pump.


Sent from my iPhone using Tapatalk

 

[AKjurnees]

Pull the check valve at the oil pump. Might be something on the face, carbon or something, Just remember how many turns to take the nut off the spring.

if it looks clean you might need to send the whole pump in for inspection.


Those do wear out, my old one would drain the oil into the case if it sat a month, I thing last I heard it was $$$ to replace it with rebuilt.

On that note, it shouldn’t have affected the running of the engine, if it’s a cause of the roughness then something major is about to happen.

 

[bob turner]

Thanks. Yes, I am a bit worried about that. We did clean some junk out of the check valve area, and will do a test flight this weekend.

 

[Steve Pierce]

Had the scavenge pump go out on an 1830 on a DC3 years ago. Lower cylinders filled with oil and got lots of people excited from the smoke it created.