MooneyMark

M20K 252 Oil Consumption

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Thanks again to all who took the time to reply! I have taken in your advice and I'll talk it through with my mechanic again.

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Although I'm not at all sure, I take it my tech checked proper fitment of the checkvalves. I pointed them in that direction and he also mailed with Mooney concerning this matter, and he said they're okay and fitted correctly. I would just love to pop of the cowling and check it all myself, but I've decided to leave it to the pro's. I am wondering how 'pro' he is though, cuz he billed me one hour labor for swapping the landinglight... This I will do myself next time. 
So assuming the checkvalves are okay and the crankcase pressure is high, but within limits (they check this with an old ASI... never knew!) then that leaves the valvestem seals. Need to check if they did the boroscope.

Mark,
I like what you are thinking. Maybe it’s time to become the pro. Pop that cowl and see what you have. Your life depends on it. Just saying...

Aron

A&P, IA



Sent from my iPhone using Tapatalk

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Well, they checked the barrels and there is no excessive oil, and the exhaust before the turbo is clean. So the oil is added to the exhaust at the turbo. The checkvalves have been fitted correctly I am assured. They know about the specifics concerning their fitment and they have been leak tested overnight, so the valves are good, and fitted correctly. I've sent an e-mail to mr. Mike Busch by the way, but never got a reply.

Next thing on the list is checking the scavenge pump...

If the the pump is okay, maybe then it's time to take of the turbo for a rebuild?

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If you do send the turbo out I’d recommend Main Turbo in CA. Talked with them on the phone a couple times and they seem like straight shooters. 

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Dan-  I had my turbo replaced about a thousand hours ago (231).  The inside of the exhaust has always been completely dry.  I don't honestly stick my finger in the exhaust every time I pre-flight because of the mess, but I do it often.  I do open the turbo door and inspect the turbo and the clamps every flight, and I look for signs of oil.  No oil is normal, oil is not normal.

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13 minutes ago, MIm20c said:

If you do send the turbo out I’d recommend Main Turbo in CA. Talked with them on the phone a couple times and they seem like straight shooters. 

Ha, those are the same people my tech is dealing with at the moment. Good to know, thanks!

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Mark,

if the scavenge pump is good I would put new check valves in its way cheaper then the turbo.  There is one more thing to check. The hose from the turbo drain to the return check valve up to the scavange pump. You can have a internal flap of the rubber restrict flow in one direction. Long shot but worth checking. Good luck 

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Just had call from the mechanic, the scavenge pump is good, as a matter of fact it is part (apparently...) of the starter assembly that was changed out for a new one early this year. The checkvalves are only two years old and have been tested. I'll have a chat later about the return hose, thanks! I was thinking if the scavenge pump is good, then maybe it gets too much oil for the pump too handle. Although the capacity of the scavenge pump should be 140% of the volume of oil being delivered. Can the flow of oil in to the turbo be regulated? It should be 3 qrts in and 4 qrts out,

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After landing I let the engine idle for a few minutes to let the turbo cool, the mech suggested, since the turbo and ancillaries appear to check out fine, to let the engine run at 1400/1500 rpm for 30 secs before idle cut off. This allows for the scavenge pump to do its work better. Any thoughts?

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Mark,

Check the thread on turbo cooling.  APS has done some good instrumented work on that topic.

Give it a read. See if there is something in there for your set-up...

Best regards,

-a-

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