Engine making metal...the rest of the story
Posted: Sat Feb 18, 2012 9:46 am
Some time ago, I reported that my M-14P was showing metal in the
Aviation Development Corporation (ADC) oil screen. As I reported, some
folks told me it wasn't any big deal, as these engines are legendary
tough. Another guy told me he wouldn't even taxi it. I talked to folks
all over the country about this, including the ADC folks. This was
supposedly a brand new engine with, at the time, about 120 hours.
Finally I decided that I'd check the compression and have the engine
bore-scoped, at least in the lower cylinders. Wanting a knowledgeable
opinion, I flew the plane to Allen Tinnes and his folks at Lamar,
Colorado. They looked at the metal in the screen with the roughly 5
hours I had on it since last cleaning and said there was definitely
something going on that needed to be traced down.
Compression was low in two cylinders (#5 & #8), with an obvious exhaust
valve leak on both during the compression check. With their comment,
"We need to get to the bottom of this," I decided to have them tear
things apart (ouch!). All nine cylinders off only showed 4 broken
rings. Why would there be 4 broken rings after only 120 hours on a new
engine? Still no sign of what was causing the metal though.
Took off the front accessory case. Metal in there. Drained the oil
tank; more metal in the bottom of that. Finally, took off the oil pump
and found a loose nut in the pump! Where did that nut come from? A
"Friday afternoon special" from the Romanian factory? That mystery will
probably never be answered.
I took pictures of the nut. Other folks took pictures of the gears and
pump. Pictures are posted here:
http://www.i1ci.com/Flying/OilPump.html. Sorry the pictures of the
gears are fuzzy. You can see that the top land's are really worn down.
Sooner or later the pump would have failed. How the nut didn't lodge
between the housing and the drive (?) gear is a mystery (minor miracle
perhaps).
I have about 14 hours on the engine now since replacing the oil pump.
Virtually zero metal is showing now.
Allen Tinnes, at Lamar, Colorado, and his folks did an outstanding job!
I highly recommend them (contact me off list if you want their contact
information). These folks really know the M-14 inside and out (my
engine in particular <grin>).
Ted Waltman
N142SR
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Aviation Development Corporation (ADC) oil screen. As I reported, some
folks told me it wasn't any big deal, as these engines are legendary
tough. Another guy told me he wouldn't even taxi it. I talked to folks
all over the country about this, including the ADC folks. This was
supposedly a brand new engine with, at the time, about 120 hours.
Finally I decided that I'd check the compression and have the engine
bore-scoped, at least in the lower cylinders. Wanting a knowledgeable
opinion, I flew the plane to Allen Tinnes and his folks at Lamar,
Colorado. They looked at the metal in the screen with the roughly 5
hours I had on it since last cleaning and said there was definitely
something going on that needed to be traced down.
Compression was low in two cylinders (#5 & #8), with an obvious exhaust
valve leak on both during the compression check. With their comment,
"We need to get to the bottom of this," I decided to have them tear
things apart (ouch!). All nine cylinders off only showed 4 broken
rings. Why would there be 4 broken rings after only 120 hours on a new
engine? Still no sign of what was causing the metal though.
Took off the front accessory case. Metal in there. Drained the oil
tank; more metal in the bottom of that. Finally, took off the oil pump
and found a loose nut in the pump! Where did that nut come from? A
"Friday afternoon special" from the Romanian factory? That mystery will
probably never be answered.
I took pictures of the nut. Other folks took pictures of the gears and
pump. Pictures are posted here:
http://www.i1ci.com/Flying/OilPump.html. Sorry the pictures of the
gears are fuzzy. You can see that the top land's are really worn down.
Sooner or later the pump would have failed. How the nut didn't lodge
between the housing and the drive (?) gear is a mystery (minor miracle
perhaps).
I have about 14 hours on the engine now since replacing the oil pump.
Virtually zero metal is showing now.
Allen Tinnes, at Lamar, Colorado, and his folks did an outstanding job!
I highly recommend them (contact me off list if you want their contact
information). These folks really know the M-14 inside and out (my
engine in particular <grin>).
Ted Waltman
N142SR
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