Sunday, November 7, 2010

Chipped lifter

Here is a shot of the chipped lifter which we removed from my left engine.  It shows the corrosion on the lifter too, which is the slight pitting that you see on the face of the metal.

It's interesting since it is likely indicative of the what the rest of the lifters look like.  They really should be perfectly smooth.  If indeed the small amount of metal I found in the screen came from the Cam, it's likely that these rough spots caused by corrosive pitting are wearing away or "eating" at the Cam lobes.  If all this sounds like Greek, which it did to me before I owned an airplane, maybe this image will help.

The Cam is the pipe on the top which has these oblong lobes on it.  As the engine turns the Cam spins with it and is timed so that the lobes move these lifters or "tappets" which are connected to rods which open and close the fuel intake and exhaust valves in time with the engine.  Apparently the level of pitting on my lifters isn't all that bad for a 1400 hr engine since Continental doesn't recommend replacing them unless more than 10% of the face has pitting.  Hard to tell but the worst area in the bottom right region looks like 10% or less to me and this was one of the worst lifters in the engine.  The rest were the same or better.  We replaced it due to the chip in it and I left the rest alone.

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