Implications of an engine not properly laid up

[Fearless Tower]

Lifting a concept from another thread.....what are the implications of an engine that was not laid up/pickled properly and sat for an extended period of time (say a year or two) with occasional ground runs?

Most of us seem to be in agreement that it is less than ideal, but if you were considering an aircraft with such an engine, would you make an offer based on immediately pulling the engine and having it overhauled or would you make a discounted offer with the expectation that the engine probably won't make it to TBO?

IOW, would you be concerned that the result of improper lay up would lead to catostrophic engine failure or just reduced engine life?

Discuss....

 

[Jim Logajan]

Those "occasional ground runs" do far more damage than just letting it sit. Combustion gases get past the rings and since they contain water, a mix of water and oil results and forms acids in the crankcase that eat the engine alive. If an engine flies it will get hot enough long enough to boil that moisture off.

Sorry for being stupid about this - but what if the engine is run a long time on the ground? Would that make any difference?

I ask because on the one hand I read posts and articles saying that idling an engine while waiting a long time on the ground before taking off can cause engine overheating, and now on the other hand I read about running on the ground not getting the engine hot enough to boil moisture off.

And on the third hand I've seen the same people write that flying an engine often is good for it.

I think I've run out of hands.

Pointers to some outside credible sources would be a nice start.

 

[Jim Logajan]

Sorry, I have no pointers.

I found this Lycoming service letter, which is authoritative enough for me:

http://www.lycoming.com/support/publications/service-letters/pdfs/SL180B.pdf

EDIT: And here is the Teledyne Continental letter:
http://www.tcmlink.com/pdf2/SIL99-1.pdf