R&R #4 cylinder

[sbav8r]

I am purchasing a 2002 172SP with 189 TT and the engine log says: compression check #4 cylinder 00/88, R&R #4 cylinder. What I would like to know is, what would cause an engine with such low time to have a cylinder removed? Is there any safety issues or potential for the problem to remanifest itself? Does this change the value of the aircraft or resale value?

Thanks in advance,

 

[USMCmech]

the engine log says: compression check #4 cylinder 00/88, R&R #4 cylinder.

It sounds like the cylinder wasn't holding any compresion. You would have to ask the owner why. Possibilities are valves that won't seat, rings not properly installed, ect. One cylinder being changed isn't someting to worry too much about provided it was properly done.


Why was 88 psi used for the compresion check? 80 psi is standard as far as I know.

 

[sbav8r]

Sorry I hit the 8 twice. You are right, it is 80.

Thanks for the insight.

 

[avbug]

Far from enough information is given to answer your question.

Axiomatically, it's not uncommon when replacing one cylinder on a horizontally opposed engine to end up replacing the opposite cylinder before too long. This is without regard to the cause of the replacement. Failure to seat the rings still shouldn't result in zero compression. Zero compression...big hole in piston, sucked valve, what? If so, what else was done to the engine?

I hate cryptically minimalized log maintenance entries like that. I do maintenance entries such that one reading it won't have any doubt as to what was done. Merely showing R&R on something doesn't help much, especially for those reviewing the logs later who don't know the history. The entries should be written with those folks in mind, the ones who know nothing about what has gone on but what is written in the logs. I'm big on details.

 

[NewBlue]

Ok Avbug, put down the theesawrus...uh theseras........uh that big book with all the big words in it. :>)

 

[avbug]

Big words, right. That would be "sucked valve," "big hole in piston," and multisyllabalistic words such as "horizontally opposed," or "zero compression."

Got it.

 

[NewBlue]

multisyllabalistic words such as "horizontally opposed," or "zero compression."

ARGHHH....brain overload..melt down imminent!

 

[USMCmech]

, it's not uncommon when replacing one cylinder on a horizontally opposed engine to end up replacing the opposite cylinder before too long. This is without regard to the cause of the replacement.

Just don't fall for the old "well why don't we go ahead and replace all 4 while we're at it" scam.

Your engine is actually four 1 cylinder engines conected to a single crankshaft. Most common cylinder problems are limited to that cylinder alone. Your #1 could have a compression reading of 40/80 and the rest could easilly be fine with readings of 75/80. There is no reason in this example to touch any of the other cylinders.

Many less than honest mechanics will try to convince you to give them extra work, and spend your money replaceing things that were in perfect condition.

Read this article from AVWeb

http://www.avweb.com/news/columns/188025-1.html