[Hawkeye7A]

During my annual a couple weeks ago I found a cylinder that had a compression reading of only 54/80. The last three annuals all four were 78 or 79/80. I discussed the problem with Aircraft Engine Specialists in Chandler, AZ and they suspected a worn valve guide. The leakage was heard and felt coming from the exhaust pipe (Vettermans). I pulled the cylinder on Friday, shipped it to them on Monday. By the time we got through the "phone tag" on Wednesday, they not only had the cylinder, but had already repaired it! (The culprit was, indeed the exhaust guide.) They shipped it Wednesday, I had it on my doorstep Thursday evening when I got home from work, and installed it Friday. All this, and the final damages were well under $200 including shipping both ways! I've dealt with this shop several times in the past and they have never failed to deliver. As to why the guide went bad after just under 400 hours, they weren't sure; it just sometimes happens usually due to excessive heat. Bottom line, I'm a happy camper and if you're in need of some quality engine work, I can't say enough good things about them.

 

[jrs14855]

valves

There is substantial evidence that running oil pressure in high green will greatly alleviate valve/ valve guide problems on the Lycs. I ran my 0 360 Pitts this way for over 1000 hours, many times at 3600 r/m, never a problem. Cessna on the new airplanes since restart of single production, takes the oil pressure from the front of the oil gallery. This means that the "real" oil pressure is 10 psi more than indicated on guage. If you search there is a lengthy dissertation on this and the benefits to valve lubrication and cooling.