SE6601KF wrote:Don't get too excited yet.

When you put air to the cylinders where it it leaking from?
Can you hear it through the exhaust , intake or crankcase?

The cylinders may be repairable.

Maybe you can just get the valves ground ( or possibly just lapped) and or re hone the cylinders.

Bad cam wouldn't cause bad compressions. (although it's worth looking at as long as you are apart).

That is exactly right. Could be carbon stuck in a seat or guides. If the jugs are second or third run then the temptation would be great to replace. If they were new at overhaul with 800 hours then I bet you are OK. O470 is not nearly as prone to cracks as the injected ones. I seriously doubt you have any bottom end issues unless there was a prop strike at some point.

Good luck!

Hay Tim, on the leak down test was it leaking by the rings or valves? If it was the rings, then, Was the engine warm when you did the leak down test? Can you here the piston click as it goes past top dead center during the leak down test? If you don't here the click the rings are stuck, does the leak down tester have the correct orfice? does it use excessive amounts of oil? If its stuck rings Avblend in the oil, and if it were an old boat or car (not for use in aircraft) I would run Marvel Mystery Oil in the fuel and see if it dosent correct its self. Hope this helps.

172heavy wrote:Hay Tim, on the leak down test was it leaking by the rings or valves? If it was the rings, then, Was the engine warm when you did the leak down test? Can you here the piston click as it goes past top dead center during the leak down test? If you don't here the click the rings are stuck, does the leak down tester have the correct orfice? does it use excessive amounts of oil? If its stuck rings Avblend in the oil, and if it were an old boat or car (not for use in aircraft) I would run Marvel Mystery Oil in the fuel and see if it dosent correct its self. Hope this helps.

I did a bit more resurch, it seems that the FAA recomends an orfice of .060 on engines with bores 5" and above, yours is on the line I believe yours is 5", the difference between an orfice of .040 and .060 is twice the area, this could make a differance, were all cylinders low? Did you try a different gauge?