Hello everyone-
Question for the engine guru's out there. Coming back from OSH I had a brief "morning sickness" on cylinder #4 at fire up, and had one 15 -20 sec stuck exhaust valve (EGT's dropped quickly) and then she came back to life and was fine the rest of the trip.
After a quick VAF research on what the problem really was, the reamer and exhaust wizard valve compression tool arrived today. I did not do a pre-ream wobble, but will build a fixture to text post.
Running my borescope through the guide I see what appears to be some galling on the top of the guide, even after reaming. I've got the ball hone on order, but wanted to see what the VAF brain trust would do. Hone? Run as is? pull jug and replace the guide? there is also a small amount of pitting on the stem too.
Any idea what would possibly cause this? It almost looks like it pulled the chrome out of the bore of the guide if that is possible.
Lycoming IO-390 (not T-bolt/EXP) 260 hours total time. All oil sampling has been great, no issues whatsoever up to this one and compressions all fantastic.
Thanks in advance
Question for the engine guru's out there. Coming back from OSH I had a brief "morning sickness" on cylinder #4 at fire up, and had one 15 -20 sec stuck exhaust valve (EGT's dropped quickly) and then she came back to life and was fine the rest of the trip.
After a quick VAF research on what the problem really was, the reamer and exhaust wizard valve compression tool arrived today. I did not do a pre-ream wobble, but will build a fixture to text post.
Running my borescope through the guide I see what appears to be some galling on the top of the guide, even after reaming. I've got the ball hone on order, but wanted to see what the VAF brain trust would do. Hone? Run as is? pull jug and replace the guide? there is also a small amount of pitting on the stem too.
Any idea what would possibly cause this? It almost looks like it pulled the chrome out of the bore of the guide if that is possible.
Lycoming IO-390 (not T-bolt/EXP) 260 hours total time. All oil sampling has been great, no issues whatsoever up to this one and compressions all fantastic.
Thanks in advance
