O-320 exhaust valve guide wear

I am still not clear on what exactly is wrong with the valves / guides. Are they all carboned-up? Sticking? Loose?

From the original post...

I was going to try the rope trick and a valve lap.. but once I got the springs off I found the valve to guide clearance was like throwing a wiener down a hallway.

Click to expand...

The two I took apart recently were too tight. Running the cylinder too cold or too much lead, carbon or something. Reamed the guides, dressed the valve and seat and they were good to go.

Well that's gotta be the best $1200 I ever spent... it was close to being MUCH more expensive.

Lesson learned.. don't ignore a bad valve / compression test two years in a row... it's trying to tell you something!!!







As for the guides.. all four cylinders were about the same "weiner down a hallway" (so were replaced) but all seats were fine and just needed touching up.

You should go buy a lottery ticket
A little hard to see in the pictures but what did your mechanic think was the cause? Just the valve guide wear? It' been cleaned up but was the seat only hitting on two sides as if oblong? Looked shiny by the crack and the 180* away side. Finally 100LL the probable actual cause??

So are you concluding that the crack caused the valve to seat improperly and cause low compression, and also that it allowed the valve to wobble and ream out the guide?

All 4 exhaust guides are about the same.. so the valve crack has nothing to do with wearing them. The low compression was definitely from the cracked valve and even visually you can see that the section that is about ready to crack off is oblong and as noted above it was probably pre-seating on the two ends of the oblong and not the entire valve seat. Possible that air was even leaking thru the crack.

Just glad it was caught and maybe I will go buy a lottery ticket. At least it's one thing off my list of problems in life and I can get some comfort in that... the next problem to solve and fix.... my 25 year old daughter was diagnosed with Pelvic Sarcoma / Bone cancer this week.