Lycoming cam inspection

[pa38112]

There has been much discussion about corrosion on Lycoming cams and the risk of buying a sitting engine. I have to believe there is a way to get a borescope somewhere to view the cam with-out splitting the case. I could not find a cut-away drawing with a quick search. Wouldn't one be able to fish a borescope up through the oil drain plug to view the cam lobes?

[131RB]

The easiest way is to pull a cylinder back for access.
Ryan

[snopercod]

[chevelle000]

On a four cylinder pull the #1 and #4 cylinders and look for any type of spalling.

[Flynfrfun]

Originally Posted by 131RB

The easiest way is to pull a cylinder back for access.
Ryan

If this is done, I've heard that you don't want to remove the cylinder completely from the piston. What kind of cylinder base gaskets do Lycomings have? Wouldn't that have to be replaced any time you unbolt a cylinder? Seems like you would have to pull the cylinder all the way out to get a gasket installed?

I ask this because I'm in the market for an RV and some have sat for extended periods and I would want a mechanic to pull 2 cylinders and verify no cam corrosion.
Josh

[Mel]

Originally Posted by Flynfrfun

If this is done, I've heard that you don't want to remove the cylinder completely from the piston. What kind of cylinder base gaskets do Lycomings have? Wouldn't that have to be replaced any time you unbolt a cylinder? Seems like you would have to pull the cylinder all the way out to get a gasket installed?
I ask this because I'm in the market for an RV and some have sat for extended periods and I would want a mechanic to pull 2 cylinders and verify no cam corrosion.
Josh

Cylinder base uses an "O" ring. The trick is to carefully pull the cylinder just past the wrist pin. Remove the wrist pin leaving the piston/rings in the cylinder.
This is not quite as easy as it sounds. The bottom ring is very close to the wrist pin. Goos Luck!

[Flynfrfun]

Got it...thanks Mel!

[pa38112]

Originally Posted by Flynfrfun

I ask this because I'm in the market for an RV and some have sat for extended periods and I would want a mechanic to pull 2 cylinders and verify no cam corrosion.

This is why I posed the original question. Not many owners are going to let you pull 2 cylinders, and you are risking a maintenance induced failure. If there is any way to inspect with a borescope, that would be the best.
The photo snopercod posted helps explain why this is difficult - thank you for sharing! - What about through the mag port?

[Ironflight]

Originally Posted by pa38112

This is why I posed the original question. Not many owners are going to let you pull 2 cylinders, and you are risking a maintenance induced failure. If there is any way to inspect with a borescope, that would be the best.
The photo snopercod posted helps explain why this is difficult - thank you for sharing! - What about through the mag port?

Nope - the Mag port won't get you to the cam lobes either. the only real way in to teh cam is to pull jugs. That's either a no-brained or a horrifying thought, depending on your experience.

If you have enough experience to do it, then its a no brainer. If the thought is horrifying....then you probably don't have the experience, and should hire someone who does.

Paul

[snopercod]

Originally Posted by pa38112

What about through the mag port?

Nope. That's no good either. Also, if you were thinking about the crankcase vent up front, you can't see the cam from there, either (ask me how I know).