Lycoming - Can't Get Rocker Shaft to Re-insert

[Kyle Boatright]

I had a dented pushrod tube on my Lycoming O-320, so I pulled the valve cover, slid the rocker shaft out of that rocker, and removed the rocker. Then I removed, straightened, and reinstalled the pushrod tube. The problem is that I cannot get the rocker shaft to go back into the bore of the rocker - the rocker (engaged with the pushrod an valve) sits slightly proud of the bore. Is my only recourse to remove the pushrod tube again, extract the cup and the hydraulic adjuster and collapse the adjuster?

Note that I only removed one pushrod, so it isn't like I am attempting to reinstall the wrong length pushrod.

[Mike Switzer]

I haven't messed with Lycomings much, but is the cam turned to where the pushrod & lifter are in as far as they will go? Also on some engines if you compress the valve spring a little you can get it back together.

[Kyle Boatright]

I haven't messed with Lycomings much, but is the cam turned to where the pushrod & lifter are in as far as they will go? Also on some engines if you compress the valve spring a little you can get it back together.

Yep, the engine is rotated to where the valvetrain for that cylinder is "relaxed", for want of a better word. Otherwise, it is very hard (impossible?) to remove the rocker shaft in the first place.

[WLIU]

Not hard to pop the pushrod tube off and then pull the hydraulic lifter out with a hook of safety wire. Wash the oil oil of the lifter with solvent, collapse it, and put it all back together. No special tools required.

Best of luck,

Wes
N78PS

[Kyle Boatright]

Not hard to pop the pushrod tube off and then pull the hydraulic lifter out with a hook of safety wire. Wash the oil oil of the lifter with solvent, collapse it, and put it all back together. No special tools required.

Best of luck,

Wes
N78PS

Absolutely true, but the lead time on the little $1.25 anti-rotation tab that helps secure the pushrod tube retainer is probably 10 calendar days. I didn't expect to need extras...

[Mike Switzer]

I'd still try to compress the valve spring - you probably don't need much... Lisle makes a valve spring compressor for automotive use that you can use without removing the head, I bet it would work. I don't know if that is one of the tools a place like Autozone would have available to rent out or not.

[Kyle Boatright]

One of my resources built engines for a very reputable rebuild shop. His suggestion was to lever the valve open using a leverage tool - screwdriver or whatever, and slide the shaft in with the valve slightly open. Then, he explained the procedure to collapse the hydraulic lifter so I can check the dry tappet clearance.

It is good to know people who do this stuff for a living.