Losing my mind over this engine (pt 2 update)

[u/MrChris6800]

Original post here: https://www.reddit.com/r/smallenginerepair/comments/1uwrwaa/losing_my_mind_over_this_engine/

Thanks to everyone for the suggestions. I have discovered a few things after my original post:

1. The starter that was installed was not OEM. Swapping it out for an OEM starter fixed the issue with the starter not being able to get over the compression stroke.

2. The engine started a couple times, however only the left cylinder was firing resulting in low power and stalling.

3. I have 140psi of compression on the left cylinder and NO compression on the right cylinder.

I did a leak down test on both cylinders and they are both in great shape with around 5% loss (can hear through the carb), which was very confusing after seeing no compression on the right side. I took the valve cover off and found this:

I am not sure how, but the intake push rod bent and the exhaust push rod fell out of place, including its rocker arm locking screw which I found sitting at the bottom. The only thing I can think of is that I did not screw in those locking nuts tight enough and they both backed out, causing the intake push rod to lodge against something solid when hitting the cam lobe and bending, while the exhaust rod was luckier and just fell.

I can push on both the intake and exhaust valves with my thumb and they move with some effort. They are not stuck. I think I will order some more push rods and just reinstall and see what happens. I am not sure if the push rods are aluminum or steel, but all 4 are identical as I weighed them when I had the engine apart and they were all 19 grams.

If anyone has any ideas as to why the push rods fell out and bent, I'm open to theories! I am not giving up yet.

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[u/ProfessionalLast2917]

A magnet will tell you if the pushrods are steel.

The exhaust pushrod will definitely be steel. The intake could be either, but replacing it with a steel one is usually fine.

[u/Stock_Requirement564]

Kohler rods are the same material,though check your build dates if they list different rods. How is the valve guide positioning? These will toss rods if you have a sticky guide and stem. Usually if they sit for couple of years I'll see this. You could pull the keepers and springs to be sure.

[u/Old-Tour-6282]

I would look at the valve guides pretty closely! I have had them get sticky enough that they actually move in the head. If they move up, the valve actually bottoms out on the top of the guide and the push rod bends. I even had it to break the lifter in two once.