More problems on the 425 Kohler CH25

[Modrob]

More from the valve area:

 

[Modrob]

Waiting on parts to arrive…in the meantime, here are more pics of the cylinder head and stuff…

 

[Modrob]

Rough looking, huh?

 

[Modrob]

Also, that exhaust valve seat that was a little cocked, I tapped in back in ok…

 

[MTGreen]

Also, that exhaust valve seat that was a little cocked, I tapped in back in ok…

Hmm -"tapped back in"? Those should need a press or some pretty firm "tapping" with a drift to seat. This could be part (or all) of your problem if the seat is coming out. Remember the coefficient of heat expansion is different for the head than the valve seat so it may stay now and fall out when the engine heats up. I would consider either replacing all 4 of them or at least removing the seats and center punch peening the ID of the valve seat bore in the head to tighten up to a firm press fit

Here's an explanation of what I'm talking about with bearings but the same principle applies:

How to Make a Loose Bearing Race Fit Snuggly into a Housing

Whenever a bearing is replaced, the race it rides in should be replaced too. Learn how to make a loose bearing race fit snuggly into a housing.

www.grainews.ca

 

[Modrob]

Hmm -"tapped back in"? Those should need a press or some pretty firm "tapping" with a drift to seat. This could be part (or all) of your problem if the seat is coming out. Remember the coefficient of heat expansion is different for the head than the valve seat so it may stay now and fall out when the engine heats up. I would consider either replacing all 4 of them or at least removing the seats and center punch peening the ID of the valve seat bore in the head to tighten up to a firm press fit

Here's an explanation of what I'm talking about with bearings but the same principle applies:

How to Make a Loose Bearing Race Fit Snuggly into a Housing

Whenever a bearing is replaced, the race it rides in should be replaced too. Learn how to make a loose bearing race fit snuggly into a housing.

www.grainews.ca

Ahhh…good catch. I wouldn’t say it was an “easy tap-in” as I delivered short, sharp blows to a socket that fit exactly around the seat. But, I will try that peening method too.

 

[Modrob]

The plot thickens LOL…pics yesterday from cylinder 1…

 

[Modrob]

More…in my hand is a small metal rod that was laying on top of the piston, along with a couple of small “dark colored wads of thin fibrous material”…looks like the valves show some marks where it was bouncing around in there…I don’t have a clue…

 

[Modrob]

Received the gasket sets this morning…2 more lifters to rejuvenate and then let’s get it back together and see what happens.

 

[ponytug]

Wow! That would explain a lot, like the loose valve seat. I doubt that the pin was doing anything good. Is it possible that it fell in during a spark plug service or compression test? (As in, it was in the hose for the compression tester and fell into the cylinder?)

Thanks for the posts.

All the best,

Peter