john deere f910 valves won't stay adjusted

[Yellowfever440]

My father in law has an f910 with the p220g onan engine and 1100 hours. Last year it started losing power and one cylinder quit firing and we figured out it didn't have compression. Well that cylinders valves had come far enough out of adjustment that it was holding the valves open. So he adjusted and went on. This year the same thing happened to the other cylinder so he adjusted them and within 20 hours now they have both lost there adjustment. Anyone else run into this and if you have what did you do to correct it? I'm assuming he will need new lifters so they hold there adjustment.

 

[beenthere]

Does sound like the came out of adjustment due to wear, and are just wearing more. New may be in order now.

 

[Yellowfever440]

I wouldn't think they come wear that much in 10 to 20 hours of use. That's only a couple mowings.

Someone has mentioned looking at the seats a little closer.

 

[beenthere]

That too would make sense.

 

[JD420]

I would go through and re-adjust the valves and try agin. Just to make sure you didn't get them misadjusted the first time. I can see the valve seats causing an issue but if that were the case I would think you would have a problem even after they have been adjusted. ( engine misfire, valve train noise ,etc.

When you adjusted them the first time did you follow a service manual procedure. I adjusted the valves on my b48g onan and found when you tighten the jamb nut it wanted to turn the Tappet causing the gap to get to tight.

 

[Gator6x4]

It takes some pressure to lock or secure the locking nut on the adjustment. Make sure after adjustment the nut is not just being snugged down there is a lot of vibration in the valve train when a engine is running. Vibrations makes thing move or loosen.

https://www.youtube.com/watch?v=slMP05G8LnQ

 

[Yellowfever440]

You must not actual have an onan like that and also this will make me sound like a jerk but there isn't a lock nut. You should watch the video you posted again. He holds the lifter with a 9/16 and turns the adjusting bolt or stud as some call it, with a 7/16. They are interference threads so they don't have a lock nut. He would of had to go back and tighten the lock nut after he adjusted each valve and doesnt. He turned the engine over check to make sure the lifters moved freely and he had to adjust the first one 2 times then he went to the exhaust valve.
Maybe I missed something in the video but I never heard him say jam the lock nut or tighten a lock jut.

 

[Yellowfever440]

Well something has caused one of the intake valves to get so hot the seat has melted down into the block, this is a flat head engine.

 

[Kyle_in_Tex]

Sometimes a mouse nest or a mud dauber's nest will block air flow and kill an engine.

 

[Yellowfever440]

The air intake for the flywheel fan is clear and clean and there isn't anything to block the air flow inside the air shrouds. The only thing we found was the rubber plug around the engine oil filter relocation lines wasn't in place. It was there just not the way it should of been.