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Al

Quiz, What is the answer??

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Al
Hi, We received a JD 335 with a Kawasaki in the shop. Engine had low power and was missing. Good spart to both cylinders. Diable 1 plug, no change diable the other, dies. No compression on one cylinder. Removed engine and head. This is what we found. I had never seen a valve like this before. It took a little while for me to figure out what the problem was. Customer purchased the tractor nearly new from JD dealer, and has used it 3 years with noproblems. By looking at the picture see if you can see the cause. Note: The tappets all had clearance, and this is not the cause. Will geve the solution in a day or two. By what ever happened with the Briggs that wouldn"t turn over. Thanks Al Eden

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Leroy
Al By the looks of that head, id'e say the carb sucked up Spiderman. I guess i duuno what that expando material would be doing in there but if the intake is obstructed that would reduce power. The high carbon content would indicate bad gas or weak spark, or wrong plug type and gapage.

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D-17_Dave
Hard for me to see the details of the pic, but looks as if somethng built up between the valve and head. Mayby bent the valve. Was the head gasket seated properly and holding or was this a leaking valve?

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ReedS
Looks like the valve overheated and either burned or broke up. Never seen a valve in quite that condition. Looks like the valve is quite a bit larger than the seat. Is the valve wrong or is the seat wrong? Did someone assemble the head incorrectly putting the intake valve where the exhaust valve should be? In either case the valve (after a second look) isn't transferring heat to the head therefor burning the valve.

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Al
Bingo, The exhaust valve which is a stellite valve is in the intake port and sunken because of the diameter. The intake valve which is not stellite is in the exhaust port. The intake overlaps the seat and is not a high temp material. Once the valve started leaking the extreme temperatures caused extreme disintegration and flowing of the lower grade material. Since the valves often operate in the 1500 to 1600 degree range, the exhausts have to be of very hi temp compatable material. The only cooling the exhaust valve gets is the contact with the seat for about 2/3 of the time the rest of the time it is in the flame front. The intake gets cooled by the incoming a fuel mix and can be of less exotic material. The person is fairly certain that the tractor has not been opened up before. This engine may have left the factory this way. Thanks for looking. Al Eden

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