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Mike in MI 08-23-2012 19:22:41 74.36.237.161 Report to Moderator	Has anyone ever heard of cam bearing going bad in a JD 420 W/P220 Onan engine. I been hearing a fant squelling noise on my 420 when running an it almost sounds like the PTO clutch when you turn it off - it screeches. I decide to check it out and my first thought was the PTO so I removed pto clutch and starting it back up the sound was still there. I did notice there was oil leaking down from the crankshaft seal and I replaced that and at the same time i done a carbon remove on the heads. After putting all back together I noticed there still was oil leaking from the rear crankshaft seal. Again I thought I might of damaged the seal when installing it so I remove the pto again and as I was wipeing the oil off the block I noticed the welch plug that covers the cam shaft was loose. I went and got a magnet sure enough it fell out. I found out where the oil leak was coming from and also found out that the cam had a lot of end play and I could see a small piece of the cam bearing sticking outward from back of cam. After removing the engine from the mower and removing the timing cover and removing the crankshaft snap ring and lifters I pulled the cam out and both front and rear cam bearings was galled. Now the cam looks ok and the governor balls and plate are ok. thrush washer didn"t look to bad I mic it .060 not sure what new one mic"s at? I still don"t know where the end play on the cam coming from? Hopefully tomorrow my parts will be here? I ordered a new thrush washer and bearings. lower part engine checks out ok. Crankshaft end play was only .005 and i think your aloud up to .010 on that? Engine always had good compress around 124 to 130 lbs difference between the two. I"ll get back on this later Thanks Mike [Reply]   [No Email]
ken combs 08-24-2012 12:56:39 76.254.213.30 Report to Moderator	Re: JD 420 Cam Shaft Bearing Question? in reply to Mike in MI, 08-23-2012 19:22:41   Not real common, but it has happened to others. There are 2 different widths of cam bearings. A nice wide one used in early production and a much narrower replacement. If you can find some NOS wide ones they are much preferred. And, clean the bore well and use some locktite to prevent them moving again. [Reply]  [No Email]