Woolls01 Posted April 9 Posted April 9 Got a 1967 806 diesel. Had a loose sleeve so sleeve was replaced now that cylinders valves cannot be set correctly. The exhaust valve makes a hammering sound when adjusted to spec but quiets to a tapping when backed way off. If you tighten the intake valve down to almost zero clearance it hides most of the noise. The noise is all valve. Tractor starts and runs well but something clearly isn't right. Valves look to be in decent shape, I lightly lapped them before putting it back together. Guides were nice and snug. I don't believe these engines had much issue with cams/ lifters. All other components have checked out well. I've switch rockers and pushrods to see if that changed and nothing. I'm leaning towards weak valve springs since I likely brought the compression back up on that cylinder. Any thoughts? Quote
Woolls01 Posted April 9 Author Posted April 9 Also oil pressure is 55 lbs at idle cold and 50 hot Quote
Powered by IH Posted April 10 Posted April 10 2 hours ago, Woolls01 said: Got a 1967 806 diesel. Had a loose sleeve so sleeve was replaced now that cylinders valves cannot be set correctly. The exhaust valve makes a hammering sound when adjusted to spec but quiets to a tapping when backed way off. If you tighten the intake valve down to almost zero clearance it hides most of the noise. The noise is all valve. Tractor starts and runs well but something clearly isn't right. Valves look to be in decent shape, I lightly lapped them before putting it back together. Guides were nice and snug. I don't believe these engines had much issue with cams/ lifters. All other components have checked out well. I've switch rockers and pushrods to see if that changed and nothing. I'm leaning towards weak valve springs since I likely brought the compression back up on that cylinder. Any thoughts? Hello there, welcome! It's hard to say. You have to pull the valve cover off anyway (or have it off already), so please post pictures of everything. Try pushing down on all of the valves, and see if those 2 valve springs feel different. What is your clearance spec you are using? Are sure the exhaust noise isn't the valve hitting the piston? Keep us updated! 1 Quote
acem Posted April 10 Posted April 10 4 hours ago, Woolls01 said: Got a 1967 806 diesel. Had a loose sleeve so sleeve was replaced now that cylinders valves cannot be set correctly. The exhaust valve makes a hammering sound when adjusted to spec but quiets to a tapping when backed way off. If you tighten the intake valve down to almost zero clearance it hides most of the noise. The noise is all valve. Tractor starts and runs well but something clearly isn't right. Valves look to be in decent shape, I lightly lapped them before putting it back together. Guides were nice and snug. I don't believe these engines had much issue with cams/ lifters. All other components have checked out well. I've switch rockers and pushrods to see if that changed and nothing. I'm leaning towards weak valve springs since I likely brought the compression back up on that cylinder. Any thoughts? I wouldn't say these engines had issues with valves, cams or anything really. My 856 has not had the valve cover off since dad bought it in 1974. Injection pump has been rebuilt a couple times. Lots of hours of use. Quote
Woolls01 Posted April 11 Author Posted April 11 Okay so I have an update I had replaced one of the Pistons with an aftermarket piston and it looks like the valve recession wasn't exactly the same as the original piston. I can see that the Piston was making very slight contact with the intake valve. My diagnosis is that as I backed off the clearance on the intake valve it didn't open quite as soon so there was no contact but that starved it for air so it was sucking open the exhaust valve. Does this make sense? I cleaned up the old piston and reinstalled it hoping to start the tractor this afternoon. 1 Quote
MeanGene1 Posted July 16 Posted July 16 It's pretty common in the hot rod world to check the piston to valve clearance when changing components, usually when going to a larger cam. Pretty easy using some modeling clay, turn it over gently with the clay in the valve notch and then measure the thickness of the clay. If you can see marks on the new piston, you could take it to a speed/ machine shop and they can easily trim the piston to give adequate clearance. It's been done many times in home shops using an old valve with a cutting bit welded to it and spun with a drill. Sounds like a quality control problem on the new piston 1 Quote
MeanGene1 Posted July 16 Posted July 16 And nice looking tractor- in car circles that's called a "survivor"- hasn't been monkey-modified Quote
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