My 580f with a david brown engine was smoking badly and was nearly impossible to get started. Dissmanteled the engine and installed new pistons and rings, the old ones was in bad shape and the rings was in pieces. Still with new rings the crankcase vent still smokes a bit, not as much as before, but I think this is wrong. Also the top cover is leaking oil through bolt holes and around the gasket. So clearly there is too much pressure in the oil system. Is there something that can cause this other than the piston rings? Or what can be the issue?
The crankcase vent smoke (blowby) could be caused by worn valve guides, the rings not being seated, or the cylinders being too worn. Did you measure the cylinders, either with an inside micrometer, or by using the endgap on the piston ring at a few places up and down each cylinder? How many hours does the engine have on the new rings? Did you work it hard enough in the break in period? If you can do a leak down compression test, and then squirt a couple shots of oil into the cylinder and rotate the crankshaft around to spread the oil, then repeat the leak down test, how much better the cylinder holds pressure is how much the rings are leaking.
Havent measured the cylinders, it is only been running about 1.5 hours on the new rings. So there is a break in period? And the top rings, did not have any markings, and was completly square, so it was installed either way?
Remove a valve cover and look carefully at the valve stems where they exit the guides with the engine running. I am guessing that you will see the blow-by there. You removed broken piston rings and did not install new cylinder sleeves ? Is that correct ?
I will do that, yes that is correct new piston and rings and not sleeves. They looked fine, but I did not measure them. The tractor have only been running 3200 hours total. I did notice that the valves are not correct adjusted .
Don't run it very long without adjusting the valve lash. Tight ones may be part of your problem.
Just my 2¢, did you hone the sleeves? If not, the rings will never seat.
Yes I did hone the cylinders
You should have noticed the ridge at the top of the cylinders before and after the honeing, if that wasn't too bad then you'll probably be OK as far as the cylinder being worn. Did the old pistons come out without too much pounding? It's common for rebuilt or new engines to use a little oil and then stop using as much as they break in. There are "special" break in oils. And there's even a tale on here of a Cat bulletin on how to use Bon Ami scouring powder to seat the rings on a new/rebuilt engine that is slobbering oil. So there's still hope, 1.5 hours is still early. Work it hard.
It was a ridge in the cylinders, I could bearly feel it after the honeing, like I had to search and really consentrate to find it. The old pistons I pushed out easily. The engine could run with the old pistons, I did drive it home, but it was hard to start, nearly impossible and smoked alot, fog all around under load. That is the reason I took it apart. The metal between the piston rings had broken loose someplace on 3 of 4 pistons, and almost all the top and second rings where broken. But everything was in place, did not fall out before I got the piston up and out. How many hours is normal break in time? and the oil I need to change after a little while, is that correct? Adjusted valves right now, clearance should be 0.254mm on all valves. Some had over 0.60 when I messured. Had it running for 15-20 min could not see any blow-by through valve stems.