Finally got time to tear into our 1967 4020 diesel, syncro, with a M&W turbo that I had asked you guys about a couple months ago. The general idea was that it was a piston with broken rings. Well, we tore into it and all the pistons, liners, and rings are fine and installed in the proper direction (as they came to us as "loaded" liners, with the pistons and rings already installed in the liners)
We also took the head back to the shop where it was done up 2 years ago when we overhauled the tractor, and everything checked out on it.
HOWEVER, when we removed the head, there was a LOT of carbon build up on #1 & #6 piston, head, valves. #2 & #5 had buildup, but not as much. #3 & #4 had basically no build up, the parts were just black, but no layer (up to around 1/32", not actually measured) of carbon buildup.
Before we tore it down, we plumbed shop air into one injector hole at a time to try to ascertain where any leaks would be, and we noted on a couple cylinders there was a lot of leaking out of the valves, usually the intake. So we tapped on the valve with a rubber mallet and we could eventually get it to stop leaking. We checked the springs, and they felt definitely weaker than new ones so we changed them all out. In the end we figured the leaking valves was due to the carbon buildup, but also could have been due to weak springs.
The guy who did the head rebuild suggested that the rings needed to be replaced as the buildup on the head was far more than normal and they were not seating, allowing too much oil up in the combustion area. So we pulled the pistons to look at the rings, however, the rings look good and all were installed in the correct slot and in the correct direction (dots toward the top). So we do not really see a problem with the rings, but we are not exactly experts on the subject.
Just a little recap:
Engine overhauled late 2015
New liners, new pistons, new rings, new valves, reground seats, new valve guides, new bushings on rods
Plasti-gauged main & rod bearings, all checked out on the tight side of allowed tolerance
Engine dynoed, however, PTO clutch was weak and slipped, so we could only run it around 40HP for 1hr. (yes, we forgot the linkage adjustment to tighten it) The transmission clutch has been weak for many years, but we only do light work with it so never a problem, so we knew we could not pull it to break it in fully.
Now we also have split the tractor while we were working on the engine, and fixed the clutch so that we can actually just pull it to seat the rings fully (hopefully).
What are your guy's thoughts on the rings, or what do you think is causing our oil usage in the tractor. It has run 230hrs since overhaul and we have had to add over 2.5 gallons to it in that time.
Sorry for the long post, I just want to be thorough.
Thanks,
Matt
We also took the head back to the shop where it was done up 2 years ago when we overhauled the tractor, and everything checked out on it.
HOWEVER, when we removed the head, there was a LOT of carbon build up on #1 & #6 piston, head, valves. #2 & #5 had buildup, but not as much. #3 & #4 had basically no build up, the parts were just black, but no layer (up to around 1/32", not actually measured) of carbon buildup.
Before we tore it down, we plumbed shop air into one injector hole at a time to try to ascertain where any leaks would be, and we noted on a couple cylinders there was a lot of leaking out of the valves, usually the intake. So we tapped on the valve with a rubber mallet and we could eventually get it to stop leaking. We checked the springs, and they felt definitely weaker than new ones so we changed them all out. In the end we figured the leaking valves was due to the carbon buildup, but also could have been due to weak springs.
The guy who did the head rebuild suggested that the rings needed to be replaced as the buildup on the head was far more than normal and they were not seating, allowing too much oil up in the combustion area. So we pulled the pistons to look at the rings, however, the rings look good and all were installed in the correct slot and in the correct direction (dots toward the top). So we do not really see a problem with the rings, but we are not exactly experts on the subject.
Just a little recap:
Engine overhauled late 2015
New liners, new pistons, new rings, new valves, reground seats, new valve guides, new bushings on rods
Plasti-gauged main & rod bearings, all checked out on the tight side of allowed tolerance
Engine dynoed, however, PTO clutch was weak and slipped, so we could only run it around 40HP for 1hr. (yes, we forgot the linkage adjustment to tighten it) The transmission clutch has been weak for many years, but we only do light work with it so never a problem, so we knew we could not pull it to break it in fully.
Now we also have split the tractor while we were working on the engine, and fixed the clutch so that we can actually just pull it to seat the rings fully (hopefully).
What are your guy's thoughts on the rings, or what do you think is causing our oil usage in the tractor. It has run 230hrs since overhaul and we have had to add over 2.5 gallons to it in that time.
Sorry for the long post, I just want to be thorough.
Thanks,
Matt