We overhauled the engine our JD 4450 because of oil consumption and blow-by. The engine has 8,800 hours, which is a lot of hours for an ag tractor engine without being overhauled. The engine is rated at 158 HP and has not been modified in any way.
The oil consumption and blow-by was caused by bore polishing. The cause of bore polishing is a complex topic but it's fair to say in this case the polishing was mostly caused by carbon deposits on the ring lands. The worst build-up was on the ring land between the compression rings, but there was some build-up between the second compression ring and the oil control ring and some above the first compression ring.
The original Schwitzer turbo had too much shaft end-play and was replaced. No parts are available for this Schwitzer turbo, so we replaced it with a new Garrett turbo. The fuel injectors were all rebuilt. The overhaul included all new liners, pistons, bearings, and clutch. All measurements of the head were within spec, so the head had no work done. The rear tires were also just replaced at a cost of $2000 each. The total cost for the engine overhaul was around $10,000.
John Deere 4450
Completed overhaul
New Turbo
New Injectors
Looking into the removed liner from the bottom. All liners had severe polishing. In the ring swept area there are no cross-hatches left and the surface has linear scratches and is polished to a nearly mirror finish.
Close up of the boundary of the ring swept area and the area at the bottom of the liner that is only swept by the piston skirt. There is a slight ridge worn at the boundary. There is a considerable ridge at the top of the liner, but the ridge didn't need to be removed to remove the pistons during disassembly.
Carbon deposit build-up on the ring lands and above the top compression ring.
Very robust wrist pin.
Piston bowl and valve cut-outs.
Oil control ring drain holes and another good shot of the deposits on the ring lands.
Oil drain holes
Dimensional shots of the pistons. Notice the skirts are over 1/4" thick and are almost full length skirts. The piston assembly with rings and wrist pin weighs 6.6 pounds!
The bearings were worn and definitely needed to be replaced.
The oil consumption and blow-by was caused by bore polishing. The cause of bore polishing is a complex topic but it's fair to say in this case the polishing was mostly caused by carbon deposits on the ring lands. The worst build-up was on the ring land between the compression rings, but there was some build-up between the second compression ring and the oil control ring and some above the first compression ring.
The original Schwitzer turbo had too much shaft end-play and was replaced. No parts are available for this Schwitzer turbo, so we replaced it with a new Garrett turbo. The fuel injectors were all rebuilt. The overhaul included all new liners, pistons, bearings, and clutch. All measurements of the head were within spec, so the head had no work done. The rear tires were also just replaced at a cost of $2000 each. The total cost for the engine overhaul was around $10,000.
John Deere 4450
Completed overhaul
New Turbo
New Injectors
Looking into the removed liner from the bottom. All liners had severe polishing. In the ring swept area there are no cross-hatches left and the surface has linear scratches and is polished to a nearly mirror finish.
Close up of the boundary of the ring swept area and the area at the bottom of the liner that is only swept by the piston skirt. There is a slight ridge worn at the boundary. There is a considerable ridge at the top of the liner, but the ridge didn't need to be removed to remove the pistons during disassembly.
Carbon deposit build-up on the ring lands and above the top compression ring.
Very robust wrist pin.
Piston bowl and valve cut-outs.
Oil control ring drain holes and another good shot of the deposits on the ring lands.
Oil drain holes
Dimensional shots of the pistons. Notice the skirts are over 1/4" thick and are almost full length skirts. The piston assembly with rings and wrist pin weighs 6.6 pounds!
The bearings were worn and definitely needed to be replaced.
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. I’ve worked on a lot of tractors mostly New Holland though as that’s what my farmer friend has.