I bought another JD950 but it has an engine problem. It is a 4WD tractor with power steering and a good loader.
I pulled the pan tonight and the number 2 rod bearing was gone. Crank is pretty beat but no deep grooves. Not sure whether it will turn. i think I'll split this tractor and get the crank to the machine shop. I'm debating as to whether I should do a full overhaul or repair as needed. I guess I'll decide after I see how good the balance of the engine looks and price the parts. I like doing things right but I don't want to spend a ridiculous amount of money.
I thought I would call the junkyards to see if they have any decent used engines. I don't have high hopes but you never know.
I have the tractor split and the engine removed. I pulled the crank tonight and the no. 2 rod journal is galled but seems to be close to standard diameter. I'll let the machine shop do the official measuring but I have high hopes the crank is serviceable. Luckily I figured out some of our local machine guys that have been in the business about 30 years are still turning cranks.
I have not pulled the cam or sleeves yet but I think I need to get the block all the way down for a good cleaning. This engine did eat a rod bearing. In my circles we call this making metal. It did make an impressive amount of metal. I need to get all the contaminants removed from the block and galleries.
These Yanmar blocks have an orange coating on the inside. I assume it is to seal the casting but I'm not sure. Does anyone know what this is? Is it paint? I'm assuming I would not want to boil this block as it might remove this coating. Anyone have any experience with this? I stopped at the local Deere dealer today and they didn't know either.
Tractorless, 2019 Toyota Tundra, 1980 Toyota Land Cruiser FJ40
This is very interesting but I can't offer much help because it sounds like you know more about engine internals than I do. Yanmar makes a **** good engine. I'm surprised to hear one came apart like that. I wonder what caused it?
Things are moving slow on this rebuild but here is an update. Machine shop says the number 2 rod journal on the crank is 15 under before turning. Rod bearings are available .030 over so I still have high hopes. The head needs an exhaust valve but is otherwise serviceable. I'm now leaning towards an overhaul kit from Weaver Tractor that includes liners and pistons. Obviously all the bearings will be replaced. The cam looks ok but I intend to have it and the followers polished. I pressure washed the block but will probably take it to the machine shop Thursday. We won't boil it as I don't want to remove the paint on the inside of the block. The gears look new thankfully. The radiator is done and flows good. The next project is to turn some steel to remove the front and rear bearings and seals. I measured the diameters tonight and dang that's a big rear bearing.
I guess so far so good considering this engine made a lot of metal. All the old bearings have metal embedded in them. Probably be a couple of weeks before I collect all the parts and components.
This is very interesting but I can't offer much help because it sounds like you know more about engine internals than I do. Yanmar makes a **** good engine. I'm surprised to hear one came apart like that. I wonder what caused it?
Hard to say for certain but I think the previous owner didn't take very good care of their oil. This likely led to spun bearing and a loss of oil pressure. The number 2 rod shows signs of heat. My grandpa always said that oil is the life of your engine. Not that I ever doubted him but I believe this proves he was right.
The other thing I have noticed on the two JD 950 engines I have been inside is that the head bolts don't seem to be staying tight in the block. I marked these head bolts before turning the nuts and 7 out of 8 studs turned with 4 coming out with the nut. It's just my opinion and I realize everyone has one but I think these studs need to be carefully checked anytime a head gasket is replaced on these Yanmar engines. I intend to discuss this with my machine shop but I'm giving serious thought to installing these studs using red Locktite. I'll see if the machine shop has a better idea.
The other thing I have noticed on the two JD 950 engines I have been inside is that the head bolts don't seem to be staying tight in the block. I marked these head bolts before turning the nuts and 7 out of 8 studs turned with 4 coming out with the nut.
I believe this is the way it's supposed to be. If you turn the head studs tight into the block there is distortion in the block as not all the threads are holding the load evenly.
This project is finished so I thought I would update this thread. I split the tractor and did a complete overhaul on the Yanmar 3T90j. I bought the overhaul kit from Weaver which included new pistons and sleeves. The sleeves looked great, the Pistons were a little rough and required some clean up. I did not use the head gasket from the kit, instead I bought a head gasket from Deere. There is a major difference quality.
The engine runs great and I delivered it to my barn today.
I did also reseal the front 4WD hubs so they no longer leak. I used a .010 repair sleeve on the spindle so I didn't need to increase the hole size in the hub.
The power steering is awesome and I have already put the 75 loader to use a couple of times during the first weekend of use.
