yanmar ym 2000 won't start

spyder2 · Oct 6, 2006

Gary
Are you sufficiently comfortable that you followed as close as possible to the same procedure in testing the compression on both cylinders? The reason why I ask this is that I agree with the posts on using the rubber tipped compression tester. It could be that you got close to the same readings because that is as hard as you were able to hold the tester down. If you got the 300 reading on the front cylinder then compression is probably not your problem. Also did it feel to you as if one of the cylinders was not blowing as hard as the other one or did anything sound different when testing either one? I would first ensure that the pump is in good working order and that the injection timing is set properly before tearing into the engine. Good Luck

garyd · Oct 6, 2006

Hello TBN
I didnt feel the compression test was very accurate asthe test Iam using is hand held. The test would almost be blown out my hands. I fabricated a hold down and went to home depot bought a new smaller tip for the gauge. Retested both cyclinders. 225 psi was High and repetable one the front, 300+ maybe 325psi on the rear. Its the injectors! no I think its the pump! No I think its the rings! Man I feal like a pancake flip, flop! I think the head going to come off. What do you guys think ? Thanks and have a great day!
Gary<><

normde2001 · Oct 6, 2006

Now, it's time to pull the head, and most likely the oilpan and front piston.

kenmac · Oct 6, 2006

You'er ok . I think you've found the problem . 225 is too low . Like was said pull the head & oil pan so that you can knock that piston out

normde2001 · Oct 6, 2006

I don't know how much engine work you have done, but if you don't find any major problem with the valves and have to knock the piston out, be sure and mark the rod and cap so they go back together the same way they came apart if they will be re-used.

Jagmandave · Oct 7, 2006

OK, more clues.............

It happened while working, to me that means a mechanical failure of some sort, spun bearing, broken piston rings, bad valve or something. I agree, time to take it apart and take a look...........

garyd · Oct 9, 2006

Well the bad news is in, I've pulled the head off and dropped the pan off the block. I should have noticed the fine metal on top of the head when I adjusted the valves, didn't see it didnt want too I suppose. The top of the front piston #2 has the the imprint of the head on it. rod bearing spun its all most gone. The crank shaft journel looks bad too. I dont know what should be done next, If it were a pickup or a car it would be a complete tear down and rebuid as the metal of the bearing has run through the motor. One good thing the cyclinder liners look good. I dont know why the bearing failed.What do you guys think I should do next? Tear the motor down the rest of the way pull the crank see if it can be turned? Can you get over sized bearings? Thanks for the input.
Gary<><

mark777 · Oct 9, 2006

Gary,

If it were me, and I had no hole or micrometer gauges I would split the tractor, pull the engine and disassemble everything. Take the block, crank, piston and con-rods to a competent shop for inspection. They will Hot Tank, measure for taper in the cylinders, check for warped head (or block deck) and it should run around $200 or less if you stop them at that point.

Rods can be resized in the event you need a replacement (used) crank or your original welded and turned crank journal. There is a point where machine shop labor, parts and a partial or complete overhaul vs. a good low hour used engine should be considered. There are cheaper ways to do this but I'd think you only want to do in once.

After reading your posts, IMO you seem more than capable to do just about everything necessary...outside of Zy-glo or magna-fluxing parts and intricate measurements. Good Luck!

Mark

Inspector507 · Oct 9, 2006

I wonder if that is related to your low oil pressure problem last year.

normde2001 · Oct 9, 2006

garyd said:
Well the bad news is in, I've pulled the head off and dropped the pan off the block. I should have noticed the fine metal on top of the head when I adjusted the valves, didn't see it didnt want too I suppose. The top of the front piston #2 has the the imprint of the head on it. rod bearing spun its all most gone. The crank shaft journel looks bad too. I dont know what should be done next, If it were a pickup or a car it would be a complete tear down and rebuid as the metal of the bearing has run through the motor. One good thing the cyclinder liners look good. I dont know why the bearing failed.What do you guys think I should do next? Tear the motor down the rest of the way pull the crank see if it can be turned? Can you get over sized bearings? Thanks for the input.
Gary<><

That's a problem with long distance troubleshooting, we can't hear it run. That thing had to be noisy as the dickens. I would inspect the crankshaft closely to determine if it is really bad, or just has material transferred from the rod bearing. If the latter it can be cleaned up and you would just have to deal with the front piston rod and cap.