yanmar ym 2000 won't start

normde2001 · Oct 5, 2006

"At one point I pegged the gauge at 300 psi. I also blew the top of the prechamber up and out of the injector port. "

Sounds like you are getting incorrect readings with with the wrong gauge, (pegging at 300psi is a good clue). You should see 320-330psi, (I believe the YM2000 is 22/1 compression, X 15psi, would be 330psi.

Jagmandave · Oct 5, 2006

Well, erroneous or not, he said he got 300 psi on the front cyl and that's the one that causes the engine to die when he loosens the injector line, so it sounds to me like that's the one that's doing all the work and keeping the engine running, ergo his problen is with the other cylinder, right?

He also thought he was getting comparable readings on both cylinders, so I think the problem is elsewhere.......

One last thing, no one has answered the question yet, was this a gradual thing or all of a sudden. Did it start doing this while running/working, or on start up one day?

normde2001 · Oct 5, 2006

Jagmandave said:
Well, erroneous or not, he said he got 300 psi on the front cyl and that's the one that causes the engine to die when he loosens the injector line, so it sounds to me like that's the one that's doing all the work and keeping the engine running, ergo his problen is with the other cylinder, right?

He also thought he was getting comparable readings on both cylinders, so I think the problem is elsewhere.......

One last thing, no one has answered the question yet, was this a gradual thing or all of a sudden. Did it start doing this while running/working, or on start up one day?

I re-read his post several times and don't see anything resembling what you are saying.

I see low readings on both cylinders, with no indication of which cylinder pegged the gauge at 300psi. (I don't believe you can be inaccurately high.)

pruntyc · Oct 5, 2006

I believe he said it was a rubber tipped one. So I'm not sure you can get a good reading on that high of compression, with it. Need a better tester. So he may have got one close with the 300 psi, on the one time, and not any of the others. I don't believe it gave that much just one time, and not any other time. So I don't believe he has got anymore information to work with, than before he did the test.

normde2001 · Oct 5, 2006

"At one point I pegged the gauge at 300 psi."

On second thought, if you can make both cylinders peg that gauge at 300psi, I would say your compression is not the problem.

kenmac · Oct 5, 2006

I would say that the 1 he got 300 lbs on is ok .I can't determine which 1 he says he got 300 from . You only got 2 cylinders so , the 1 that gives you less than 300 ( I would say ) is where wour problem is. Make sure tou are getting a good seal where the compression tester mates to the injector hole .

Tom_Veatch · Oct 5, 2006

Speaking out of my ignorance, I simply don't believe you can get good, repeatable pressure readings using a rubber tipped gauge on a small diesel.

First, the absolute pressures are high enough that some leakage past a hand held plug is a near certainty. Second, the volumes are small enough that a very small leakage will cause a very large change in the indicated pressure.

I personally don't believe the reading are repeatable enough to draw any conclusions.

JPFSR · Oct 5, 2006

I believe the compression readings are suspect probably because of the gauge.
I certainly agree with many of the earlier posts that the head has to come off to determine what's happening inside.
Wouldn't surprise me that he'll see some metal or at least some evidence of a failure.
Also a good idea to drain the engine oil to also look for some metal or at least to check its general condition.

JPFSR

garyd · Oct 5, 2006

Jagmandave
The problem began suddenly I beleive as I had not had this problem before. I was tilling with the tractor and a 48'' yanmar tiller as I have done many times in the past with no problems. The tractor bogged down and would not till. I drove it home with some bogging about 1/4 mile. the next morning I went out to see what the problem was and now here we are 3 months later no time no money you know how it goes. I dont know if that answers the ? or not.

bruce1966us · Oct 5, 2006

Sounds like a fuel problem (pump)

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.