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.