md compression

sven · Nov 27, 2009

What is the minimum compression psi nessary for a farmall md. I am working on a tractor that does not fire on all cylinder until the engine gets real warm. The warm up period takes about ten minutes. In diesel operation the cylinders all show in the range of 160-180 psi. Is this too low, resulting in the long warm up period?

Janicholson · Nov 27, 2009

Yes. if measured in the injector hole. It should be much more than that. It cannot be measured in the spark plug hole in diesel mode (the third valve would be open, and reducing compression.) JimN

Peculiar Farmer · Nov 27, 2009

What is the temperature where you're trying to warm it up? If you have everything set correctly I've found that they start on gas rather quickly but they are cold natured and require several minutes of gas idle warm up even in 70 degree weather. Patience may be a virtue, but a necessity with MD's.

Andrew Z · Nov 27, 2009

i have the engine manual for my Super MD and it shows a compression of 556-614 at 1000 rpms, this would not be average cranking speed i think. i think the MD would be alittle lower compression but not to much.

Andrew

sven · Nov 27, 2009

It was measured from the injector hole. I guess this warrents a rebuild.

D Slater · Nov 27, 2009

Pressures IH gives are for a running engine checking one at a time. If you did them with one injector out at a time on the diesel side with the starter. It would turn to slow to tell much. If you had all injectors out and used the starter to check it sounds to low. Would check to make sure starting valves linkage is letting them close all the way. Check starting valves for sticking bent or bad since that can be done during tear down for the low compression if needed. Leaking injectors can cause the problem you mention also.

md compression

sven

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Janicholson

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Peculiar Farmer

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Andrew Z

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sven

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D Slater

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