300 compression

CNKS · Mar 17, 2015

I have a 300U with the 169 cu in engine. The factory compression is 145. My dry compression is 110 with one cylinder 105, wet they are all 120, meaning there is some ring wear. If this was a letter series tractor with its factory compression of 125 or so, I wouldn't think much about it. However, with the compression of 145 how much wear does this engine have? It runs ok. I did forget to open the throttle if it makes any difference--will check it again tomorrow. I bought the tractor a couple of years ago to "restore" it, I overhauled the engines of the other tractors if the compression was off in one or more cylinders, this one does not have that problem.

kub6040 · Mar 17, 2015

Does it smoke or have low oil pressure , it is a little low but can still run well if there are no issues .

Wayne in MN · Mar 17, 2015

Charge your battery and then re-test with open throttle and all plugs out. Compare to first set of numbers. Second test should read higher.
Do you need more power or just want to make the tractor run its best as is?

Janicholson · Mar 18, 2015

I would also recommend checking your compression tester against a known standard of accuracy. I have one Snap-On that is within 1# of a liquid filled gauge I trust. My other gauge is less accurate "2#" or so, but easier to use. Jim

CNKS · Mar 18, 2015

Thanks, I think mine is ok unless it was defective when I bought it, used maybe a half dozen times.

rustred · Mar 18, 2015

(quoted from post at 18:37:20 03/17/15) I have a 300U with the 169 cu in engine. The factory compression is 145. My dry compression is 110 with one cylinder 105, wet they are all 120, meaning there is some ring wear. If this was a letter series tractor with its factory compression of 125 or so, I wouldn't think much about it. However, with the compression of 145 how much wear does this engine have? It runs ok. I did forget to open the throttle if it makes any difference--will check it again tomorrow. I bought the tractor a couple of years ago to "restore" it, I overhauled the engines of the other tractors if the compression was off in one or more cylinders, this one does not have that problem.

its also good to know the oil consumption of an engine , as using a quart or 2 in 100 hrs. i would not overhaul it yet if compression is decent.

300 compression

CNKS

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kub6040

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Wayne in MN

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Janicholson

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CNKS

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rustred

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