H Compression Ratio readings

c1802362 · Nov 2, 2012

Checked my '41 H's compression numbers tonight.

Cold cranking yielded the following (gauge readings in psi)

Cyl 1: 90
Cyl 2: 93
Cyl 3: 88
Cyl 4: 85

Does anyone have any opinion as to if this is normal or low?

The tractor's S/N ends in X3, which I understand is distillate, but
I've been running it for years on gas

Art

Janicholson · Nov 2, 2012

That is just about perfect. Of course higher is better, but that is about all that can be expected from an engine that can run on distillate tractor fuel. The readings are close enough to each other to be acceptable, and not an issue. Running it on gasoline is correct. There is no distillate available. Jim

gene bender · Nov 3, 2012

Nothing wrong with those readings but you wont know what pistons are there until you remove the headcause without a doubt the old distillate ones are not there anymore use and enjoy.

The Red · Nov 3, 2012

I believe the distillate compression ratio was 4 to 1 so that would be very good. Straight gas is 6 to 1.

c1802362 · Nov 3, 2012

thanks everyone,

the reason I'm looking into the engine is that it runs fine the first hour, then starts smoking in the second hour. (for example, I took the neighborhood kids up and down the road for Halloween. We were out for about 2 hours. The cycle was to pull the loaded haywagon - about 35 kids and adults - under full power to a house, idle for a few minutes while the kids got their treats, then repeat.)

When I pull the plugs, there's a slight bit of oil/moisture on the plug tips.

Sounds like I may want to pull the head and replace the head gasket, as well as look at the head

randy hall · Nov 3, 2012

x3 is for kerosene which has a lower compression ratio than distillate.

Janicholson · Nov 3, 2012

The head is probably not the issue. The compression is good, so head work will not give results. First would be oil. I would put synthetic 15W-40 oil in it. The synthetic is more stable at temperature, It is also probably thicker at operating temps, and thinner at cold start than 30 wt. If that 40.00 change does not assist this worn engine, Sleeves, pistons and rings (about 750 if you do it) will make it operate well, and have the advantage of higher compression pistons, and bigger bore. Changing the head to a higher compression Gasoline head would also add hp. jIM

rustred · Nov 3, 2012

have you checked the oil bath air cleaner? i have seen many of these tractors for some reason with rain entering the oil container. use a 10-30 oil in it when servicing it.make sure not over full. i have also seen the rain water frozen and tractor would not even start.

c1802362 · Nov 3, 2012

the oil bath air cleaner gets looked at about every three months - its clear

c1802362 · Nov 3, 2012

I've been running straight 30 weight oil since I bought the H some 10 years ago. The multi viscosity oils may very well solve the problem

I'm getting ready to change the oil anyway, so this may be a relatively inexpensive test

David G · Nov 4, 2012

I run 15W-40 Delvac in mine year round. It smoked a little on straight 30, does not at all now. I got the tractor from my dad third hand, so have no idea on the wear.

kossuth · Nov 4, 2012

Might be worn valve guides. Wouldn't show up in your compression numbers but you would have oil "slobber" build up on both the intake and exhaust valve ports of the head where the manifold bolts to. Those motors from the factory didn't have valve seals so it's possible it's alittle worn.

PretendFarmer · Nov 6, 2012

X2 on that. Dont rebuild the lower end. Waste of money. If anything, do the head over.

H Compression Ratio readings

c1802362

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Janicholson

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gene bender

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The Red

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c1802362

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randy hall

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Janicholson

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rustred

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c1802362

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c1802362

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David G

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kossuth

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PretendFarmer

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