Diagnosing source of smoke on H farmall

A

Aggie Farmer

New member
I’ve got an H running that was sitting for a long time. It runs but smokes and fouls plugs. I ran a compression test and all cylinders were uniformly around 90 psi or above. Is it possible to have ok compression but stuck rings ?

Of course I know valves could be an issue also. First time I’ve ever done this. I hooked a gauge to the manifold vacuum port. The needle is holding steady in range but fluctuating rapidly 2-3 tick marks. After reading my diagnostic cheat sheet, it says valves are the problem.
 
I assume your compression was a dry test. You could try a wet test by squirting a little oil in the cylinders and see if the pressure readings go up. If yes, add some sea foam to the gas per manufacturer recommendations and run it hard for a while to see if the smoke clears up a little.
Also you didn’t mention the shape of the ignition system. Points, plugs and timing may need some attention. Good luck.
 
Bill V in Md said:
I assume your compression was a dry test. You could try a wet test by squirting a little oil in the cylinders and see if the pressure readings go up. If yes, add some sea foam to the gas per manufacturer recommendations and run it hard for a while to see if the smoke clears up a little.
Also you didn’t mention the shape of the ignition system. Points, plugs and timing may need some attention. Good luck.
Click to expand...
Points, condenser, plugs, rotary cap, plug wires, etc… are all new. Timing is perfect. I did a wet and dry test. Here are the numbers.
 

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Those readings are well above 90 psig, but looks like the rings could be stuck. I would try some Seafoam. You can add it to the gas tank and the crankcase oil. By the way, what color is the smoke?
 
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My 47 H had been sitting for nearly 20 years since I got it running again. It was stuck, not bad as it was fairly easy to break free. It was smoking pretty good (cylinder 3, I believe). Rings were stuck and there was some light pitting in the sleeve. Compression test revealed 85 psi in that cylinder, didn't do a leak-down test. What worked for me is I got the engine hot, squirted some Marvel Mystery Oil in that cylinder a few times and then worked it hard. The smoke didn't completely go away, but it is significantly less. It is on the list for an overhaul someday soon.
 
Your compression test indicates either worn or stuck piston rings. However, I would suggest adjusting the valves since you probably have no idea if they are within spec or not.
The plug fouling may be caused by engine oil getting past the rings due to the conditions mentioned above.
 
pull it hard for a half day,---get it hot and see if that helps any. If not then its a motor rebuild
 
Have you tried running some SeaFoam thru it? My Cub acted like it had a stuck ring when I bought it, SeaFoam in the oil and the gas helped tremendously. Just make sure the exhaust is above your face or the wind is at your back, don't ask!

John
 
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