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Should I Rebuild?

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westdogtown
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Tractors Owned: 1975 International Cub
1952 Farmall Super C
1999 John Deere 5210

Should I Rebuild?

Postby westdogtown » Mon Dec 25, 2017 10:12 pm

I have a 1975 Cub which I use for gardening and growing sweet corn. It seems to have enough power but smokes a lot out of the crankcase breather/oil filler cap and some from tailpipe. Smokes even more under load. Don't have to add that much oil and doesn't foul spark plugs. In fact they look pretty clean. Oil pressure is good. Compression is around 110 or so on all cylinders except one which came on up when a little oil was added to cylinder. Engine is not making any unusual noises and starts easily. What do you guys think? Would you re-ring it or just keep on using it and not worry about the smoke?

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Eugene
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Re: Should I Rebuild?

Postby Eugene » Mon Dec 25, 2017 10:24 pm

Tough question to answer. I have a Cub that has 105 PSI, dry compression test, dead cold engine, blows some smoke. Does what I need the tractor to do. Not going to rebuild the engine.

What I would do is check the valve/lifter gap and put some Sea Foam in the engine oil and gasoline. Compression problem may clear up, may not.

And then, if you decide to overhaul the engine - - - - funds and time consideration.
I have an excuse. CRS.

Jim Becker
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Re: Should I Rebuild?

Postby Jim Becker » Mon Dec 25, 2017 11:00 pm

What was the dry compression on the 4th cylinder?
Have you cleaned the crankcase vent tube that goes from the front of the engine block to the air cleaner (if there is one)?

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Stevetractor
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Re: Should I Rebuild?

Postby Stevetractor » Tue Dec 26, 2017 6:39 am

Had a 68 I was getting ready to put to work last winter and had the same symptoms you describe. Don’t use it to mow with so felt engine maybe still had some life in it. Did cold compression test and found a cylinders fairly even at 100-110 psi.
Try pouring a quarter cup of sea foam directly in cylinders and let it soak down around rings. If you can let it soak for a week or so, the better. Every time you walk by, rock crank back and forth slightly by turning fan. I try to make sure pistons are at mid stroke in cylinders before adding sea foam. It really works well to dissolve all the carbon around the rings that keep them sealing as well to the walls of the cylinder. After it soaks as long as you can allow, add half a can directly to oil and run tractor an hour or two and change oil and filter. I like to use 15-40 rottella t plus a pint of Lucas oil stabilizer. It’s very tacky and helps to seal worn rings. Hope this helps and good luck.

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Re: Should I Rebuild?

Postby Boss Hog » Tue Dec 26, 2017 7:14 am

That low cylinder may be the problem, if you have been using the tractor on a regular basis nothing in a can will help it .
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Power corrupts; absolute power corrupts absolutely byJohn Emerich Edward Dalberg

inairam
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Re: Should I Rebuild?

Postby inairam » Tue Dec 26, 2017 8:40 am

A wet compression test does indicate rings. If you have good oil pressure and good compression of 3 of the 4 cylinders and your are not noticing a big loose in power, I would try a few thing before a complete rebuild

I would try some "hope in a can" only because it is hope.

I will say my 49 was doing the same thing with one low cylinder low and an increase in the compression with oil and smoke out the oil fill tube and exhaust and low power. I cleaned the vent tube, had the head & valves machined and adjusted the valves very carefully and it gave me 100-105 psi on all cylinders.

There was a lot of carbon built up on the head and piston tops plus the head was leaking a little. So a top end rebuild helped me but your issue could be more serious. I still would try "hope in a can" and adjust the valves and cleaning the vent before you commit to pulling the head and or doing a complete rebuild
When you only have 9 horsepower you need to know the names of all of the ponies!

jsfarmall
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Re: Should I Rebuild?

Postby jsfarmall » Tue Dec 26, 2017 10:18 am

If it's doing what you want then it's totally up to you. A set of rings is probably all you need. Doubtful machine work is needed. If you had the parts sitting there you can re ring it and have her running that afternoon and never split the tractor. Real easy to do. I ordered parts for my 48 with a full gasket set which does cost a little more than you would need, 160 dollars and I had the engine together. Head gasket set and oil pan gasket would really be all you would have to get. Exhaust manifold gasket might come with the head gasket set. Not sure.
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westdogtown
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Tractors Owned: 1975 International Cub
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Re: Should I Rebuild?

Postby westdogtown » Tue Dec 26, 2017 8:22 pm

Thanks to all of you guys for your comments. I am going to try the things you suggested first before a re-ring job especially checking the valve adjustment.To answer the question about the cylinder with low compression, I think it was around 90 psi before adding oil and yes I have cleaned the oil breather cap/vent. Thanks again.

jsfarmall
5+ Years
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Posts: 605
Joined: Sat Oct 22, 2016 1:04 pm
Zip Code: 72454
Tractors Owned: 1948 Cub "Trusty"
1948 Cub "Rusty"
1948 Cub "Bob"
1948 Cub "Sallie" (wife's tractor)
1965 IH Cub "Annie"
1943 Farmall H
1953 Farmall Super M (granddad's tractor)

Re: Should I Rebuild?

Postby jsfarmall » Tue Dec 26, 2017 11:38 pm

Simple things are always best to try first.
1948 Cub "Trusty"
1948 Cub "Rusty" mower tractor, trimmed ear dash
1948 Cub "Bob"
1948 Cub "Sallie"
1965 IH Cub "Annie" mower tractor,
1943 Farmall H,
1953 Farmall Super M

Jim Becker
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Re: Should I Rebuild?

Postby Jim Becker » Wed Dec 27, 2017 12:33 am

90 # isn't that bad. Do the adjustments and treatments suggested and run it.

The vent tube I was asking about is the small diameter tube that connects to the air cleaner (assuming your tractor has one).


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