IH 300u - Runs but Misses on a Cyl. What is it?

RTR · Jun 3, 2013

My uncle rescued an IH 300 utility the other day and the PO bought it to fix up. It hasn't ran in about 5-6 years and he didn't know much about tractors and didn't get it running. It was all there and complete except that the hoods were off. Upon getting it home we quickly got it started. It runs but misses badly on one cylinder. Compression is great across all cylinders. Noticed that there is a weld repair on the head near the cylinder that is missing. We are certain that is the problem but before we get another head and have it rebuilt I wanted to ask to see if there are any adjustments or special procedures for this type of engine. Maybe it is slightly out of time? My it is carburetor or governor needs an adjustment?. We haven't never worked on this engine before, just the small farmalls.

Just wanting some input and guidance. I can also take a video if it running and post it too.

D beatty · Jun 3, 2013

Before I would pull the head I would check the wire, plug and cap and rotor. If that head was cracked inside you should bubbles in radiator or oil flim in water and if its going the other way water in oil.

old · Jun 3, 2013

Trouble shooting 101 says check the spark at ALL 4 plug wires and make sure you have a good blue/white spark that jumps a 1/4 inch gap or more. Next take a propane torch or a can of carb cleaner and spray the intake manifold area around where it hook to the engine. If the RPM changes you have a vacuum leak and the gasket or manifold may need to be replaced. Also see by changing the plugs around if the miss goes with the plug

rustred · Jun 3, 2013

you answer ur own question, compression is great so no need to pull head. should post compression results. can be as simple as a dead plug so switch it with another one and see if problem follows plug. with wire core wires its unlikely to be a wire as i have 60 -70 year old wires working. only if the insulation is off it may be grounding out. being slightly out of time will not cause a miss.have a look in the cap terminals for green corrosion make sure the main load screw is turned out at least 3 turns up to 5 for heavy pulling. is the carburator clean? the most likely think is either a plug or a corroded wire. do a check with all plugs out. ground each plug to the block and have someone crank it over. should see and hear the spark snap on each plug.

Siefring Red Farmer · Jun 3, 2013

(quoted from post at 15:20:07 06/03/13) My uncle rescued an IH 300 utility the other day and the PO bought it to fix up. It hasn't ran in about 5-6 years and he didn't know much about tractors and didn't get it running. It was all there and complete except that the hoods were off. Upon getting it home we quickly got it started. It runs but misses badly on one cylinder. Compression is great across all cylinders. Noticed that there is a weld repair on the head near the cylinder that is missing. We are certain that is the problem but before we get another head and have it rebuilt I wanted to ask to see if there are any adjustments or special procedures for this type of engine. Maybe it is slightly out of time? My it is carburetor or governor needs an adjustment?. We haven't never worked on this engine before, just the small farmalls.

Just wanting some input and guidance. I can also take a video if it running and post it too.

I have 300 that did the same thing recently. Took the distributor cap off to find a bunch of rust fines in it that was preventing the lower lug from gettting proper spark.

todd hamilton · Jun 3, 2013

300s bad for ignition issues, put new points, plugs, condensor, cap on it and perhaps wires before doing anything else

Roger Tomfohrde · Jun 3, 2013

All good things to check but also check the push rods to make sure if they are opening the valves. I had a 404 that one was in the wrong place,did it when I got it years ago as the valve train was sticking. I didn"t see any comments about that if it sat for awhile.

IH 300u - Runs but Misses on a Cyl. What is it?

RTR

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D beatty

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old

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rustred

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Siefring Red Farmer

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todd hamilton

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Roger Tomfohrde

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