Farmall H running rough

Harv42H · Jan 4, 2015

Here is a picture of the plugs I removed from my H. The plugs are new with just a few hours of running. From left to right is 1,2,3,4 cylinder plugs tractor missing real bad. Looks like #2 is the only plug firing or getting fuel . 1 ring is sitting on the towel

T.R.K. · Jan 4, 2015

It looks to me like your misfire problem is on #2. The rest are clean like they are burning properly. To doublecheck, put them back in, put one of the others in #2. Try killing cylinders 1 by one. If #2 does not cause rpm drop like the others its your problem.

A Valve problem-not sealing or bad valve/seat, or a short in distribuitor cap or plug wire can cause that.

Janicholson · Jan 4, 2015

If it is running on one cylinder it would just sound like a single cylinder lawn mower idling. Putt putt putt. Running rough means irregular firing making variable speed and little power.
With it running, pull off one plug wire at a time (with insulated plug wire pliers). This allows diagnosis of which cylinders are working. If no change the cylinder is not working. If it dies, or slows down radically it is working.
The #2 plug seems to have oil fouling on it. the others look about right for today's fuel, and a few hours of run time. The next step is to assure the point gap is correct, the timing is good, and the mixture is rich enough. If these are good, and the issue persists, check the compression. adjust the valves, and get back to us. Jim

D beatty · Jan 4, 2015

I go along with number 2 not fireing. First thing check cap and wire to that plug. You might try a differant plug its not impossibility for a new plug to be bad.

D beatty · Jan 4, 2015

After looking at picture closer 2 & 4 look like they aren't firing. I would check wires first than cap and then plugs. Was the tractor running smooth before the new plugs?

IA Roy · Jan 4, 2015

I would also check to see if the plug wires are on the correct plugs. it would probably run if 2 were reversed, but very poorly.

bill mart · Jan 4, 2015

right side up?

Cory Schmidt · Jan 4, 2015

The dirty plug is most likely the problem. The rest are working fine if clean and dry(more so if new). Sounds like the same problem that is happening on the W4 here, same engine(as H) same cylinder as well(#2). Had new points, condenser and so forth a year or two ago. When it gets bad a change of plugs, just that one helps some: works for a while anyway. Not getting around to get it in shop to look at. My guess is valve someplace is not right (sticking, not adjusted, busted)

notjustair · Jan 4, 2015

I agree with everyone - you are thinking backwards. Number two isn't firing the rest are. Don't quote me, but I would just about bet you couldn't get the old girl to start on only one cylinder. Two would be questionable. Switch out that plug. It may have gone bad. I had the exact thing happen yesterday on a Ferd.

schumy ia · Jan 4, 2015

if you pull the plug wires off one at a time to find the miss. do it at the distributor. you will seldom get a shock this way. My favorite way is to use a infrared thermometer on the exhaust manifold to see which cylinder is cold.if you think it might be a plug or wire, switch them to another cylinder before you spend money on new ones.sometimes the distributor cam can be worn uneven and cause a miss on one cylinder.always check the simple stuff first, saves alot of money

Wheatfarmer · Jan 4, 2015

An old trick was to take your firing order, and move the last half of numbers under the first half. the engine should run (But poorly) on the two cyl of the numbers in each column. If it doesn't run one of those cyl is bad. Never tried it on a 4 cyl engine.

jimg.allentown · Jan 5, 2015

What was the question???
If I were you.....even though I am not.....this is how I would proceed....
Start with a compression test. Follow that with a check of the ignition system.
Fuel CANNOT cause a single cylinder to miss under any circumstance that I know of. The carburetor simply mixes the fuel and air and the mixture is taken into the engine by atmospheric pressure. Carburetor problems generally affect ALL cylinders similarly. The one exception being in the case of vacuum leaks. In this case, I suggest that you check for leaks around the intake manifold gasket.
Keep in mind that it is much less expensive to diagnose the problem first, and replace parts afterward. Good luck.

Harv42H · Jan 25, 2015

I did a cylinder compression test and three were at 90psi and #four was at 80 psi. Still can hear a miss at both low and high idle, have not had a chance to drive it lately , but three out of the four plug have turned the black dry sooty color. Thank You all for taking time to help.

Farmall H running rough

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