Farmall 100 missing cylinders

DW Swindall · Apr 24, 2011

My 100 started missing on the 2 back cylinders. Replaced the plugs, wires, dist. cap, checked the adjustment on valves. It has about 95 lbs of compression on all 4. I am at a loss. The only thing I can come up with is maybe the head gasket. There is no water in the oil. Any one have any idea what can be causing this. Thanks in advance. It happened while I was plowing. Just all of a sudden.

Nebraska Cowman · Apr 24, 2011

The first thing I would check is to see if I had spark at those cylinders.

gene bender · Apr 24, 2011

Stop and think you have compression so the gasket must be ok. By changing the plous from cycl to cycl then the wires then the cap you will get it figured out sometimes it takes a while jusst work on one cycl at a time. I would get a wire that has the metal end at the plug so you can ground it out when running to see if the fire is getting to the plug this could help real fast.

Jg20601 · Apr 24, 2011

My 140 started missing under load after I had replaced the plugs and wires. Saw the answer one night with the tractor running, the spark would run on the outside of the wires and jump to ground under load.

With the compression even, the head gasket should be ok.

old · Apr 24, 2011

Always a mistake to throw parts at a problem before you know the reason for the problem. Always check things like spark on ALL cylinders and do things like move plugs around from non-firing cylinder to firing ones so as to know why you have the miss. A problem like that one could be things like distributor shaft bushings or an intake manifold problem or plug wires etc

CharlieNJ · Apr 24, 2011

DW, how is the gasket under the intake/exhaust manifold near those back two cylinders?

DW Swindall · Apr 24, 2011

Don't know about the gasket at this time. That will be something to check out tomorrow. Thanks for the input.

DW Swindall · Apr 24, 2011

Did check all that stuff. It needed all the things I replaced even if it wasn't misfireing. All plugs are firing. It just seems to not be getting gas to those two. Thanks

DW Swindall · Apr 24, 2011

JG, that is what I was thinking about the gasket. The compression was almost identical on all cylinders. I completely overhauled about 4 years ago and has not really been used that much.

DW Swindall · Apr 24, 2011

gene, that is almost exactly what I have done. I just seemed to hit a stump. I was told to pull the wires off the 2 that are fireing and put a little gas in the cylinders that aren't, then put the plugs back in and turn it over to see if they fire. If they do then they are not getting gas. (Sounds reasonable to me)

DW Swindall · Apr 24, 2011

That was the first thing I did was check to see if I had fire. It would jump about a half inch or more.

DW Swindall · Apr 24, 2011

Hey thanks for all the input. Now I have some other ideas to work on. I had rather any of my tractors go down but not this one. I will let you guys know what I find when I find it. I know as smart as all of us are we can fix it. (HA)

old · Apr 24, 2011

You may also have a problem with the intake/exhaust manifold some are known to go bad by way of a hole rusting into them between the intake and exhaust and if that happens you loose what ever cylinder that hole goes to

DW Swindall · Apr 24, 2011

old to old, I am afraid you may be right. I found a hole in the exhust side of the manifold. I did spray starter fluid all around with the motor running and there was no change in tone of the motor. That will be the second thing I do after putting some gas in those cylinders to see if it act like they want to fire. Thanks

old · Apr 24, 2011

Ya finding a hole between the exhaust and intake can be hard to do and about the only way to find it is if it is where you can see it if you remove it form the engine and even then a lot of times it is where it can not be seen and has to be pressure checked to find it

El Toro · Apr 24, 2011

Check the lobes on your distributor to make sure they're not worn and see if there's a lot of slop in your shaft when you wiggle it. Did you install a new rotor? Hal

John M · Apr 24, 2011

Pull the valve cover and see if the rockers are opening the valves. Slight chance, but it may have broke the cam.

rustcollector · Apr 24, 2011

DW

Just out of curiosity, was the tractor running on all four before the "tune-up"? Fireing order 1-3-4-2 and not 1-4-3-2?

Tom Fleming · Apr 24, 2011

If you have good compression on all 4 cylinders, you don't have a gasket, ring, or valve issues. It is spark or fuel.

What do the plugs look like in the 2 cylinders that are not firing? fouled or dry and clean?

Janicholson · Apr 24, 2011

What I can imagine is that the engine started to misfire. You took it home and changed the components listed. By accident you replaced the plug wires in the order they appear on the block, but that order is from front to back, as read 1342, not using the rear of the engine as #1. It is clockwise at the cap from the 1:30 position clockwise, #1 then #3 then #4, then #2.
#1 is at the front (radiator end). Jim

El Toro · Apr 25, 2011

As Jim stated you need to check your plug wires to make sure they're in this firing order on your cap with No1 cylinder near the radiator. Hal

2-1
4-3 as the rotor rotates CW. Check Nos 3 & 4 to make sure they're not reversed.

Farmall 100 missing cylinders

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