Dead Cylinder #3

garmartin

New User
Dead cylinder #3! I have been around Ford N tractors my whole life and in the last 7 years during my retirement, I have started buying nonrunning N tractors to fix up and sell just as a hobby. I have come across a 9N that is driving me crazy. The initial problem was a stuck open exhaust valve on #3. Was able to use Pblaster and transmission fluid to free it up and is working fine except, the cylinder is still dead. Originally there was 0 compression but after unsticking the valve, it now has 95psi. The other cylinders vary between 95 and 105psi. Checked for spark and it seemed week so I replaced the distributor and points. Cylinder #3 still dead. When I pull off the spark plug wire on #3 while running there is no difference. The new 437 sparkplug in cylinder #3 still looks brand new and does not get hot to the touch while the tractor is running. Thinking there was a manifold problem, I removed the manifold and inspected for a problem but found nothing wrong. While the manifold was off I inspected the valves but found nothing wrong. I took a piece of paper and held up to intake on block and turned engine over to see if there was suction to manifold and carburetor and there was. Put manifold back on with new gasket but cylinder #3 still dead! What am I missing?
 
I should point out that when I put on the new distributor and points, I also installed 437 spark plugs and new wires.
 
garmartin,You say new distributor and wires but don;t mention cap or rotor. Cap could be bad.Also swap @3 and @4 plugs around and wires.

This post was edited by Den N Ms on 08/06/2021 at 08:17 pm.
 
(quoted from post at 23:11:01 08/06/21) garmartin,You say new distributor and wires but don;t mention cap or rotor. Cap could be bad.Also swap @3 and @4 plugs around and wires.

This post was edited by Den N Ms on 08/06/2021 at 08:17 pm.

Yes, new rotor and cap, new points and condenser. Plugs from cylinders 3 and 4 were swapped, plug wires also swapped with no change.
 

Assuming you now have a strong spark to # 3, I would pull the plug and add at least a tablespoon of fuel into the cylinder and then quickly replace the plug and give her a whirl. If its a fuel problem it should momentarily fire up in that # 3 cylinder.

If you have a strong spark and good enough compression I guess I would be sure fuel is getting into the cylinder.
 
Long shot, but maybe the bushings in the distributor shaft are worn enough that
it's flopping around a bit, enough to make a spark, but maybe also enough to delay
the sparks timing...?

Ben
 
Are you certain that when you swapped plugs that it was still #3 cylinder that was missing and not #4? You could easily have gotten a shorted plug. Maybe put one of the old plugs into cylinder #3.
 
That's really odd. Grab a cup of coffee and another well seasoned gear head and start over again with the basics. The firing order is 1243, the dizzy turns CCW. Check your spark on each cylinder, etc. I'm assuming the points in the dizzy are set right, the advance mechanism is not bound up on anything IE too long of a screw and the distributor cam actually has 4 distinct humps that set the points to the appropriate gap to fire off the coil. Do a spark check both when cranking and with the engine running. Perhaps the points are bouncing off the cam at higher rpm and the number 3 is the cylinder it's doing it on. If all of that is in order and it's still misfiring then....

This is unlikely but possible that the valve is sticking/weak spring at anything over cranking speed. Provided your compression gauge is rated for this you'll want to get the compression of said cylinder at say 1000 rpms vs the rest of the engine. The valve I would expect to stick in this instance would be the number 3 exhaust if one is sticking.

Given it supposedly runs on the number 4 I would assume the manifold and gasket is AOK. I would also make sure that cylinder pressure isn't ending up in the radiator while running. Again while this is something odd I wonder if a partially failed headgasket would cause this. Long shot but I would check.

Good luck, you'll have to let us all know what you find.
 
pull side cover off when running so it can be watched. Had one that would stick open kept prying closed and putting oil on stem , finally cleaned up.
 
(quoted from post at 11:24:45 08/07/21) Are you certain that when you swapped plugs that it was still #3 cylinder that was missing and not #4? You could easily have gotten a shorted plug. Maybe put one of the old plugs into cylinder #3.

Nope, #3 didn't work. First used new 216 plugs and then switched to 437 plugs hoping that would fix it but nope.
 

Some good ideas to check. I have been leaning on maybe the head gasket. Just want to eliminate all the "easy" stuff before removing head. When I put the manifold back on, I used new gaskets. I will check the distributor again even though it is a new one because this is obviously something preventing the cylinder from firing as the new 437 plug looks totally new. I didn't notice any moisture on it but will check that again. One thing I thought was unusual, when I had the manifold off and was turning over the motor with starter, there seemed to be exhaust coming out of all 4 exhaust head holes in order, 1-2-4-3.
 
(quoted from post at 10:45:29 08/07/21)
Some good ideas to check. I have been leaning on maybe the head gasket. Just want to eliminate all the "easy" stuff before removing head. When I put the manifold back on, I used new gaskets. I will check the distributor again even though it is a new one because this is obviously something preventing the cylinder from firing as the new 437 plug looks totally new. I didn't notice any moisture on it but will check that again. One thing I thought was unusual, when I had the manifold off and was turning over the motor with starter, there seemed to be exhaust coming out of all 4 exhaust head holes in order, 1-2-4-3.
re you absolutely sure it's firing the number 3??? Have you used something like a spark checker https://www.lislecorp.com/specialty-tools/tune-up/coil-on-plug-spark-tester to make sure you have spark while the engine is running?
 
(quoted from post at 14:03:13 08/07/21)
(quoted from post at 10:45:29 08/07/21)
Some good ideas to check. I have been leaning on maybe the head gasket. Just want to eliminate all the "easy" stuff before removing head. When I put the manifold back on, I used new gaskets. I will check the distributor again even though it is a new one because this is obviously something preventing the cylinder from firing as the new 437 plug looks totally new. I didn't notice any moisture on it but will check that again. One thing I thought was unusual, when I had the manifold off and was turning over the motor with starter, there seemed to be exhaust coming out of all 4 exhaust head holes in order, 1-2-4-3.
re you absolutely sure it's firing the number 3??? Have you used something like a spark checker https://www.lislecorp.com/specialty-tools/tune-up/coil-on-plug-spark-tester to make sure you have spark while the engine is running?

I have not checked ked for spark on #3 while running but I will. Good idea.
 
When you pull the plug from Cyl #3 is it wet or perfectly clean? If you have a timing light clip it on the #3 wire and see if you get a flash showing spark.
 
(quoted from post at 08:56:22 08/08/21) When you pull the plug from Cyl #3 is it wet or perfectly clean? If you have a timing light clip it on the #3 wire and see if you get a flash showing spark.

He has stated the plug was clean and not wet, thus my suggestion to squirt some fuel in it and see if an application of fuel would shed some light on the situation. Everyone is stuck on spark. He says he has spark and it is also very easy to check as you suggest.

I would also think that exhaust valve could be slow to close under running conditions giving him no or little compression.
 
So, pull the plug, attach it's plug wire and ground out the base of the plug to the block. Easiest way to know if the spark has made it all the way to, ~~and all the way through~~, the plug and is presenting itself to the cylinder.

I would check the entire system all the way to the suspected problem spark point first (of course checking the plug's gap), and if there is a problem, like no spark or weak spark, THEN work backwards, systematically troubleshooting 'upstream' to the source of the problem.

If there is spark through the plug then squirt a little fuel in the plug hole, hand tighten the plug, reattach the wire and see if it fires. IF no luck then a simple compression check is in order before going deeper into the valves, piston and rings.

- Joe -

This post was edited by Joe.S.AK on 09/06/2021 at 06:06 am.
 

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