I have a 1959 Massey ferguson 202 work bull (industrial version of a massey ferguson 35) that is misfiring on cylinder #4. The spark plug appears to be in good condition and I've tried others just to make sure but it hasn't made any difference. When I begin to pull the plug wire off the plug when the engine is running it begins firing on the missing cylinder when the end of the boot is about even with the end of the porcelain of the spark plug. I've tried replacing all the usual ignition components including plug wires, cap and rotor, points, and plug. None of this has made any difference. The engine runs great if I hold the plug wire just the right distance from the end of the plug. Does anyone have any idea what might be causing this or a possible solution? Any help would be much appreciated.
- Thread starter Holmanc
- Start date
Janicholson
Well-known Member
As Ben noted, a compression check is needed Look up how to do it, not hard but doing it correctly is the only way to use it
as a diagnostic.
If a new plug will not fire the #4 cylinder upon startup, the compression issue may be indicated. A stuck valve that looses
a pushrod can then close, or remain open and cause issues, but the v=firing with higher voltage ids not an indicator of that.
Jim
as a diagnostic.
If a new plug will not fire the #4 cylinder upon startup, the compression issue may be indicated. A stuck valve that looses
a pushrod can then close, or remain open and cause issues, but the v=firing with higher voltage ids not an indicator of that.
Jim
Steve@Advance
Well-known Member
That condition is almost always caused by a partially fouled plug.
If the cylinder has been run not firing, it may be really carboned and oily. As soon as the new plug fires a few times, it splashes up oil and soot, quickly fouling it.
You might benefit from a non fouler on that cylinder only. If that will get the cylinder firing, it may clean up after a while and the non fouler removed. Be sure the thermostat is in and working.
Also check the spark quality of that plug wire against the others. Check it at the plug end. Possibly there is a bad wire, points out of adjustment, worn distributor shaft bearing. Even though the ignition components are new, they are all aftermarket and the quality is just not what it used to be.
If the cylinder has been run not firing, it may be really carboned and oily. As soon as the new plug fires a few times, it splashes up oil and soot, quickly fouling it.
You might benefit from a non fouler on that cylinder only. If that will get the cylinder firing, it may clean up after a while and the non fouler removed. Be sure the thermostat is in and working.
Also check the spark quality of that plug wire against the others. Check it at the plug end. Possibly there is a bad wire, points out of adjustment, worn distributor shaft bearing. Even though the ignition components are new, they are all aftermarket and the quality is just not what it used to be.
rustred
Well-known Member
you could do the poor mans test then... hold your or finger over the hole and if it blows it off then it should have decent compression. if no or low it will not blow your finger off. agree its a fouled plug , they don't like to fire once oil soaked. increase the gap a bit.
ditchwitch
Well-known Member
How many volts do you have going to the distributor ? if its straight 12 volts it could be over heating the points and breaking down. I
think its only around 6 volts it needs going to the distributor. happen to me once is the reason i say that
think its only around 6 volts it needs going to the distributor. happen to me once is the reason i say that
The old trick used to be to cut the ignition lead & bare some copper & twist the end into a hole in a shirt button (4 hole type). Do the same with the plug cap end then twist that into a diagonal hole on the button. Put the cap on the plug & you now have an ignition lead with a gap the size of the diagonal spacing of the button holes. Vary the size of the button until you are happy with the "tune"!! Good luck!
Nomofingers
New User
I recently had this exact problem with my 65 and it ended up being an exhaust valve seat that dropped and wasn t letting the valve close all the way.
You've reinvented the "Spark Intensifier"!
There's been lots of threads on here over the years about them.
Link to a recent thread: https://forums.yesterdaystractors.com/viewtopic.php?t=1424558&highlight=intensifier
(In addition to the good advice you've gotten from others, a lean mixture in the cylinder in question or a "flat" camshaft lobe can cause a weak/hard to fire cylinder that fires with the aid of a "spark intensifier".)
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