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Cylinder only fires with plug wire partially off?

T

tractorsam

Well-known Member
I am trying to resurrect an old Case W-3 backhoe with a G159(I think) gas engine. One piece at a time I?m making progress. It has been running on only 3 cylinders and number 4 was pumping oil into the exhaust manifold. I adjusted the valves earlier today and #4 was way off. I then discovered that by pulling the plug wire almost all the way off (just #4) that it will fire and run as it should. I did put a set of plugs (Autolite 386?s) in it when I got it running and maybe I need to put another in #4 but are there any other ?get me by? solutions I can do to keep it running until I can give it the overhaul I expect it really needs? Many thanks.
 

Try swapping the plug wires to verify if the problem travels ?
Could try the non resistor 3116 Autolite . Plug gap ? Coolant temperature ?
 


Go through and renew the ignition system. Check the distributor for wear, sometimes they will wear enough so the rotor does not to have close enough contact with the cap. If the plug wires are shot (maybe they are the originals!), replace them. Make sure the gap on the problem plug is the same as the others. All simple stuff.
 
Pulling the wire off a bit, dramatically raises the resistance between the coil output and ground. As a coil discharges, voltage increases when resistance increases,,,,, you are making the coil put out much higher voltage. And this higher voltage is enough to properly make the plug fire. SO>>>>> this usually means the spark plug is either fouled up, partially open/ separated inside the ceramic, or has some other defect. Either way, it means the plug is not firing normally, sometimes even due to high compression, as high compression requires a better plug, to fire correctly. Usually... a new plug will fix this. Usually... If plug is fouling out due to oil or other, a new plug will quickly foul again as well. I have also seen this happen where a head gasket was leaking moisture into the cyl, and the increase spark would make the plug fire correctly or enough to fire off the cyl... again making a "fouled plug" fire. Either way, your raising the voltage to fix a problem or various problems.
 
An old "sparky" here would make a little thing out of a non conductive material, which would go onto the end of a spark plug, and hold the end of the wire a distance[maybe 1/4"?] away from the spark plug. The spark jumping that gap would keep the plug from fouling. I've seen something like that available, but don't remember where.

Dad did this with his tired AC WD, before he had the engine rebuilt. This would have been in the 60's. A WD45 took over as the "big" tractor, and the WD got an M&W engine kit. It's still going, without a hiccup!
 
Bingo, Bill.

Not uncommon.

Sounds like the OP needs plugs and/or wires but not a coil.

Dean
 
Hello tractorsam,

Shorted plug! Swap that one to onother cylinder, bet you it will miss there untill you pull the wire lime before,

Guido.
 
(quoted from post at 11:27:14 01/26/20) Bingo, Bill.

Not uncommon.

Sounds like the OP needs plugs and/or wires but not a coil.

Dean
Click to expand...
Back in the teens and twenties there were many plugs made that had a built in spark gap to do that same thing.
 
The company is still in business. The Aldor 'smart plug'. Made in East Farmingdale, Long Island,NewYork.Aldor is named after the inventor,an old farmer named Albert Doering in the early 1920s..They work.
 
plug is fouled takes more juice to make it fire,, like said below pulling wire away increases voltage as long as you have a good Blue spark,,
 
if its passing oil and fouling the plug, there is an old school solution. go to napa and get an anti fouling cap for the spark plug. take a plug with you to get the right size. here is a link to what you are looking for
poke here
 
One old-timer trick was to cut the high tension wire (this only works with wire core wires-- not carbon core) and cut away the insulation- baring about a inch on both ends. They would then find a button of the proper size and thread the wire ends through the two button holes across from each other-- now twist up the wires so they hold onto the button. What this does is holds the wires apart about the right distance for a make shift "spark gap". Of course the button needs to be made from some thing that is a insulator. Back in those days there were many devices sold that clamed to "intensify" the spark --- what they were was some device that incorporated a spark gap
 
That plug id either bad or fouled. I do not buy auto lite or champs any more since they tend to be bad right out of the box. I use NGK plugs now days
 
Indeed, Glennster.

Anti Foul adapters.

They do work.

NAPA should be able to order them for you.

Dean
 
Take a piece of baling wire make a small loop or such to hold the wire on then wrap the other end around the porcelain with the gap about a quarter inch away it will fire. Cheap and easy. It causes the voltage to jump the gap to increase. They work well and if the plug goes to missing from it just plug the wire on the plug till it misses again.
 
I guess I am old then as i seen a few made with both a boughten extender and ones made with #9 wire doing the same thing, every time it was on engines that pumped oil and would foul plugs with this change,, I never seen the ones from teens or twenty's though this was in the mid 60's
 
That old remove the plug wire a bit makes them fire has been around as long as I remember. Its often due to a plug that's fouled and when voltage across the gap starts to rise there's a small current flow via the fouling path (oil or carbon etc) that bleeds off the energy so it never reaches the high firing voltage necessary to arc jump current across the gap as intended.

A fresh set of plug and/or wires if needed can help but that's a band aid approach to fix the underlying problem causing the plugs deposits (oil or carbon) and subsequent fouling be it due to over rich operation or its an oil burner.

John T
 

You could phart around with half baked farmer fixes . Or replace the old worn plug wires with new solid core wires . Make sure the coil is wired to the same polarity as the battery . Otherwise the coil s output will be limited if backwards .
Plug gap with non resistor wires and non resistor 3116 at plugs 30 thou.
If the coolant temp is not kept at 195F or more , the plugs will foul and no wonder widget quicky fixes addressing the symptoms. Will be satisfactory. Quicky fixes will not solve the cause .
Straight weight 40 oil will burn less than 15W-40.
 
Like others said, no easy fix for oil pumping.

But in the mean time, look the ignition system over carefully, check the distributor shaft bushings for wear, check the points condition and gap, check the centrifugal advance.

Be sure you are getting a blue hot 1/4" spark at each plug end, not just at the cap.

Check the air filter. If it has an oil bath filter, there is a wire mesh above he oil bowl that needs periodic cleaning, often overlooked.

Be sure the crank case vent is clean.

If the carb is not right, go through it. Especially if it is flooding. The carb will only work as well as the rest of the engine, and only if it is fed clean gas. Adjust the mixture carefully, especially the high speed mix. Too rich will promote plug fouling too.

Be sure the thermostat is working and at least a 180*, 195* if it will handle it.

Go with the hottest plug range that will fit. If it still fouls the one plug (and it may do better now that the valves are adjusted and other problems addressed) install an anti fouler only on the one that is fouling. If it begins to misfire on that cylinder again, look at the plug. If it is blistered or melted, drop down to a colder plug on the one with the anti fouler. The anti fouler protects the plug from splashing oil, but also insulates it from the heat transfer of the head, resulting in a much hotter running plug.
 
Thank you to all who replied. I agree that there are a lot of things I need to do to this machine for it to be correct and in good working order. I could write a very long list of all the issues that this machine has and in time they will all get sorted but right now I?m fighting fires and trying to improve (not necessarily permanently fix) them.

I have no history of this machine, it landed here not running and every time I run it I fix a couple of things and find another dozen or so that need fixing. I?m not sure if the cylinder is pumping oil because it wasn?t firing on that cylinder or if it quit firing because of the oil. I?m hoping that if I keep it firing long enough it might stop pumping oil.

Right now it has suppression wires on it (look quite new) and I?ll replace them when they make it to the top of the list. I?ll get a new plug for that cylinder and if a couple of new plugs don?t do the trick I?ll try an anti-fouler. Now for the leaking steering cylinder, engine oil leak, dirty gas tank, hydraulic lines with holes, loose front bolster.... ;)
 

sparktester.jpg
 
Dad made the same ting, using a piece of plastic measuring stick and an old spark plug, to get the center post and nut of the old plug,...drilling two holes in the plastic about a half inch apart.
 
The old timers in my neighborhood used to cut the spark plug wire in a convenient location, strip some insulation off of the cut ends and tie the stripped ends into the thread holes of a common shirt button, leaving a gap between the thread holes. The spark would arc across the gap and make a fouling plug fire better. They'd put on a neat light show after dark. Fascinating to a kid.

These tractors that I saw this "fix" used on usually had a dripping sediment bowl nearby.

Hobo has a fix that wouldn't destroy an otherwise good spark plug wire.
 

Not my contraption, I worked on a worn out Farmall 140 he had them on all the spark plugs he said he had ran it that way for years... I had to take a pix I doubt I could live with it that way are at least for long...

It would make a good diagnostic tool tho :idea:
 
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