Case engine miss

Hello,

I bought a Case 410 (gasoline) tractor a few years ago, used for odd jobs around the yard. It was in reasonable shape, but required a bit of maintenance. One of the things I did was change the spark plugs, and spark plug wires.

Everything was OK for a while, and then I started noticing a “miss” in the engine. Tracked down the missing cylinder, exchanged the plug with one from another cylinder, the miss moved with the plug. So I replaced the plug, and all was well (for a little while).

Then the miss returned, so tracked down the offending cylinder again. This time I pulled the wire at the plug to see what sort of a spark I was getting. I held it about ¼ of an inch from the plug, looked like a decent spark, but much to my amazement, the engine smoothed right out, the miss was gone! As soon as I touched the wire directly to the plug, the miss returned. I repeated this a number of times to confirm that this was really happening.

So far, no one I’ve talked to has been able to come up with any suggestions as to why this is happening - I hope someone on this forum will be able to help me.

Btw, I’m using Champion D16 plugs, I’ve been told these are the correct plugs for this tractor.

Thank you,

Regards,

Dave

I've had similar problems with this brand of spark plug recently.
Some folks have surmised that these products can be inconsistent
due to sloppy manufacturing in overseas factories, but I have
seen no direct and personal proof of that. All I know is that when
I replaced them with Autolites, my problems disappeared. You
might also check your wires to make sure they are sound and that
the ends are tight. You can add some dielectric grease for
moisture control, too.

DAve

First, get rid of those plugs.... Champion plugs are junk. Replace them with Autolite 386 or Autolite 3116 plugs, and then start the troubleshooting again. I'm a bit puzzled by your statement that the tractor runs smooth on 3 cylinders, but my bet is on the plug being the cause of the roughness experienced when the fourth plug wire is connected..

We installed three different sets of Champions in the past couple of years because they are all our local supplier kept in stock. All three sets either had bad plugs out of the box, or they failed within a few hours. In all cases, we replaced them with Autolite plugs and the problems when away.

like the others have said.Get rid of those Champion plugs. Ive had nothing but trouble from them. I also use Autolite plugs or AC.Also , alder tractors run better on solid plug wires. Go to TSC or simular farm store and they are about $12 for a set.

Fouled plug. A D-16 used to be the right plug, but 89 octane gas with lead and no alcohol used to be the right gas. The AC and Autolite plugs everyone is saying are sooo great are extended tip plugs. I ues D-18Y and have no trouble.The reason it stops skipping when you pull the wire off is because the double gap you are creating. Instead of shorting through the fouling it goes back to jumping the gap.

Holding the wire close to the plug increases resistance in the circuit that is overcome by a higher voltage coil discharge producting a stronger spark.

It is the same thing as "auxiliary gap" plugs that are used to help prevent fouling, especially is commercial applications. Champion sells a "one tug plug" claims easier starting for small engines. On the back of the package is a plug pic showing the gap in the center electrode.

I agree with lose the Champs. Autolite much better in my experience.

Joe

Hello,

Thank you to all, it seems everyone is in agreement that the problem is with the plugs. I'm a bit surprised, I was under the (un-informed) opinion that Champion was the "cadillac" of the spark plugs.

Any way, I'll certainly change the plugs as suggested, and I'll let you know how I made out.

Thanks again,

Regards,

Dave

(quoted from post at 04:55:21 09/05/11) DAve

I'm a bit puzzled by your statement that the tractor runs smooth on 3 cylinders, but my bet is on the plug being the cause of the roughness experienced when the fourth plug wire is connected..

Click to expand...

Joe, just to clarify, the tractor started firing on the bad cylinder when the I held the wire about ¼ of an inch from the plug, and had to jump the gap. So at that time, it was running on 4 cylinders.

regards,

Dave

By holding the plug wire the 1/4" out from the plug, you're in effect, creating a larger gap than the one on the plug. The collapsing magnetic field in the secondary winding has to build up more voltage to complete the circuit. It may go from 20,000v to 30,000v for example. Enough to fire the faulty/fouled plug. The main reason to change plugs, even on newer engines. The increased voltage requirements of well used plugs overheats, or stresses, all ignition components

Hello,

Thought you might be interested in a followup.

Well, none of the recommended AC or Autolite plugs seemed to be available at the various suppliers, so I decided go with Klyde’s suggestion, and try the D-18Y plugs (which weren’t in stock, of course, had to be ordered).

I changed out the plugs yesterday, started up the tractor in anticipation of everything working well. My “bench-mark” test is raising the bucket on the front-end loader - if there’s any mis-firing, this extra load always makes it very apparent, almost causing the engine to die. You can imagine my disappointment when there seemed to be no change. I rechecked everything, making sure I had reconnected the plugs in correct firing order, everything looked Ok.

So I started it up again, was about to lift the bucket, when the engine started sputtering, then died completely. Out of gas (duh)!!

Added a couple of gallons of gas, started it up, what a difference ! Now when I raise the bucket, or climb a slope, no more missing, the engine responds smoothly to the extra load. I’ll feel more confident after I’ve run it for a time, but it looks like the new plugs did the trick.

Thank you so much to all of you for your help.

Regards,

Dave