Spark plug fouling

[rrlund]

I can't say I'm at wits end, that happened a couple of years ago. I've got an Oliver 1600 gas that keeps fouling the spark plug in number 6. I use it for a short time twice a day to feed round bales. A new plug will last from 3 to 12 days. They're just wet with gas, no sludge like oil fouling. I've tried drying them out with a torch, leaving them for weeks, they can't ever be re used. A new plug is all that ever fixes it.

My son thought it might be the carb flooding it out. We took it apart and put it in his ultrasound outfit on Friday about three weeks ago. The next day, I ground two loads of feed with it to work it hard. I fed round bales with it on Sunday. Monday morning,it started alright, but was missing before I even made it out the the tool shed. I've gone through 4 plugs since, usually just letting it miss for several days out of disgust and frustration.

When I change a plug and it's running right, it still seems to me that it has a slight swish when it's running. If one of the rockers was too tight on number 6, COULD that cause what's going on? I've been wracking my brain trying to figure out how. Maybe an exhaust valve sucking air on the intake stroke so the gas was just pouring in wet instead of vaporizing? When I run it a few days with a fouled plug, it'll be wet around the plug and will be running right down the side of the engine on the manifold side. I'm probably all wet myself on my rocker too tight theory, but I'm throwing things at the wall to see if anything sticks. With the loader in the way, it won't be overly simple to take the tappet cover off, and I don't want to risk ruining the gasket if there's no way in creation that it could be the problem.

 

[Bob Harvey]

Randy. I'll guess an intake valve stem not sealing. HTH

 

[John in Mich]

I'm not familiar with the Oliver 1600 (I'm a Ford N guy) BUT, my experiences with fouled plugs mirror some of your trouble. First, I would want to know current compression readings as compared to original specs.
Second, I would verify timing. Third, install new hotter range plugs. Forth, with the engine properly warmed up, I would set carb as lean as I can but still not stumble when I smack the throttle to wide open. That may take several tries. AND fifth, most importantly, I never do short runs on the engine. The low led gas will foul cold plugs (cold engine) quickly. It sounds to me that your #6 cylinder never gets up to a good operating temperature.
Others may chime in with information relative to the 1600 or their personal experiences.

 

[Royse]

Not a fix, but a stop gap might be an antifouler under the sparkplug.

 

[504]

Move two plug wires around to see if it is a resistance problem. No change go two heat ranges hotter on that spark plug.

 

[Janicholson]

I also suspect fowling down in the center insulator that is hard to see. While it is running (and fouled on that cylinder) pull the spark plug wire about 1/4 inch away from the plug if it picks right up and runs on that cylinder, the answer is fowled, not adjustment. I would try a hotter plug by two heat ranges. it is a temporary cure. were it mine and I found that to be the case, I would put a set of valve seals (or umbrellas) on the valve stems. Jim

 

[Jaden]

Possibility of an ignition problem such as marginal plug wire, etc.?

 

[NY 986]

My sometimes foggy memory says that the head has seals for the valves. Maybe the seal on number 6 is getting poor. I bought a set of seals for the 88 and need to do that job someday.

 

[NY 986]

I should note based on what I have been told a seal can weep enough to allow oil by but yet not show classic oil saturation signs.

 

[Hobo,NC]

Did Oliver use those new never have to adjust valves. All jokes aside if it has solid lifters I would have to check valve adjustment. Everything you say it pointing toward it and with a strange issue cold I'm looking up the valve adjustment specs.

 

[rustred]

Important and to know the compression on that cylinder for sure. Hard to make a call without it. I would presume u have checked the spark at the plug with it out. Yes it can be a tight valve. Check compression and a valve set, if you find a tight one recheck compression after the setting.

 

[Steve@Advance]

Yes, do run the valve lash, just to say you did!

While you have the cover off check the valve train over, look for broken springs, check for excessively worn guides, especially on #6. If it's carboned up, scrape and vacuum it out. If it's really clogged, oil may be pooling around the back cylinder valve guides faster than it can run back down.

But I suspect it is suffering from short runs, not getting up to temperature long enough to burn the oil out of the cylinders. I've seen this before where an engine is run with a non firing cylinder, it gets gooped up with oil and as soon as it starts firing it splashes oil on the new plug and fouls it. Things can go from bad to worse running it that way when the rings get carboned up to the point of sticking in the ring groves and the oil drain slots get clogged.

I would try running a non fouler on that cylinder for a while, see if that will get it firing and maybe clean it up so it won't have to stay on there forever.

I assume it has a working 180 or 190 thermostat.

Good hot spark at the plug end of the wire?

 

[Cash4Toys]

Randy, you say the plug is wet from gas, no oil fouling. Would that not eliminate valve seals?
You also say it is wet around the plug, and runs down the side of the engine. Must have fairly decent compression to do that.
I would look harder at the ignition system, cap, rotor, condensor and wiring. Could very well be intermittent spark to that cylinder.

 

[redforlife]

Try a different plug wire. Swap it out with another one on the same tractor if wire lengths will allow, and see if the missing and fouling moves to a different cylinder. If problem moves, it's a bad wire.

There is a chance that it might be the wire, or perhaps that terminal is bad in the distributor cap (as in a crack, or a bad post inside). But if you can rule those out, my next guess would be bad compression due to a bad valve or tight clearance on a rocker. It could have low compression on that cylinder. If so, it'd be pulling in on the intake, and then not compressing it. With no compression (or low compression) the plug could possibly be sparking but not igniting that cylinder due to lack of compression.

As for leaking gas out that spark plug (through the threads), IT SHOULD NOT be doing that. Have you had spark plugs in and out that hole so many times, that the threads in the head for that spark plug are bad??? And now you can only get a plug to fit in there snug, but not tight enough to hold compression. If you do a compression test, and it's bad, there might lie your issue instead of bad valves. I guess you'll have to rule that out yourself. But a spark plug should not be leaking compression so gas can run down the side of the engine. It should be blowing all of that out the exhaust valve, even if either of the valves are bad. Not through the spark plug threads.

 

[crsutton81]

I had a JD once that did somewhat similar. It would always be the same plug gas fouled in fairly quick order. Like you, a new plug would temporarily fix it for about 45 minutes...if you ran the snot out of it. Got to looking and the rocker arm shaft had a very slight crack underneath that allowed the valves to change clearances for that cylinder when warmed up, as it was on the end of the shaft, hence the last cylinder in the block since it was past the last mounting anchor point to the head. A new shaft cured the problem.

 

[Geo-TH,In]

Do a compression test. You need good compression to get gas to burn properly.
Eliminate spark plug wire.

Instead of buying new plugs, Try rotating the #6 plug with #5 plug and see if #5 cylinder can clean up the plug.
Bad valves will not compress the air and during cold times bad compression doesn't warm the air enough to get a good burn..

 

[rrlund]

I had a full set of those antifoulers in a 350 Farmall. It was the only way I could keep that tractor running. That was a bad oil
burner. I mentioned them to Jeff at the auto parts store and he said they don't carry them anymore. I didn't ask if he could get
them, but I guess I'll have to.

Some mentioned swapping some wires. Tried that too. Five is on the opposite side of the cap and the same length, I swapped them and
it fouled a brand new plug in 6 as soon as I started it up.

 

[Dave BN]

I was going to say what redforlife wrote in his 3rd paragraph. You can check everything everyone else has suggested as all are good ideas but no way you should see raw gas leaking around the spark plug.
Dave

 

[PJH]

I made an adapter out of an old spark plug and a pipe fitting so I could hook up an air chuck and pressurise a suspect cylinder. Sometimes it will point you to a leaking valve, headgasket or a ring issue before removing any parts.

 

[dhermesc]

Agreed - I would start with a compression test. Much of the advice you are getting here are for dealing with an oil fouled plug - not a fuel fouled plug. Good chance it's a valve issue - but with the unburnt fuel you may have scoring issues with the piston and rings now.

 

[rrlund]

It kind of shoots my theory of a compression or intake leak though. If it has enough compression to push that unburned gas around the threads and copper gasket on the plug, it must have some pretty good compression. I don't know. My son will be here for dinner tomorrow, I'll hash out some things with him.

I've been running AC R44 plugs in it. I bought a hand full of Champion 508 at Farm and Home Monday and put one of those in. I don't know if they're any hotter or not.

 

[JMOR]

(quoted from post at 10:23:16 11/23/22) It kind of shoots my theory of a compression or intake leak though. If it has enough compression to push that unburned gas around the threads and copper gasket on the plug, it must have some pretty good compression. I don't know. My son will be here for dinner tomorrow, I'll hash out some things with him.

I've been running AC R44 plugs in it. I bought a hand full of Champion 508 at Farm and Home Monday and put one of those in. I don't know if they're any hotter or not.

it must have some pretty good compression." You do know that combustion pressure on power stroke is a 'bit' higher than compression pressure.

 

[Cash4Toys]

I do. But, if it is not firing, hence the
wet plug, how does it have combustion
pressure?

 

[redforlife]

Stop and think about it. The other cylinders have good enough compression to fire cylinders and not foul plugs, and not a one of them leak gas out the spark plug threads. But your dead cylinder in question does, and your thinking that is a good thing?? That it's doing that? Blowing air/gas out the spark plug threads is not in any way normal, and does not entail that there is no issue with compression. And definately not a good thing. And, no, it doesn't add up to eliminating compression as a problem. The other cylinders not doing that, proves that it shouldn't do that, it's not normal, and it is a problem and not a good thing.

A gas and air mixture enters the cylinder upon intake stroke. If that mixture is not fired, it is blown out the exhaust upon exhaust stroke. Even if valves are bad, it will do that anyways with a very high percentage of the gas and air mixture. Since it blows basically all of this out the exhaust regardless, it doesn't really build up liquid gas inside the cylinder, other than enough to make things wet. It doesn't pull in a mixture, and then shoot out nothing but air. What is blown out, is also a mixture on a non-firing cylinder. But it will retain enough gas in there to make things appear wet, such as your spark plug on the non-firing cylinder.

Liquid won't compress. Thats how hydraulics work. If you had a cylinder plum full of gas, it should be bending the rod, and not forcing it out the plug threads. If you had bad valves or rings, it should blow it through there, or be bending the rod before forcing it out through threads. Even if it did build up some liquid gas in there while running, it wouldn't build up enough to hydrau-lock given the 1 in the 10 to 1 (or what ever) compression that you have. It wouldn't build up enough liquid gas in there to surpass the 1. Even if it did, the extra liquid gas added to one cylinder stroke, wouldn't be enough to cause what you say is going on.

 

[gene bender]

with the wire hooked to the plug removed do you have spark maybe just a bad wire

 

[rrlund]

It doesn't blow it out if it's firing. Everything will dry up. If I let it miss for days at a time after it starts missing, then yes, everything gets wet. I'm sure it would do the same thing if a pulled a wire off any other cylinder and ran it that way. Not saying for a minute that it's a good thing, but if was an open valve from a rocker too tight, seems like it would be more likely to just be pushing it out the manifold wouldn't it?

 

[rrlund]

Like I told Royse, I swapped 5 and 6 and it didn't help. Cap is fairly new, points and rotor were new about July when it was giving me trouble unloading hay.

 

[ErnieD]

Check the distributor cam lobe for your problem.
Find someone with a vintage SUN ignition scope.

 

[redforlife]

Well, technically yes. If a valve is stuck open because of no rocker clearance, then there be no compression because of no air tight cylinder.

But, .... say the cylinder will fire at 70 psi compression. But not at 45 psi. And yours is at 55. Enough for the cylinder to fire SOME with an un-fouled bran new spark plug. But not, once fouled by wet gas because of not firing all the time because of inadequate compression.
Then the dead cylinder never fires, because of not only bad compression, but also a fouled plug. At this point, there still should not be any leakage at plug threads NO MATTER what the compression is. The leakage only indicates one thing. That it should not have any leakage. And leakage can only be coming from bad threads in the head, or on the plug. Being a new plug, unlikely to be bad threads on a new plug.

For what it's worth, it shouldn't be doing that. And I'd wager a bet, that your other cylinders WOULD NOT do that if you ran the tractor with the plug wire completely off of any one of them you were doing the test to. And if they somehow ironically all did the same thing, then obviously someone has put in an entire set of the wrong plugs at some point.
Shouldn't be no leakage. Leakage indicates bad threads or wrong plug, no matter how you slice it.

 

[rustred]

This is something I have seen before , only because the plugs are not torqued enough. That plug gasket is what does the sealing. I am sticking with low compression not firing the plug, but we should have had a response already.

 

[rustred]

Check the Compression before tearing the cover off. Diagnose first. Then attack