Spark plug questions

wallacedw · Nov 23, 2008

I hope the picture is good enough to see.
Looking at the picture you see the rearward plug (no.1) at the left and forward plug at the right (No.4) (as you look at the left side of the engine). One plug was a different kind completely.
The tractor has been acting seriously fuel starved. It won't run smoothly, very jerky, and doesn't seem to be going to full power. I can't figure out what I did to make it happen. I don't think I put any ethanol in it. I cleaned the fuel bowl, drained a bit from the bottom of the tank itself, replaced an inline fuel filter, and changed the oil. I also took the distributor cap off and sanded the rust off the rotor. This helped a little but not much.

I haven't figured it out. As far as the plugs. I read that a plug looking like the one on the left, with its deposits and all, is a sign it could be burning oil. So would that mean that cylinder is bad? What should I be thinking about when I look at these plugs? It ran great when I bought it a couple months ago.

RobMD · Nov 23, 2008

Engine looks good, might be a little bit lower compression on the rear cylinder.

Replace the plugs, wires, dist cap, points and condenser.

What was done to the carb? could have plugged passageway making for erratic vaporization.

jose bagge · Nov 23, 2008

given the odd-ball plug, you have no real idea as to when these were installed or even if this is the only vehicle they were installed in. I'd swap in a fresh set, run it for a long while and see what happens. None of those plugs look ferociously bad...frankly, I'd be suspicious of the cylinder with the odd plug in it. Why? When?

John T · Nov 23, 2008

Wallace, generally speaking, a flat black colored smooth sooty coating is excess unburned gas while an uneven shinier wet black looking deposit is an oil burner. That cylinder may have low compression,,,,,,,,,,burned/leaky valve,,,,,,broken piston ring,,,,,,Id run a compression check on it. Id also replace the plug wire to that plug and if theres any doubt whatsoever as far as the distributor cap (for that terminal) Id replace it. A good general tune up of points n condensor and cap and rotor and wires wouldnt hurt as its not all that expensive and a set of fresh MATCHED plugs.

John T

caterpillar guy · Nov 23, 2008

Get rid of the inline filter and it will be fine.

james rumph · Nov 23, 2008

There is alot of things listed by fellow readers that should be checked and done.

"But" loose the inline filter, these tractors were designed to run on gravity feed.

Fuel filters were designed with fuel presure in mind. I have even trien atv fuel filters but they won't flow enough.

Sounds like a good tune up is over do.

Anonymous-0 · Nov 23, 2008

have you checked to see if all plugs are suited to that motor?

Anonymous-0 · Nov 23, 2008

Wallace,
First get a set of NEW and MATCHED plugs, Get rid of the in
line filter, then give us a problem. All engines I know of #1 is
the front cylinder EXCEPT G Allis. "It ran great when i bought it",
means I personally would REVERSE whatever I FIXED and see
where I went wrong. A tune up set (plugs,wires, points,
condenser, cap and rotor) will probably cost less than $50.

noncompos · Nov 23, 2008

You said you had rust on the rotor; while I've never seen that, it could mean the tractor was sitting for quite awhile. But, as suggested, an ign kit, cap, wires and plugs seem called for, if you're not just flat broke.
Generally speaking, if you have corrosion on the rotor contact you also need to look at the plug wire contacts on the INSIDE of the cap; chances are they'll be corroded and need cleaning too.
Check the spring or carbon contact on the top of the rotor, and its contact INSIDE the cap. THEN check where the coil and plug wires go in the cap; shine a light in, and if not bright clean them. Corrosion/decay in any of those places can cause weak spark (resulting in dirty plugs)and misfiring.

wallacedw · Nov 23, 2008

Great responses, thanks!!

I did put fresh Champion D21's in. I replaced the inline filter that was there when I bought the tractor. I will take it off and see what happens. I haven't done anything to/with the carberator yet. The tractor had sat most of the time except to move hay once in awhile in the winter. The rotor was corroded o the top and the end. The contacts in the cap aren't corroded at all. There is nothing that goes from the top of the rotor to the middle wire of the cap.Thats got me a bit confused.
Really the only thing that i did before it started acting funny is replace that inline filter. I will get that out and report back...

Why would that one plug have so much junk? It was a D21. There are so much deposits that it cant have been giving much spark. Do deposits like that burn off (if they are built up inside the motor)?

Anonymous-0 · Nov 24, 2008

What makes you think that maybe some Ethanol mite have been added and would have caused a problem. We have been using it for over 25yrs without any problems. I use the Fram see thru inline filters on a couple of my tractors as the gas tanks arent quite up to being super clean without problems and have used them for yrs. When they get plugged you just install a new one as thats what they are for is to collect dirt.

Anonymous-0 · Nov 24, 2008

D21 is a hot plug.Do a compression check,if the engine is pumping oil the plugs will foul often.I alway chuckle when I see clean the rotor and distributor contacts.The spark voltage can jump a 1/2 gap on most tractors when the engine is running.Changing all the ignition parts with out finding the bad part is a waste of money.If the new plugs say made in Mexico on the box you have introduced a new problem to the mix.No amount of ignition tinkering will fix oil fouled plugs.Look up Aldor spark plugs on the web.

wallacedw · Nov 24, 2008

Ethanol does cad things to rubber. I had to replace the needle valve in my old Dodge because the rubber disintegrated. Evreything I read pointed to the ethanol. The 'flex fuel' vehicles are designed with no rubber internals and most modern tractors don't have the rubber inside. Thats were I got that from. I know it is supposed to be a good thing but I dont trust it in my stuff. I would rather pay the extra 30 cents a gallon. Guess I am like my Grampa... hard to change.

ScottyHOMeY · Nov 24, 2008

Somebody mentioned it down below -- you don't say what the tractor is but, in most cases, #1 is at the front of the tractor, nearest the radiator, and #4 at the rear, just the opposite of what you describe. Is it possible you've got your firing order wrong at the cap?

wallacedw · Nov 24, 2008

Huh... thought I put the tractor type in. Oops.
It is a Massey Harris 44. When I was talking about cylinder no's and plug numbers I was referring to the order of the plugs in the picture. I wasn't sure how to describe the tractors firing order. Now I do! Thanks..
I never messed with plug wires so I think I will start with getting rid of the inline fuel filter first.
I am trying figure out why the plugs might be fouled up like they are. Some ok, some cruddy..

olgentdc · Nov 24, 2008

Someone mentioned the points ,,, All my SC Cases have given me fits such as this. The manifolds were burned thru !. Any Chance the Exhaust and intake are sharing Gases like ALL MY SCs did until I fixed them ? ...

wallacedw · Nov 24, 2008

How would you check for that?

Anonymous-0 · Nov 24, 2008

Find some AC or Autolite and ditch the Champion plugs and you will find it runs longer before fouling the plugs.

Gerald J.

buickanddeere · Nov 24, 2008

What coolant temp was the engine running at?

wallacedw · Dec 12, 2008

Changed the points, condenser, and cap and she runs like a charm now!

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