IH 400 fouls spark plugs

super99 · Aug 16, 2014

My 400 has fouled the plugs every since I bought it. I put a set of non foulers on it and now it will run for a year or so on a set of plugs. I had to replace them again, so this time I ran a compression check on it. All 4 cylinders read 100 to 120#'s. Does that engine have valve seals that could be leaking oil into the cylinders? I figured the rings were wore out and that's why it fouled the plugs, but those readings should be good enough I think. Any ideas?? Thanks, Chris

Roger in Iowa · Aug 16, 2014

Does it smoke when running? Blue or black smoke?

casecollectorsc · Aug 16, 2014

Weak coil??

super99 · Aug 16, 2014

It will let out some black smoke once in a while, not all the time.

Fudd · Aug 16, 2014

What brand of plugs are you using? If they are Champions, throw them away. Go with Autolite or AC.

Anonymous-0 · Aug 16, 2014

Oil or fuel fouled?

notjustair · Aug 16, 2014

Look online and see what plug is recommended and go one hotter. Typically an engine that's fouling due to valve guide seals will smoke more when the engine is cold and also if you throttle it all the way up and then back down. The idle back down will draw more oil in (think car coasting up to a stoplight - if you see smoke then it is usually valve guides). You didn't mention it using oil. Sounds like it is running a little rich. Lean up the mixture and don't worry about it. Work it good and hard and it may help it out.

flying belgian · Aug 16, 2014

I agree with Fudd. Brand of plugs is the first place to start. Champion does not work in Farmalls. NGK is also a good one.

Steve@Advance · Aug 16, 2014

A couple of things to check...

As others said, be sure it has the correct plugs, might go one or 2 heat range hotter.

Is the thermostat working and the right temperature?

Is the air filter clean? If it has an oil bath, has the canister (the horse hair part) been removed and washed out?

Is the choke open fully, float level correct. carb working well? If all check out, try leaning the main jet, lean it until it looses power, then back it out just enough to run good.

Is the crankcase breather clean? Oil level correct (right length dip stick)? What is the carbon build up condition under the valve cover? Possible the drain holes are clogged causing the cover to fill with oil (extreme, but possible).

If all checks out, it just may be time for a rebuild.

pete 23 · Aug 16, 2014

Champion is all I put in IH engines. Have for over 55 years. It is the style, material and heat range that counts, not brand.

Bob · Aug 16, 2014

There's NO valve stem seals. But they can be installed if you research the dimensions involved AND the guides will accept them without machining.

Compression test is pretty meaningless for an oil-burner that runs well 'cuz and engine with good compression rings can have GREAT compression and still pump oil if there is an oil ring issue.

flying belgian · Aug 17, 2014

That is true Pete however, our local vo-tech built a testing cylinder with a glass site hole in it whereby they could keep increasing compression to see which brand spark plug would fail to spark first. Conclusion was Champion was the first to fail under increased compression. They are not saying spark failed completely but it became weaker before the others which in my opinion would lead to fouling plugs sooner. Incidentally NGK was best and Auto-lite was second best. I'm just saying.

Allan in NE · Aug 17, 2014

Comon' Pard,

You already know why it's pumping oil. :>)

Allan

farmerwithmutt · Aug 17, 2014

dad had an m the same way i went to a hotter plug no problem .one day the old man went to get plugs parts guy gave him plugs going by the book fouled out in an hour checked it out they were for an m working hard and this one had a loader on it

Anonymous-0 · Aug 17, 2014

Run the MD plugs I used them in my br deere it ended the fouling problem???

Blackhole49 · Aug 17, 2014

My snowmobiles fowl plugs by design. I can usually just wire wheel, re-gap and re-install several times before I replace.

C Kain · Aug 17, 2014

My thought was, 'get the champions out' !
Back in the 50's & 60's my dad had Farmalls
and had much better results with AC.

rustred · Aug 17, 2014

pretty much any engine not up to operating temp and working will foul plugs. idling around the yard is not the answer. plus what is the oil consumption on it? when they are in the field working they smarten up fast. plug brands don"t matter one bit.
does not have to be rings at fault for low compression. the valves must seal good. once the guides get worn the seats will be worn also and not seal properly. with new guides valve seals are not really necessary as that small amount of oil that goes into the guide is actually lubing them. you will not notice it in oil consumption.
you need to monitor oil consumption , for example if you work for 8 hrs and use 1/2 gal of oil then yes you need an o/h.
and any plug you use will foul up!

pete 23 · Aug 17, 2014

I don't doubt your findings at all. I would be interesting to know just what champion plugs were used as there are several different materials being used in the electrodes , plus protrusions of the nose along with extension of the outer electrode distance across the face of the center electrode. You will notice some applications the outer electrode only goes about half way across center electrode. Some people even modify that electrode for race cars etc I have been told. NGK uses a lot of precious (at least higher priced) metals in their plugs from what I understand.

T in NE · Aug 18, 2014

I suppose that"s why my 87 Dakota I had in high school quit eating plugs when I switched to an equivalent Autolite?

Yes, it burned oil. It only took once not getting hot, and the Champions fouled, never to be revived again. Ran the Autolites over a year with no problems.

Hobo,NC · Aug 19, 2014

I ran across this one time on a Farmall 140 it came to me with a set of plug anti foulers and would smoke a little... I had the hood off doing a 12V conversion and the valve cover leaked. While I had the cover off checked the valve adjustment and they were close to being tight.... Adjusted the valves took the foulers off and have never had a issue with the plugs since.... With the tight valves and foulers it was more of a very rich condition its cleared up now...

IH 400 fouls spark plugs

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