Farmall M miss on one cylinder, oil seeping from intake port

scruffyia

Member
Yesterday when I started the old 1947 M to pull some stakes out of the ground with the loader, it was running on 3 cylinders. I figured it was ignition related, and it's been a while since it's had a tune up, so I put new plugs, wires, and rotor on it. It's still not firing the 2nd cylinder from the back (3rd cylinder counting from the front)? I can pull the wire on/off that cylinders spark plug and the engine doesn't change it's tune at all. I pulled the plug wire off the plug in the head and put another spark plug in it, and it's sparking the plug perfectly. So I know I have fire in the cylinder, just no boom.

When I pull the plug after the engine has been running it's got unburnt oil on it.

Also on the manifold side, I see oil seeping from the bottom of the intake port?

I don't know how many hours this tractor has on it. I think the bottom end was rebuilt before i got it 15 years ago, but the head could of stood a rebuilt back then, and when i bought it I put a 3 point and loader on it and have used the heck out of it mowing, snow plowing, splitting wood, pulling posts, pulling wagons, trees when cutting wood, etc. But most the hours are mowing with a 6ft brush hog every year.

So I know it's past due to have some work done to the head. I just don't understand the oil seeping from the intake manifold port for that cylinder? That kinda concerns me? But maybe it doesn't matter if I need to rebuild the entire head anyway?

Has anyone seen this before? The exhaust/intake manifold is really old and brittle looking, so I thought that was why I dropped that cylinder, got a hole in it, but that doesn't explain the oil seepage or oil on the plug.

It smokes a very little while running under load, almost can't tell it if it is. When the governor kicks in it will send some smoke into the air while it digs down deep and revs up, but doesn't seem to use a tremendous amount of oil or anything. Odd it's leaking that much from the valve in the head (assuming that's where the oil is coming from)???

anyway, rambling... Please let me know your thoughts, and anything to look for, look out for, etc.

My wallet feels like it's going to hurt.

thanks,
mark
 
Quick check pull the tappet cover and check the valve clearence on that cycl while the cover is off make sure the valves in thaat cycl are moving also.
 
Think I would start by taking the valve cover off and look for a bent or broken push rod, or one off the rocker arm and or a stuck valve.
 
check the compression and your question is answered. without compression no way to burn the fuel in the cyl. and it is just slobbering it out. in short you need a head rebuild.
also when an engine dont sound right the first step is the compression check, that is #1 not just add parts.why skip the most important step that tells the engine condition.
 
I'll have to get a compression tester, I've misplaced mine, years ago... and see what I have.

I figured since it worked last week, and didn't yesterday, and I've been meaning to give it a tune up before winter so it starts better, I'd start with that, figuring one of the plugs or wires gave up since they were past being replaced.

It's probably time to bite the bullet anyway and rebuilt the head, finally get some unleaded valve guides in it, etc. The oil running/seeping out the bottom of the intake manifold port is really bothering me... something is worn out up there...

I didn't know if someone would know what that might be???

Heck, it might not even be related to the cylinder not firing, that could be a separate issue like the intake valve not opening because something broke. If something was stuck open, I'd expect backfiring if the exhaust was stuck open or messing up the other three's running if the intake was stuck open.

odd... but I guess I'm actually more concerned with the oil seep from the intake manifold than the cylinder not firing.

thanks,
mark
 
that oil is due to cyl. not firing as i suggested.you have a bad valve, no compression on that cyl. that cyl's valves has nothing to do with the other cyl's running. i am leaning to the burnt valve cause they cant be stuck if you say you use the tractor.
so check compression then tell us what u find.
also can hear a burnt exhaust valve, and thats the ones that burn first.
i would not even worry about the compression tester. just hold your thumb over hole while cranking cause there would be no compression to even blow it off. then you know its tear down time in a hurry.
 
I've thought it over and I'm going to have the head rebuilt. The amount of oil seeping out from the manifold/head gasket and running down the head isn't normal or "good". If that cylinder was firing, it would just be burning quite a bit more oil than it has been.

At one point today I cleaned off the seeped oil, replaced two plug wires, fired it up, shut it down, replaced the other two wires, fired it up, did some tests, then shut it down. In just that few minutes the oil had seeped out again and ran down to the cover below, an inch or two wide shiny seep.

The plug not firing I'd expect to be covered in gas (flooded), not covered in unburnt oil like I mentioned.

so whether it has compression or not, the head has issues and needs some TLC. and the reason for the cylinder not firing will be found as it's being torn down. with it leaking oil so easily out the manifold gasket, it's probably leaking air as well. The manifolds look brittle, so while it's torn down if they as brittle as they look, they'll be replaced as well.

Too bad it didn't do this last spring, it would have been a nice summer project...

thanks,
mark
 
well if you where messing with it how come u didnt check compression with the thumb method as i said? telling u what to do and your still guessing.diagnose the problem before teardown.
for all we know it may be the valve cover leaking and running down???
may have a broken piston and pumping oil out???
kind or annoying when you give the guy directions to find the problem and he comes back with another story, not attempting to find his problem he asked about.
as i said # 1 is compression check.
 
Came back with another story? What are you talking about? Adding the information about there being oil on the plug? Yeah, I forgot to mention that in my opening, I'm sure it's not the first time more information has surfaced as the problem is talked about... :roll: and your suggestion of sticking my finger in the plug hole was hours after I was done messing with it for the day...

Ok lets say it does NOT have compression, then what, tear it down right?

Ok lets say it does have compression, then what, tear it down right?

What scenario with the oil coating the spark plug and seeping from the head/intake manifold, is the head not coming off?

I said the head has needed work for a long long time, since i bought it 15 years ago, so why wouldn't I say, "after some thought I'm going to pull the head and have it rebuilt", rebuild it for unleaded gas, and whatever is causing the cylinder not to fire will be found along the way.

Sorry if that "annoys" you... feel free not to read or reply to my posts then.
 
I would not take the tappet cover off, Valve cover (as D Slater indicates) is a good place to start. Oil leaking on the outside means the manifold is leaking at that point. (probably the exhaust manifold. Jim
 
So what is keeping you from removing valve cover to see if the pushrods and rocker arms are moving as thats the first thing to do when you have one cycl not firing if theres fire at the plug. You ask for advise and the simple things you didnt do.
 
Since the tractor is not in front of us were just guessing. My guess is you may have a leak at the intake manifold opening. But don't think thats the complete problem. That runner feeds 2 cylinders, one is dead. If the cylinder in question is not firing or can't burn the fuel mixture for whatever reason, a mixture of unburnt fuel and some oil will be floating around since its not burnt to some degree and going out the exhaust. Probably like you see at the manifold.
If it was my tractor and I was sure the plug was firing, my next step would be to look at the upper valve train next. If everything looked to be working as it should, then I would check the compression. Then go from there as to head removal. Thats just my thinking, its not my tractor. I'm going to guess since it happend all at once that you have a valve operating problem or a broken valve if its firing at the correct time. Outside chance you may want to check the distributor cap for a crossover spark.
 
If I thought i could fix the oil problem, short of taking the head off, then I'd pull the valve cover and chase down why the cylinder won't fire. But I agree, the oil issue isn't likely causing the cylinder not to fire, there's a good probability something in the upper valve train is wrong and I could fix that and get it hitting on all 4 again without pulling the head.

However, this tractor is still used 100-200 hours a year, so the oil issue is something I want to get addressed and it's not likely something I can fix short of pulling the head. It's one of those things, while it's getting torn down to fix one thing, probably replacing parts, why not just take a step back and redue the whole thing so it's good to go for another few decades of work?

I'm too busy right now (and probably will be for years...) to tear the head off and everything myself and can have someone here not far away trailer it and get it done and back to me much quicker than I can do it myself. Yeah it's cost a lot more... But time verses money thing...

So yes, i could pull the muffler, hood, valve cover, etc, but in the end it'll get put back together and put on a trailer for the more extensive head work.

As I've said, the head needed rebuilt when i bought the tractor and just have never bit the bullet to do it. The bottom end of the engine is solid, probably time to fix up the top end up to match.

thanks,
mark
 
this is no different than a person going to doctor with ailment. doctor gives medicine to patient. patient then goes back without following doc's directions. doctor gets annoyed also.
even a lawyer goes by steps, not what if's
you must follow directions to get it fixed , not keep quessing.
its nice to see when guys fix the problem themself.
 
Like I said rustred to your last comment, what scenario exists for that much oil that doesn't involve pulling the head to fix it? It comes down to that.

Just like you said, no different than going to the doctor. If it requires surgery, I'll have that done and get it back much quicker because I don't have the time.

You didn't answer what scenario would leak that much oil from the intake port in the head that wouldn't require the head to come off, so I'll assume that means you don't have one.

thanks,
mark
 
had a SH not firing at all on #3 when I got it
oil soaked plug, oil seeping out at various places,
and the exhaust. good compression, puffing oil out #3
when test running with a hose in place of the plug
stuck my pinkie into the oilpan drain plug hole and
felt pieces....
pulling the pan revealed a broken piston skirt on #3
 
Yes, the head's almost certainly got to come off regardless of the problem, but for different reasons. There may be nothing wrong with the head. If you just blindly get the head rebuilt, and it turns out there's a hole in the piston causing the engine to pump oil, you've just wasted your time and $$$.

There is some information you can gather as to the nature of the problem by troubleshooting BEFORE you remove the head.

All he asked was that you put your thumb over the spark plug hole and bump the starter to see if you had any compression at all. You responded, "I'm not gonna bother, I'm just going to take the head off and send it out to be rebuilt." Very frustrating when someone comes to you for advice, you give it, and they blatantly tell you that they're not going to follow it.
 
No I didn't say I was just going to pull the head and send it off, blindly, without looking at anything else for the cause... please reread what I wrote?

I said that since the head has to come off, what is the problem will be revealed in that process. It will show if there's a hole in the piston, a broken rocker or push rod, etc.

The mechanic who will pull the head will look at the piston tops, sleeves, oil, etc for issues that could be causing the oil leak and problems.

I'm not sure why I have to defend making the decision to take the tractor to a mechanic?

I'm not sure why I have diagnose and narrow down what it could be, when the motors going to be cracked open and it will be apparent?

If there was just one thing going on, the dropping of the cylinder, i'd greatly appreciate the help in diagnosing the miss.

But since it's more than that, and i know the head is worn out from decades of use, and the head needs to come off to fix the oil issue, I said i decided to have a mechanic work on it since i don't have the time to do it and don't want to be without it for as long as it would take me squeezing in a few minutes here and there to work on it.

Sorry I came to that conclusion and that it annoys all of you.

I'm sorry that the head is worn out and that it needs to come off to fix the oil issue.

Really, I wish all I had was a "miss" issue to resolve...

Maybe a moderator can just delete this thread, since I've decided the direction i'm taking doesn't need further assistance and it's just annoying you and wasting your time.

I was premature in posting a question, I should have thought through it a while longer. sorry for wasting your time.

Thanks for those that have responded with helpful information, sorry I'm not going to dig into deeper and wasted your time.

thanks,
mark
 
ooh is that so? stop assuming.i answered that right off the bat. didnt you read where i said broken piston.your assumptions dont make sense either. your making a big deal out of that wet manifold like its just drowning in oil which is not the case as the pic shows. when you ever get compression checked and tell us then can go to next step. ... my scenario is when you have compression with the head rebuilt that my cure the oil leak your talking about. even just working the tractor in the field under load can cure that ,,, kinda. i have saw lots of these old tractors slober just puttsing around yard with no load and never reach operating temp.
so happy compression checking, as i said reading plugs and compression check tell the story so why assume.
 

so a broken piston is your scenario where the head doesn't have to come off to fix it the oil leak???

Thanks for you time.

later,
mark
 
NO ITS NOT!check your compresion for the forth time.do you know how or understand compression readings, no one here can give you more advise till thats done.
forget it your lost on this engine and do not even understand what i am telling you. you just want to argue and not follow direction.
 
Sounds like a valve stuck open for whatever reason on that one cylinder.
Broken spring atc. The amount of oil shown seeping is not serious, possibly a worn guide, that would also cause it to stick. If it were a damaged piston you would hear the air exchange into the crankcase on the compression stroke.
 
You can redo the head if you like,but if you dont give it a new set of piston rings while your there,,# 3 is gonna continue to drink oil.Nuff Said
 

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