A burping 8N

I sought help a few weeks ago regarding my sick sounding '49 8n. Yesterday the weather was nice enough to work outside and trouble shoot. I covered off on all the easy potentials...drain gas, checked plugs, checked plug wires, etc. I paused and just listened to the sickness and soon realized this tractor was "burping" air out of the air intake as well as muffler. Upon further investigation, I noted that the air breather tube (from carb to cleaner)seemed hotter than what a breather tube should be. I pulled a rookie mistake and took off oil bath cup and when she burped oil spit out from cleaner and caught on fire for a second when oil hot muffler!

What would cause exhaust (I assume) to be be forced back up through the breather tube. A few other points to maybe help a kind member diagnose..

1. No exhaust smoke comes through the air filter. When it burped with cup off oil did come out but no exhaust.
2. Not too long ago I reattched the muffler to the manifold...could I have created a blockage?
3.I checked the spark plug wires and as far as can tell they are all connected right?
4. Gas is good.
5. Oil batch cup was filthy...did not realize if could get this cruddy.
6. There was no change in how it ran with oil cup on or off (I did not think there would be) but I almost lit tractor on fire doing it!

Guys, I would appreciate any guidance. I am not a complete rookie...having restored another 8n from top to bottom, but this particular 8n has me totally confused....
 
Sticking valve could cause it to backfire through the carb. If intake hangs open on exhaust stroke some of the gases will back into the carb.

Any critters build a nest in the exhaust somewhere???
 
i agree a compression test is needed if you havent done that im thinking a stuck or badly burned intake valve would make this happen
 
Someone with very good knowledge of these tractors once told me the sticking valves are very uncommon when I first starting exploring my challenges with this tractor. Regarding critters.. I considered this as well... what are the procedures to check for nests etc...? The muffler was a little loose from manifold on this tractor for a while...I wonder if a dirt dauber built a nest?
 
Not real recently...last time I did I remember one reading to by higher than than others... test was done on 2/10/13 and tractor was doing the same thing then... results were:
1 - 90
2 - 90
3 - 90
4 - 105
 
Not sure how to answer it....it does not come and go...so it is consistent from that standpoint but the burbs are not every second as it runs...does this indicate ONE valve/cylinder has a problem?
 
To get that much pressure back through the intake there would need to be an intake valve open when a piston is coming up on compression. Your previous compression numbers don't indicate that but I would recommend doing another test.

Mark
 
is it popping out the intake and exhaust..drape a shop towel over end of tail pipe..if it sucks it in the pipe ..exhaust valve is leaking..if only popping out intake just intake valve is leaking..i would rev it to 6-700 rpm listen for any change in popping tempo..if comp. # are the same from a yr. ago it seems its a sticking valve..treating gas and oil might take care of it..if not you may have to remove side cover and treat the lifters
 
Give this a try. Take a quart of ATF and pour it into a gallon of gas and run it with that. If you already have a good bit of gas in it then use that and add as much ATF to it to bring it close to that mix and run it. If it has sticking valves or carbon that should clear up the problem
 
(quoted from post at 08:27:53 02/17/14) I sought help a few weeks ago regarding my sick sounding '49 8n. Yesterday the weather was nice enough to work outside and trouble shoot. I covered off on all the easy potentials...drain gas, checked plugs, checked plug wires, etc. I paused and just listened to the sickness and soon realized this tractor was "burping" air out of the air intake as well as muffler. Upon further investigation, I noted that the air breather tube (from carb to cleaner)seemed hotter than what a breather tube should be. I pulled a rookie mistake and took off oil bath cup and when she burped oil spit out from cleaner and caught on fire for a second when oil hot muffler!

What would cause exhaust (I assume) to be be forced back up through the breather tube. A few other points to maybe help a kind member diagnose..

1. No exhaust smoke comes through the air filter. When it burped with cup off oil did come out but no exhaust.
2. Not too long ago I reattched the muffler to the manifold...could I have created a blockage?
3.I checked the spark plug wires and as far as can tell they are all connected right?
4. Gas is good.
5. Oil batch cup was filthy...did not realize if could get this cruddy.
6. There was no change in how it ran with oil cup on or off (I did not think there would be) but I almost lit tractor on fire doing it!

Guys, I would appreciate any guidance. I am not a complete rookie...having restored another 8n from top to bottom, but this particular 8n has me totally confused....



Could you be running lean such as bad carb adjustment or a bad vacuum leak?
 
(quoted from post at 14:24:20 02/17/14) Old... thank you. Not sure what ATF is? Some gas treatment yes?

Automatic Transmission Fluid; does the same job as Marvel Mystery Oil (MMO) without the price.

It is a solvent and will keep everything clean and deposit free. Add about a cup to every 10 gal of gas. I add some everytime I fill up.
 
Guess you do not read many of my posts. ATF is something I have talked about for over a decade on here. Yep transmission fluid is ATF Dextron 3 is what I use
 
I did add a little Marvel when I refilled the gas tank (4 gallons only) with fresh fuel....

What is the accepted ratio of marvel or transmission fluid to gas for an 8N?
 
(quoted from post at 16:27:53 02/17/14)
3.I checked the spark plug wires and as far as can tell they are all connected right?
You don't sound sure about the plug wires, I would double check to make sure they are wired correctly.
 
You are very correct... my wires are crammed in the tube over the block... when originally wired it I numbered the boots that plug itno the dist (fron mount) and now the numbers are gone... how I "Know" the wiring is correct...longer ones on the bottom... Always a possibility of a boo-boo here. That tube does not allow me to do a visual from dist to plug.
 
Next time your in a store that has Marvel Mystery oil pick up a can of it and read what it is used for. Then use ATF in its place. ATF does the same thing as MMO but at half the cost
 
If you have a multimeter you can measure continuity from one
end of the plug wire to the other end to make sure it goes where
you think it goes.

If not, you can use a battery on one end and a light bulb on the
other end to make sure you've got the same wire on each end.
 
Yes, but does it smell as good!!! Haha! Thank you. I am restoring a Farmall Cub in my garage here in Houston. My sick 8N is up at my land an hour and a half from here...which makes trying all these very good tips tough...cause I have to wait to go up there on weekend. I want to bring the 8N home to give it the full once over... but last time I had my 16 foot trailer in Houston...someone stole it!
 
Ya I could not handle having to keep a tractor away from my place of living. As for a cub BTDT and did one for a friend a few years back.
As for the MMO and ATF ya the ATF does not smell as good but for half the cost I can sure as heck live with out the good smell. LOL
a145930.jpg
 
Went to a seminar on biodiesel several years ago. The conversation worked its way to putting tranny fluid in a Powerstroke. The instructor said when they pulled the head on that engine the combustion chamber looked like it had been power washed on all cylinders. Apparently they were testing the effects of different types of "fuels" for diesels. This tranny fluid was used, but filtered, from waste.
 
Yep ATF will clean up things and free up sticking parts real well guess that is why I keep saying to people they should use the stuff. Shoot I have an old pumper oil can I use that has ATF in it
 
(quoted from post at 08:53:11 02/18/14) Yep ATF will clean up things and free up sticking parts real well guess that is why I keep saying to people they should use the stuff. Shoot I have an old pumper oil can I use that has ATF in it

I love the stuff, and Old you turned me on to it. I haven't bought any PB Blaster in a year or so.

I buy cheap Type F ATF at Wally World and mix if about 60/40 with lacquer thinner. It is my go to penetrating fluid, valve unsticker, multi-use product.

Put it in a spray bottle, shake and go...
 
Ya funny how when I first joined Y-T and said things about ATF and had people tell me I was dump and stupid and it did not work but 10 plus years later well people have found out it does work well
 

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