1946 John Deere B Backfire

Rideawaysenior · May 3, 2009

A little help needed here. This is my first Deere, and I love it. I found this machine sitting in a field. It had been there for 8 years had a rusted out rear rim and all tires were shot. Last year, I got her running with little effort. This year after mounting new rubber all around, I went to fire her up. Ran a bit slow at first and then gradually picked up. Now she"s backfiring through the carb. I"ve also noticed the following. After it runs for a while, it takes some cranking to get her started again. When cranking, I notice a little smoke blowing out the exhaust. Just before it pops, the smoke gets a bit heavier. This may have no corelation but these vertical two cylinder low RPM engines are a new animal to me.

A little more info, when it runs, no smoke or funny noises, and no leaks anywhere. I did drive it and it seems to have plenty of power to move along. Also, when I adjust the choke and restrict the air just the slightest bit, the backfire stops and it runs smooth. The tractor also surges on idle.

Jack

garytomaszewski · May 3, 2009

Sounds like a little carb tuning is in order; lean so the choke richens it enough to smooth out & surging at idle all point to carb adjustment.

Lanse · May 3, 2009

that sounds about like what my allis C was doing when it had a stuck valve and knocked the rocker off the pushrod. Mabey one of your valves is just sticking a little???

garytomaszewski · May 3, 2009

Hey Lance, perhaps you should listen and learn from the advice given to you before you start sharing "your knowledge".

davediehl@hotmail.com · May 3, 2009

I would start in the carb. A lean condition will pop and backfire through the carb. Your comment about the choke is a tell tale sign that its fuel or the lack of. You might see some grey or light smoke running lean, but it will be black when its too rich. Run the fuel out of the carb and allow the unit to cool. Then you can try a can of gumout carb cleaner, take off the pipe plug on the side of the bowl housing and spray in the carb cleaner until the bowl is full. Replace the plug and turn on the fuel. This will run some of the cleaner into the passages and may clear out whats in there. You may still need to tear it down, but its a start on diagnostics.

Andy Motteberg · May 3, 2009

Sounds to me like a carburetor problem. Make sure there is good fuel flow to the carb. Make sure the adjustments and float level are correct. If this won't fix it, try rebuilding the carburetor. Good luck.

old art · May 3, 2009

lance said what his problem was. to help look for what might be the man's problem also.
old art

Gary from Muleshoe · May 4, 2009

Why is there always some jerk like you on here putting Lanse down. He is a young man trying to learn about tractors. People like you are why our young people have no interest in things like this. Instead they are out "Doing there own thing", like drugs and alcohol. Lanse has just as much right posting his ideas and comment on here as you do, so back off.

garytomaszewski · May 4, 2009

Art, you might want to search and read some of lances questions and the answers he was given by some of us who worked on these tractors when they were new, and then read what lance did to firetruck up the job by using his "experience" instead of taking the advice .

Rick in Michigan · May 4, 2009

Sounds to me like it's sucking in air somewhere in the fuel circuit. Don't overlook the gasket in the glass bowl, and the seal in the fuel valve (if so equipped).

Rideawaysenior · May 4, 2009

Rick,

Thanks for the tips, I just replaced the bowl gasket so hopefully it's not that. I rebuilt the carb last year and ran it off the starter fuel tank and she ran ok. I'm wondering if maybe that sitting over the past year as after I got it running I just left it be as I didn't have the spare capital to invest in the tires it needed. I'm going to take the carb off again and give it another cleaning and see what happens. I toyed with the carb settings a little more today and it seems to have smoothed out some. I did pour some seafoam additive into the gas and crank case per the manufacturer recommendations just in cast it was a stuck valve. The can of Seafoam also says that it's a good fuel system cleaner and conditioner. Being that this engine is the age it is, I figured it wouldn't hurt.

Another thought here, could the fuel cause the backfire? I'm using 87 octane without any lead substitute. I have a 46 Farmall H, and I usually run lead substitute when I have it and it seems to make that tractor run much better.

Jack

garytomaszewski · May 4, 2009

Jack,
Your fuel questions always start a great debate. That B was a low compression all fuel tractor so 87 octane is way more than it ever required, most regular fuel of the time was 65-70 octane And lead substitute is only good for the pockets of the company that sells it. Lead was first used as an octane booster, with the added "benefit ??" of cushioning the exhaust valve seat. Lead substitutes do neither of these. In 60 plus years I'm kind of sure that the valves have been retouched and if in the last 20 or so has had hard seats installed.

Anonymous-0 · May 6, 2009

Surging at idle says the idle passages have some crud in them,Backfiring happens on lean mixtures and bad condensers.

1946 John Deere B Backfire

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