1968 4020 Propane will not start in cold weather

Rapidrob

Member
I tried to start the tractor yesterday in 20 degree weather to plow the snow.
The tractors hydraulics were turned off at the pump and the engine spins freely and fast. I could smell propane and see light distortion as propane escaped from the air intake after 30 seconds of cranking the engine over.
The throttle was at 1/2 way.
The engine has always started up instantly in warm weather.
The ignition parts are new.
Tank was at 60% full.
Valves work ( liquid/vapor)
I tried three diff batteries,all new and full charged.
Unit is 12 volt ( converted )
The engine does not have a block heater.
The propane converter ices up after a few minutes of cranking.
If I shut the propane off and crank the engine for a few minutes the engine will catch and run for two seconds then die.
Please advise.
 
I'd suspect regulator trouble, it shouldn't ice up like that. You are starting on vapor, right? Water needs to be moving right away through the regulator when using liquid valve, or it will freeze. Vapor prevents that during start and warm up, then the liquid valve can be turned on and vapor off.
 
Are you trying to start on vapor or liquid? Should start on vapor in cold weather as there is not enough heat in the cold engine to keep the converter from freezing up. Switch to liquid after the coolant warms up some.
 
Thank you,I'll try again today on vapor only. It's -1 outside right now and may get into the 20's later on.
This is the first time it has not started in cold weather.
If it does not start up, should I try to heat the converter with a hair dryer or the like ( keeping it cool enough not to hurt the diaphragm inside ) or starting fluid?
 

Check coolant level.

Does your tractor have a choke??? My MIL's propane 4010 wouldn't start the other day when it was
cold....started good all summer. I noticed that it did have a choke and tried it and it started right up.

HTHs
 
put your fuil lever all the way to ideal possision than move it up about 1/2 inch. To start lp it.s just the opposite as gas tractors. will not start as good with any throttle more than 1/2 to 1 inch. And start on vapor after warms up switch to liquid. I would not start any of my tractors at 20 degrees. If you hear fuill coming threw radiator you need to have vaporizer repaired.
 

I don't know about the 4020......4010 carbs have a choke lever on the back side of the carburetor. Father
in law had run a piece of baling wire back to the platform and run it through a hole on the opposite side of
where the "diesel stop" knob. Book shows that on LP tractors, a cable runs from the carb to the choke knob
(located in the "diesel stop" knobs place).

I used to run a AC cotton stripper that had a 250 chevy engine on LP (it had been converted from
gasoline). It always started in the cold without any choke.....that's why it surprised me that the 4010
needed to be choked.

HTHs
 
it finely got warm enough to play with the tractor. Won't start. I really smell propane. After a hard look there is a choke on the "carburetor". It has been wired open for decades. There is a knock out on the dash that has never been punched out for the choke cable.
I removed the carburetor to see if it was clogged. What I found was not expected. The was a layer of propane "stink additive" almost 1/2" thick! I took the carb apart. What a smelly mess. Two cans of carb cleaner to get that jelled crap out of everything.
I did notice that there is the largest "needle valve" in the bottom of the carb I've ever seen. At least as big as you little finger.
I put everything back together again and opened up the Vapor valve and using a remote starter switch, turned the engine over. That 6-banger jumped into life instantly without a misfire. ( choke still wired open)
I have no idea how to adjust the needle vale at the bottom of the carb.It does not bottom out like a gas carb jet so I just left it where I found it. It's about 1 1/2 turns out and does not stall out when goosed. No smoke.

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thanks for all your help.
 

I live at 7,000 feet ASL. Anyone have any ideas what a good setting for the "load valve" should be set to in the number of turns out? I found a portion of an old JD manual that suggest 5 turns out for a ASL of 1,000 feet.
Thanks for your help.
 

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