Propane tractor question

Brad Dixon · Jun 20, 2014

Hey fellas. I have a Case 940 (Wheatland version of 930 I believe) and it is a propane tractor. Was running good but started having problems re getting fuel. When I opened the propane valves prior to starting the tractor, the oil bath breather started gurgling like propane was being pushed through the carb and back up the breather. I figured it had something to do with the regulator and I had that completely re-built. I put it back on and it is doing the same thing. Man who re-did the regulator said that problems with fuel system on these tractors is usually the regulator, not the carb. I don"t know whether I need to repair the carb or whether regulator wasn"t properly repaired or maybe it is something else. What would cause it to push fuel back up the breather? Tractor has been gathering dust because of this for quite a while and I really need to get her fixed. I would appreciate any advice I can get and thank you in advance for any response.

da.bees · Jun 20, 2014

I havn't had experience with the tractor you have but of all the others I've seen the systems work similar. Propane leaves tank as liquid at about 130psig on an 80f day. When liquid reaches vaporizor,the liquid is converted to vapor and sent to regulator at about 10psig. Some systems have the regulator between vaporizer and carb,others incorprate regulator into carb. Vapor is not under pressure as it leaves regulator. The vacum in carburator pulls and meters vapor acording to need of engine. So as you see no vapor should flow unless engine is running and is never at enough pressure(actualy none)to bubble liquid. I would say the regulator is malfunctioning in this case.

Bret4207 · Jun 20, 2014

I have a Cockshutt 30 with an aftermarket propane conversion kit by Brunner on it. If I press the "primer" button on the regulator, (I don't know if that what it actually does or what that button is called), I will often get the same type of gurgling sound. I always thought that since the engine wasn't running and the butterfly was closed going into the intake, the propane had to have some place to go and might be going through the air cleaner. It's worked like that for 20 years with no problem. I often have to press the button after running out of fuel to get it started. So I don;t know if the regulator on yours is a problem at all.

That's all I gots.

Mike M · Jun 20, 2014

You say you opened "valves" ? Not familiar with Case but on other brands you only open one valve for starting the vapor valve. You only open up the liquid valve once it is warmed up. Then I think you close the vapor valve.

Arnold Layne · Jun 20, 2014

Yeah, it's a problem in the regulator. My 560 Farmall will do that once in a while, when it does I shut the fuel off, start the engine and then turn the fuel back on. If it is just your high pressure valve sticking this may or may not allow you to get running. When the system is working right and it isn't wicked cold out you can open the valves in any order you like, and I usually leave them both "on".

Owen Aaland · Jun 20, 2014

It should take either 1/2" or 1 1/2" water column vacuum to open the regulator, depending on the model. There should be no fuel leaking through the regulator until this vacuum is applied. The problem you have is bin the regulator. They can be tested out of system by applying shop air to the LP inlet side and checking for leaks.

The amount of vacuum needed is very small. 1 1/2" of Water Column is the amount of vacuum it takes to raise water 1 1/2" as you s.u.c.k on a soda straw.

The primer button on a regulator works by depressing the diaphragm the same as applying vacuum would do.

big jt · Jun 20, 2014

Sounds like you have a system that is very
similiar to the OEM Cockshutt LP setup.

Cockshutt was one of the very few companies that
used the primer setup. I have a 40 that came off
the line factory. What is happening when you push
the primer button is the low side regulator is
being opened. Thusly letting low pressure gas
into the intake stream.

Pretty much everybody else felt the need to have a
choke and if the OP's Case is factory it has a
ensign system with a choke or starting circuit.

jt

big jt · Jun 20, 2014

Likely the high side regulator in your converter is bad.

jt

Hayrack · Jun 20, 2014

You either have a leaky diaphragm or your high pressure valve isn't closing. either way, both of them are in the regulator that you just had fixed. I would take it back and tell the guy it is still leaking. Incidentally, my manual for my 830 Case LP says to open the liquid valve for starting... It will start with either valve open but it starts easier with the liquid one open... I also have a primer button on my 830..

Brad Dixon · Jun 21, 2014

I want to thank all you guys for your comments. I'm going to take the regulator back to the man who repaired it since the general consensus indicates that is my problem. Thanks again.

Propane tractor question

Brad Dixon

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da.bees

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Bret4207

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Mike M

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Arnold Layne

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Owen Aaland

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big jt

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big jt

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Hayrack

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Brad Dixon

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