Propane Engines in Cold Weather

My little NAMCO forklift is powered by a two cylinder Kohler engine. If I leave it outside in 40F weather or colder, it doesn't want to start. Liquid propane from the tank is converted to gas in a unit heated by exhaust and goes to a propane carburetor. Choking doesn't help. I finally concluded that the carburetor was getting liquid, making it too rich, the opposite of what I would expect with a gasoline engine. I shut the propane off and cranked until it started, then turned it back on. This is the only propane powered engine I have experience with. Am I correct or am I missing something?

Bill

Your diagnosis is correct.

If your usage is light, you could try a LPG tank plumbed for vapor withdrawal.
The tank will get cold and lose pressure if too much fuel is being used.

Am I correct in assuming that is an air cooled engine?

Normally the converter is plumbed to the radiator so that the coolant (even when cold) adds heat to vaporize the propane.

For such a small unit I agree with those who suggest a vapor tank such as a 20 lb. barbecue tank. Pretty easy to convert using a POL soft nose to NPT fitting coupled to a REGO fitting. You'll want to use a sealant that keeps the adapter from turning (making the setup more or less permanent) but anyone who fills fork lift tanks can easily fill a 20 lb. with the same fill hose.

When I was younger I once worked for an outfit that rented equipment and we used small vapor tanks for returned unit checkout so the next customer got a full 33 lb. tank. It was also much easier hefting the smaller lighter tanks for a quick check in the yard. We had a couple of 20# tanks and at least one 10# fitted up that way.

IIRC the Namco propane bottle is very small (smaller than a 20lb bar-b-que
bottle) to begin with.

I would try adding a 1lb bottle with the valve (remove the torch part) and plumb
that to the demand regulator for "cold weather starting".

Turn your tank 180 degrees so your siphon tube is now at the top. Only gas will go through the vaporizor now, but it will still act as a pressure reducer.

Can you keep it running with a few spritz of ether, until the engine warms up enough ?

gbent said:

Turn your tank 180 degrees so your siphon tube is now at the top. Only gas will go through the vaporizor now, but it will still act as a pressure reducer.

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Try the above. I’ve done that before when it’s cold out. Once the engine warms up, you can turn the tank back over and use it on the liquid.

Years ago we had a old propane tractor. It actually had two valves on it, one for vapor and the other for liquid. You opened the vapor valve to start it cold, once the engine warmed up, you closed the vapor valve and opened the liquid valve.

I have also used a heat gun to thaw a vaporizer before, I wouldn’t use anything with a open flame though. It also helps to run at low RPM with no load until the engine warms up, that way it isn’t drawing as much fuel and is less apt to freeze.

Can I ask why you leave the little guy outside in the cold to start with?
A red-headed stepchild?
Yes, they don't like this and the oil side that does the work won't either.
Hope you like rebuilding cylinders and replacing seals as you are asking for maintenance problems.
There are ways around the start problem but it is talking to you.
Bob

CarbideBob said:

Can I ask why you leave the little guy outside in the cold to start with?
A red-headed stepchild?
Yes, they don't like this and the oil side that does the work won't either.
Hope you like rebuilding cylinders and replacing seals as you are asking for maintenance problems.
There are ways around the start problem but it is talking to you.
Bob

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Are Namco forklifts really such delicate flowers? Up until last year I never had a forklift, or any other hydraulic equipment, sleep where it is warm. Some of the equipment had a lot of hours of operation in temperatures below zero. I have never had a hydraulic problem related to cold temperature operation.

gbent said:

Are Namco forklifts really such delicate flowers? Up until last year I never had a forklift, or any other hydraulic equipment, sleep where it is warm. Some of the equipment had a lot of hours of operation in temperatures below zero. I have never had a hydraulic problem related to cold temperature operation.

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Same with me. For the last 4 winters, my 60’s Clark starts right up (on choke) & runs with no issues down to the single digits. Below 40*, I let trans warm up at idle for 5-10min. before use but that’s it.

CarbideBob said:

Can I ask why you leave the little guy outside in the cold to start with?
A red-headed stepchild?
Yes, they don't like this and the oil side that does the work won't either.
Hope you like rebuilding cylinders and replacing seals as you are asking for maintenance problems.
There are ways around the start problem but it is talking to you.
Bob

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The forklift is a NAMCO 2015, 2000 pounds, 15 inches from the mast. Ray Behner has an identical one and likes it as much as I like mine. I have owned it since the early 1980s and had excellent service. It is normally parked inside a shop that is always at least minimally heated, but recently I have suffered from junk overload since I sold my airplane hangar and moved a lot of the junk I had stored in it to the shop. Until I dispose of most of it, I have to move the forklift outside to get workroom. Cold starts have only been a problem this winter because I never left it outside before. The exhaust pipe heated vaporizer seems to get working within seconds after the engine fires.

The propane cylinder is so tightly fitted in the engine compartment that I cannot use a different one or turn it over. Once I figured out the procedure, it hasn't been a problem. I was just curious about other's experiences.

Bill

On some older propane tanks, they do have vapor and liquid ports. You could set up a dual line, like I mentioned above about the tractor. Most newer propane tanks only have one liquid outlet though.

We’ve got all our forklifts under roof, but most are unheated. When it gets really cold, all propane forklifts are prone to freeze up, some worse than others.

The key to managing cold starts on propane engines, is to realize that liquid propane's vapor pressure drops substantially in extreme cold, and it will NOT evaporate rapidly without sufficient input heat.

Flipping the tank to get it to start on vapor is not a viable solution on a small liquid withdrawl tank- there simply isn't much evaporation surface to be had- that's why liquid withdrawl into a converter/evaporator is done in the first place.

The mistake most people make, is they fire up the propane engine, then try to run it hard to force it to warm up, which uses vapor FASTER than the evaporator can convert it from liquid to vapor.

Liquid cooled engines circulate engine coolant through the converter/evaporator. Air cooled engines frequently have the converter/evaporator mounted on or near exhaust or cooling shroud, in the flow of engine heat. Until there's sufficient heat there to accellerate evaporation, the evaporator will NOT do it's job, hence, liquid will flow through the demand regulator, mixer and manifold, and effectively 'flood' the engine by displacing all oxygen. hard on the demand reg and mixer.

Proper method- Open the fuel valve, start the engine, and let it idle. If it seems 'floody', then open the fuel valve, then close it, then start the engine, and once running, 'nurse' it by opening the valve every so often... it will eventually develop enough heat to the evap, to work fine on it's own.

Best way, if the temperature is really, really low- disconnect the bottle, and bring it inside, let it warm up. You could also... if it's a steel tank... slap an 'engine heater' magnet to the side of the tank and run it for a few minutes.

At -40F, propane only yields about 1psi... warm it to -25f, you'll get 8psi. For the demand regulator to meter properly, you need 11" water column, which a cold tank can DEVELOP, but until you have evaporator HEAT, it won't be able to MAINTAIN that pressure. Add heat!

This thread reminds me why I have an ex-US Army STILL forklift with a 3 cylinder air cooled Deutz diesel engine. It starts all the time every time and is never parked inside.

steve-l said:

This thread reminds me why I have an ex-US Army STILL forklift with a 3 cylinder air cooled Deutz diesel engine. It starts all the time every time and is never parked inside.

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To be fair any forklift in decent condition with a coolant warmed vaporizer will start up immediately too, and with less exhaust fumes to deal with.