LP, cold temps and Impco J Vaporizer

I would have to imagine someone here is familar with the Model J Impco vaporizer. What I am wondering is what would cause it to frost up, even in moderate and or warmer temperatures, right now being colder, its freezing up and shorting the carb from fuel or so it seems, look under there and its frosted up but good, so is the fitting on the carb inlet, this is a 172 Cu In. in a Ford 850.

Starts up and runs fine for a little while them sputters out, seems if I put a furniture blanket over it, the engine heat eventually makes it right, same thing has to be done even if I take it out from the heated garage.

In '04 I rebuilt it with a kit, replaced that safety shut, external cylindrical thing with a positive wire to it. Do these need periodic service, sludge up from LP, was no big deal, to rebuild, seems it was pretty decent in colder temps for awhile, but I think the past few seasons its done this, the model J on it does look old, the button on top is pitted from rust, is there a modern equivalent or are they available ? Also seems the tractor runs real cool, I replaced the thermostat a few years back, coolant level is up also, so I believe its circulating through the vaporizer. Had gone out with it last night to retrieve a deer that I got shortly before, annoying as heck, finally cleared out, but was just wondering what anyone with LP power/conversions thought, seems simple enough to correct, but was wondering what may be the actual trouble, LP must be staying as a liquid, and we know how that works in the cold LOL !!!

How is the coolant routed to the vapourizer and are the lines hot?

Y0u should start on vapor and turn to liquid after waem up!!!!

Make sure you have coolant flow to the regulator. the cooling passages can get clogged up and with no or low engine coolant supply to provide heat to the regulator it will freeze up. Yes coolant from a cold engine can still provide heat to the regulatorBecause the coolant is at ambient temperture and the expanded gas is much colder.

coolent level low - vaporizer freeze up

Do you even need to switch it to liquid for such a light load as pulling a deer ? I had a forklift and it ran fine on just vapor only.

Don't overlook the possiability of water in the fuel since you mentioned it does it at warmer tempatures also. Since it is a real pain to extract the water from the tank,I find it a good idea to temporaryly connect a known dry tank to test before draining the tank. To eliminate the water in the vaporizer pour a few drops of camp stove alcohol into the hose before connecting the dry tank. If it does turn out to be water,don't just dump in some alcohol without removing the water from tank. Best and most thorough method to remove water is pulling the tank into a deep vacume with a Hvac vacum pump.

It is probably best going to liquid after warm up because it doesn't take long in cold weather to drop pressure in tank running vapor. In Texas you can run vapor almost yearround due to mild tempatures.

I should check the line plumbed into it, the temp gauge since I hooked it up, clean radiator, even in hotter temps, does not seem to get over 170, when the radiator is covered it may get warmer, have one on the hook, to cut up before dark, will have to check that line.

I see the comments in response, but this has the same set up as a forklift, possibly I've missed something, but am aware that factory LP tractors had tanks to allow vapor only, I'm unsure if that can be done with a 30lb tank, same as a forklift, screw it on, turn the valve on and thats it. I does appear a tank without much fuel does not seem to do this, could be the liquid only and temps, also saw the response about water, thats another scenario, darned thing frosts in the summer heat too.

Never considered that, will keep that in mind, its just kind of annoying, I thought maybe something was wrong with the vaporizer.

Coolant not hot enough, not vaporizing or like you said a moisture problem, must be condensation over time in these tanks ?

Coolant was up, but it does seem to me the motor does not get very hot, even lately in the summer, thermostat not that old, stuck open maybe, will have to see about that, usually a motor will get to temp, and if you watch the gauge you can see it drop when it opens. Will have to look into that as well.

Are you saying the passages in the Vaporizer get clogged ? If that is a concern, I suppose a new one or rebuild kit is in order, last time I bought the kit, I went to a local forklift outfit, they raked me over the coals for $160.00 should have been a lot less or a new vaporizer, needed it, holiday weekend etc. I think I can find them on the web.

frosting over means lack of fuil,when dealing with lp/

Line ? There should be two lines of coolant, with flow.
Coolant temp should be 195F.

My forklift was missing some parts and the tank and holder so I just hooked it up to a barbque tank.

My experience is with forklifts. A fleet of 250! I feel the old J is the best most simple vaporizer. I find if its frosting its not getting coolant for one reason or another. I've seen a few conversions that because of space or whatever the plumbing is not optimum to prevent a little air bubble. I've seen a lot of LP forklifts start up when it zero outside.

My guess is that you're not getting any coolant through the vaporizer. I think that any coolant, regardless of temperature would supply ample heat to vaporize the fuel. I had a freeze on my 400 Case once. Everything appeared to be in order but I had a plugged coolant line to the vaporizor.

Just when you think youve heard it all,Let us know what you find out, Ive only used lp tractors for the past 50 yrs,electric shut off could restrict fuil flow.When you shut an lp john deere tractor off just go put your hand on the electric shut off and you will fill it get very cold due to no fuil???????????

(quoted from post at 16:20:52 11/30/12) frosting over means lack of fuil,when dealing with lp/

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That statement leaves me a little confused. When a convertor frosts up the LP will no longer all be vaporized and the result is that liquid fuel will exit the convertor flooding the engine.

One hose of the upper radiator hose, small diameter, and one from the left side of the block, I do suspect its running cool as well, now yesterday I fired it up, used the loader to hang and skin the deer, it sputtered out once, I had put the furniture blanket over it, to collect engine heat, did not re-occur. I will have to look into this further, once its back in the garage, which ought to be soon enough, coolant lines did not seem warm. Possible like mentioned above its clogged and maybe a stuck open thermostat, funny the one I took out a few years back appeared to be stuck closed.

I'll post a follow up, though annoying, still an interesting and entertaining problem to solve, my guess is the coolant line, as per above and what I see, will have to take that vaporizer off when in the garage, see whats what.

That is a fool of a spot to take coolant after the thermostat and return coolant to the block. How pray tell is warm coolant going to flow?
The hot line to the converter or to a cab heater . Is from as close to the underside of the thermostat as possible. Return line from the converter needs to connected to the water pump inlet.

Good point, could be a less than desirable plumbing job, when I get 'er in the garage I am going to take closer look at that routing, it did not make a lot of sense to me, based on the concern for flow, from the hot side, and being pumped just the same,I will have to post a photo of it when I follow up.