Updraft carburetor question.....?

Here is the background: I have a 1968 case tractor, with a gas engine that has four cylinders and an updraft carburetor.

When it gets cold outside, and the tractor is stored outside, I can't get it to start unless I put a tarp over the tractor and put a propane heater under it for a while.

I was thinking that it was so cold, under 30° F that the gas is not vaporizing correctly and causing the engine to flood. (I don't know for sure if this is the case or not.)

But anyhow, after a while under the tarp, with the heater running and the battery charger hooked up the engine will fire and run great, usually all day long. Starting and stopping regularly, ok.

This does tend to get old very fast, putting the tarp over and heating it up every day to get it to start.

Today, I was thinking that it was because of the cold air rushing into the carburetor that it wouldn't start. So instead of putting the heater under the machine, I put it on the hood next to the intake of the air cleaner, thinking that it will suck in warm air, mix with the gas correctly and start right up. Well it didn't.

So it's back to the tarp again, and it started right up after about 15 minutes of warming it up from underneath.

One of my mechanics that I talk to regularly says it's my heating the oil pan to make the engine turn over faster that is making it start, and that it has nothing to do with the carburetor.

I don't know if I have a question here or not.

But I was wondering if anyone had an opinion on what might be happening?

Is it cold gas in the carburetor bowl, that's being warmed up and then mixing with the warm air under the tarp that is making it start?

Is it the oil pan being warmed up to make it turn over faster to start?

It only happens when it is cold out.

Thanks for any and all advice you would care to share.....

Jim

 

Welcome to the forums Jim!

My tractor is a 1953 NAA [ford] but it has the same type of carb. Extreme cold has made my turn over slower but hasn't prevented it from starting. I do have to use more choke to keep it running when it's real cold. What weight oil are you using? is your choke operational? Is it possible you have moisture forming in the tank and that is freezing in the gas line?

 

Well, my diesel mechanic said I should change the oil and probably use a lighter weight for the winter, maybe I'll do that and see. I think it has regular 10/40 in it. Maybe I should try 5/30?

My coke does work, but when it's cold and I try and start it without the heater, the carburetor starts dripping right away, which made me think I was flooding it with too much gas. And I'd have to let it sit for a while before trying again.

It has a sediment glass bowl and I can't tell if it's clear with gas or has water in it all the way to the top

I did put a bottle of dry gas in it last week, but this is a recurring problem every winter.

I think this summer I'll build a one car garage for this machine and put it in next winter. But if it's cold out it will still be cold in that garage as it will be unheated.

Many years ago, I tried one of those dip stick heater units but that did nothing other than show burn oil on the heater dip stick.
I thought that was a complete waste of my time and money.

Jim

 

I would think 10w40 would be thin enough, I'm not sure 5w30 would give enough protection for an older motor. I run 20w50 in mine year round and don't have any issues although it does turn over slower when it gets down to freezing - but we don't [usually] get the cold you see further north. My tractor is stored in a 3 sided 'shed' on the side of my barn. IMO the biggest advantage to storing it under roof is keeping everything dry.

Have you taken your carb off and inspected it? Assuming it's like mine, they're pretty simple. Do you have a repair manual for your tractor? it should help you with rebuilding the carb if needed [plus it's handy for anything else that goes wrong] You can take the sediment bowl off and pour it out to see if there is water [or anything else] mixed with the gas.

 

I think I had this carburetor rebuilt a few years ago, I say that, and it's probably more than a few, don't know for sure. I wouldn't try it myself, not enough experience and or confidence to do it. I hate getting my hands oily or greasy. I could take the bowl off and check it but it isn't the easiest thing to re-seal. Everyone says to do away with the bowl and just put in an in-line filter. I really don't want to do that, but I may if I have to...

 

With full choke that setup will drip a little. I grew up with H and M and 300/400/450 Farmalls. Even the larger gas tractors have the updraft carbs. They will start and run fine in the winter. All of those tractors have the point condenser and battery fed coil, so when the drain on the battery is heavy the feed to the coil suffers.

The best way around all of it when you have decent plugs/wires/battery is a tank heater. Spend about $50.00 for a 1500 watt, plug it in about two hours before you want it to start and you're ready for business, no matter how cold it is. We used that setup when it was 20 below in Iowa - no problem.

 

Where to I place the tank heater?

Can you tell me a brand name to get? or a website where they are sold?

 

What state are you in, Jim? I'll dig something up for you.

Something like this:

engine tank heater items - Get great deals on eBay Motors, Business Industrial items on eBay.com!
You can them from just about any auto parts store, too.

Just run two lines from the heater to the block to circulate the water through the block. I have one on my tractor that's over twenty years old and still works great.

 

I'm in MA.
I've looked at the ones on ebay, just now, and they mostly say will connect to 3/4" hose lines.
My case tractor doesn't have any 3/4" hoses. Just two hoses from the engine to the radiator that I know of.

 

They will usually have block plugs and/or plugs in the water pump that can be removed. Another place you can get a connection is the water temp cable connection. You can put in a T and branch off that one. Often you can adapt a 3/4 to a 1/2 inch connection as needed.

 

Ok thanks for all your advice and help.

 

How about an electric block heater. The one that I have has a magnetic base that you place on the oil pan.

 

I found one of those magnetic ones on ebay and may get that, if I can't find one locally to save shipping.....

Thanks for that advice.

 

The type that heats the oil in the pan isn't a block heater. You need one that heats the water in the block then you'll be done with starting problems in cold weather. That is a tank type heater that circulates warm water through the block.

Another type that works nearly as well is the type diesel engines have built into them. Its a block heater that mounting into a soft plug hole. That's more difficult to install.

 

Jim,
I think the mechanic you talked to may be on to something. The problem may not be in your carburetor. Have you noticed an increase in the starting RPM's when you put it under the tarp and heat it up? When oil gets cold it gets thicker. By warming the oil it allows the engine to turn over faster. The reason I ask about the increase in starting RPM's is that some engines equipped with a magneto must turn over about 300 RPM's to produce spark. If you could identify the model and type engine you have it would be helpful.
A way to test this is to put a spark tester on one of your cylinders when you try to start it before heating it. If you don't have a spark tester remove one of the sparkplugs, reattach the plug wire and make sure the sparkplug is touching the head or some other ground. Then turn the engine over and watch the electrode on the sparkplug for spark. As mentioned above try this when the engine and oil are cold. Let me know if this helps. If it doesn't send me your model number and brand of engine.
jwatts