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M carb/manifold frosting up


JaredT

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We use the M to go get firewood and when it is warm out she runs good, no issues, but when it's below 30 I keep getting this.

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It will start fine and run great until it freezes the carb and manifold. If we shut it off and wait 5 to 10 minutes she will thaw out and be fine. If it's below 15 or so, it will do it again, otherwise it usually only does it once.  The engine never moves off of the cold setting on the gauge in the winter, I probably should cover part of the radiator, but I don't see how that would affect the carb as I am assuming it is just the cold intake air freezing it up. I  have cleaned the breather and everything to do with that thinking it might be restricted, no luck.  We bought the tractor about 4 years ago and had this problem every winter. Can fire up any of the 3 C's and none of them will do it. Any suggestions?

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You are getting a perfect combination of humidity and temperature. It is a common occurrence especially under a light load that does not let the engine heat up and a M will run "cold" when just idling or light chore work. When the fuel is vaporized and mixes with air the heat comes out of the air and results in the frost you see. It is a normal thing to happen in these weather conditions, the 450 I had would do it. You will find on a dry day it won't do it or only briefly. Usually as you indicated shutting her off for a while should let it thaw out.

If the tractor is not warming up at all your thermostat may not be working or someone removed it.  On a cold day the gauge should at least get to the "L" or "D" of "cold". I used to cover the grill on my 450 with a piece of canvas, it seemed to help a bit. 

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My 400 does that sometimes but never noticed it causing any issues so I never worried about it. Pretty common on certain days tho. 

 

 

 

 

 

 

 

 

 

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1 hour ago, iowaboy1965 said:

My 400 does that sometimes but never noticed it causing any issues so I never worried about it. Pretty common on certain days tho. 

 

 

 

Yes my old M that I used for hauling winter manure used to get this but I cant say it ever affected how it ran.  A mechanic at the time said there was a shield you could get to protect the carb from the weather and keep the warmth around the manifold but I also had a winter cab on it which probably helped.

The idea about the engine running too cold is interesting but its my understanding that the manifold itself is supposed to conduct heat down to the intake and not so much from the engine block.

 

 

 

 

 

 

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In the summer, it comes up to temp and temp gauge operates fine. Without a thermostat it wouldn't necessarily get up to temp in the summer, would it? Mind you this tractor never gets worked hardly at all. Pulling a hay rake or a water wagon, nothing to make the engine work. 

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13 hours ago, JaredT said:

In the summer, it comes up to temp and temp gauge operates fine. Without a thermostat it wouldn't necessarily get up to temp in the summer, would it? Mind you this tractor never gets worked hardly at all. Pulling a hay rake or a water wagon, nothing to make the engine work. 

All the more reason for a thermostat.

An engine wants to be at operating temperature so it operates at the most efficiency.

Be careful when you install one if the old one was removed.

The one end of the thermostat must move freely in the cast iron.

As it opens, the brass of the thermostat moves inside the cast iron.

If it cannot move, it sticks shut or open and then overheats or stays to cold.

I needed to Dremel away a lot of corrosion before mine wound set in the casting and easily move up and down.

Mine runs most of the time at the intersection of the white and green on the gauge now.

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dont worry about that frost! that is perfectly normal situation . its called the venturie effect. as the air is passing through the venturi it has to speed up and cools off dropping temperature. every carburator does this. even when 80 degree's outside you can hold that area and it will be cold. you are not going to change it.

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Carb ice! in avation its called the silent killer! you need to warm up the air going in the carb. mikem has the right idea. also my grandfather install a engine bra over the engine to keep it warm and  it also kept blowing snow out of the engine.

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I guess I didn't realize that the engine would run up to temp in the summer without a thermostat, I figured it would it would run on the cold side of the gauge. I guess I just never thought it through. 

I wouldn't worry about the frost on the carb if it wasn't freezing the carb and stalling the tractor. I am thinking if the thermostat was in there and it got up to temp, it would probably warm the manifold up a bit more, keeping it from freezing by more heat transferring throughout the manifold?

I will be installing the thermostat in the spring when it warms up and see what we get next winter. I wouldn't mind doing what Mike pictured, but I want to keep it original, likely going to paint it in the future, but the it won't be going to the woods anymore. 

I really appreciate all of the input, I learned a few new things already. 

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1 hour ago, JaredT said:

I guess I didn't realize that the engine would run up to temp in the summer without a thermostat, I figured it would it would run on the cold side of the gauge. I guess I just never thought it through. 

I wouldn't worry about the frost on the carb if it wasn't freezing the carb and stalling the tractor. I am thinking if the thermostat was in there and it got up to temp, it would probably warm the manifold up a bit more, keeping it from freezing by more heat transferring throughout the manifold?

I will be installing the thermostat in the spring when it warms up and see what we get next winter. I wouldn't mind doing what Mike pictured, but I want to keep it original, likely going to paint it in the future, but the it won't be going to the woods anymore. 

I really appreciate all of the input, I learned a few new things already. 

every tractor does this. but yes a thermostate in winter would help. plus when you stat the tractor just let it run at an above idle  for  15-20 minutes before going to work wide open. it will help some.  that is why the older vehicles had that pipe going from the exhaust manifold to the air cleaner with a flap inside. it would draw warm air off the manifold. i run these tractors all the time with frost on the intake there and have not run into a problem from that.  the faster you run the engine the faster the air is being drawn into the intake ,... so use a higher gear and less rpm, GEAR UP THROTTLE DOWN . had a nieghbour here about 50 years ago, he would go in the house and get his boiling kettle off the wood stove and pour boiling water down the intake and over the carb then start the W6 tractor. 

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I usually start the tractor and let it run 10 to 15 minutes at around 1/3 throttle while we get hooked up and whatnot. By the time I drive 1 mile to the woods, she isn't running very good. I have tried idling down the road and WOT, doesn't seem to matter. I thought maybe humidity in the air would matter, but no difference there. 

I can make it work and will put a  thermostat in it, but it is super frustrating as I get minimal time to get wood and she keeps wanting to fight me. 

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We always covered the radiator so it would run warmer , put some (heat in your gas will help . My dad always put a piece of inner tube on the front side of the carb on his H so the wind from the fan wouldn’t blow on the carb , it did help . Soon as the block would get warn the frost would go away .

Danny

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Yes Matt , sorry Heet , I try to tell folks to run better gas with out ethanol in their old tractors but everyone does something different .

Danny 
 

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I don't use ethanol gas, especially in anything with a carburetor because it's so corrosive. Newer vehicles can tolerate it but nothing older. Lead replacement therapy is also a good thing but even some two cycle oil added to the gas works well. Don't have to get crazy unless you want to scare off mosquitoes.

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On 1/28/2023 at 2:54 PM, Dell said:

Carb ice! in avation its called the silent killer! you need to warm up the air going in the carb. mikem has the right idea. also my grandfather install a engine bra over the engine to keep it warm and  it also kept blowing snow out of the engine.

So you know about LL100 avgas?

Great stuff in lawn mowers and older tractors.

But it has to be expensive now?

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