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somebody 
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Joined: 03 Jun 2010
Location: western NC
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 Topic: moisture around Carb.
Posted: 03 Jun 2011 at 1:36pm |
I have a D17 226 gas engine, There is moisture builds up around where the carb bolts to manifold, I noticed last winter there was frost forming there but didn't think much about it. I ran it about 2 hrs. and the moisture was still there.
Anybody got any ideas?
Thanks and wish everyone a great weekend.
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Stan R
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Joined: 03 Dec 2009
Location: MA
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Posted: 03 Jun 2011 at 2:18pm |
My guess is that it is standard heat of evaporation. i.e. when a liquid goes to vapor, it absorbs heat, hence cooling the metal. Not to worry.
http://en.wikipedia.org/wiki/Enthalpy_of_vaporization
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Dick L
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Location: Edon Ohio
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Posted: 03 Jun 2011 at 2:24pm |
condensation caused from temperature difference between the inside of the throat and the outside. Moisture in the air collects in that area. If you wear glasses and have the air conditioner turned real cold in your car then get out of your car into hot humid air you get them fogged up. That is the same thing.
I used three tractors yesterday and had the same thing on all three. Actually I used four but the one was diesel and I didn't look at it. I lift the sides on the Oliver 77 to turn the gas of as soon as I shut it off and it has more moisture that the Allis B or the Farmall C that I used.
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Brian Jasper co. Ia
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Posted: 03 Jun 2011 at 2:34pm |
Yep, it's humid out there. My CA and Oliver 60 do it too.
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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford
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somebody
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Location: western NC
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Posted: 03 Jun 2011 at 2:53pm |
Mystery solved, Thanks guys, The main reason I was asking is ever now and then the engine would shut off but would crank right back up or if it started to die and I caught it in time to quickly pull choke and right back off it would keep running so I was wondering if I had water or carb. trouble.
I really appreciate you guys you help a lot of people.
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R.W
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Posted: 03 Jun 2011 at 5:08pm |
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My Farmall smta dose it all the time nothing to worry about.
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In Search Of: 1958 Allis Chalmers D17 Diesel serial #9643D
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DrAllis
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Posted: 03 Jun 2011 at 5:11pm |
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All the ones that run really good do that.
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j.w.freck
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Posted: 04 Jun 2011 at 10:46pm |
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in aviation this is known as carb.icing or induction icing.this really gets the pucker factor meter pegged out when you are on final approach to the runway and need some more power to get to the runway,you apply power and nothing happens.all you can hope for is a real good backfire to clear the ice...thats what they make checklists for...
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Coke-in-MN
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Posted: 04 Jun 2011 at 11:05pm |
Venturie principal , air rushing into engine theough a small opening, then expanding creates a cooling effect, moisture in the air condenses out on a cooler surface.
If you have ever drained a tire of air by taking the valve core out of a fully inflated tire you will see and feel the same effect at the valve stem as air rushes out it will form ice on valve stem.
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Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something.
"Challenges are what make life interesting; overcoming them is what makes life meaningful."
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CTuckerNWIL
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Posted: 04 Jun 2011 at 11:58pm |
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My 45 does it. If it gets real frosty in the winter, sometimes it will cause the engine to not run just right. I put a heat reflector tin shield on it when I need to plow snow. If it warms up at a lower rpm for a bit it doesn't bother much.
I had a 250 inline 6 in a 66 Chevy tuck once that wouldn't pull itself down the road after a cold start and a 3mile drive. I asked anybody I could think of what to do about it other than warming it up at an idle for several minutes. I finally found a guy with an answer by accident. He told me to go to the Chevy dealer and ask for an insulator block for it. It cured the cold start frosting carb. It was just a carb to manifold gasket that was about 3/8 of an inch thick.
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Dave H
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Posted: 05 Jun 2011 at 8:03am |
 j.w.freck wrote:
in aviation this is known as carb.icing or induction icing.this really gets the pucker factor meter pegged out when you are on final approach to the runway and need some more power to get to the runway,you apply power and nothing happens.all you can hope for is a real good backfire to clear the ice...thats what they make checklists for... |
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JW, I think they are tlking about moisture on the outside not on the inside of the venturi?
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CTuckerNWIL
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Posted: 05 Jun 2011 at 11:48am |
Dave H wrote:
j.w.freck wrote:
in aviation this is known as carb.icing or induction icing.this really gets the pucker factor meter pegged out when you are on final approach to the runway and need some more power to get to the runway,you apply power and nothing happens.all you can hope for is a real good backfire to clear the ice...thats what they make checklists for... |
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JW, I think they are tlking about moisture on the outside not on the inside of the venturi? |
Yep, moisture on the inside could be a real bummer, specially in a plane.
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wkpoor
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Posted: 05 Jun 2011 at 2:18pm |
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The technical term is Bernoulli's Principle. A increase in velocity of a gas will cause a corresponding reduction in pressure and thus a reduction in temperature to. Typical carb venturi will drop temp 30 degree so 60 degree air can be the worst to from ice because warmer air holds more moisture referred to as RH. Aircraft have a feature called carb heat to help eliminate ice in the venturi at low altitudes with throttle at idle. Old cars like my 69 Impala had carb heat too. For the most part is should go away at higher throttle settings and with warm engine. The closer to closed the throttle plate is the worse the condition will be.
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