Logo
FULL SITE MENU

Sweaty carb

S

Sam110

Regular Contributor
I just ran my newly rebuilt 18 hp (18304A) and observed a condition I have not noticed before which may or may not be normal.

While this motor is not running as I had hoped it would at this point I'm rather sure the carburetor is the issue. I could not get the high speed orifice plug out for inspection / cleaning nor the plastic "bearing" sleeve from the back of the low speed needle orifice .. hoping they would not be an issue.

The condition I'm referring too is a "sweating" around the back of the carb and the intake manifold as the motor ran. So much so that when the motor was shut down a milky mixture of water/fuel dripped out of the throat of the carb. ?? No doubt this water mixture is being drawn in as fuel and is effecting how it is running. What would be the likely cause of this?
 
No not at all !!-----When a liquid evaporates it needs heat.----Basic principal of a refridgerator.-------So when fuel goes through the carburetor it gets the heat from the aluminum casting.-----The casting is now cool and moisture from the air condenses on the outside of the carburetor body.-----All normal and simple .-----That is why some older cars and also small airplanes have " carburetor heating " systems.
 
Same reason a glass of ice tea sweats. It's called condensation (of the moisture in the air). The parts are cold because of evaporation and expansion---as racerone said. In the early days of airplanes, moisture collecting on the carburetor could freeze and cause the plane to crash.
 
Ok, yes makes sense it's certainly humid in my area. I really haven't noticed this condition on any of my other engines before and though this moisture being drawn in with the fuel could be contributing to the bad performance. I'll turn my attention back to that carb and hope I can get this problem smoothed out. Thanks for the input.
 
racerone said:
No not at all !!-----When a liquid evaporates it needs heat.----Basic principal of a refridgerator.-------So when fuel goes through the carburetor it gets the heat from the aluminum casting.-----The casting is now cool and moisture from the air condenses on the outside of the carburetor body.-----All normal and simple .-----That is why some older cars and also small airplanes have " carburetor heating " systems.
Click to expand...

Agreed.

Bill
 
It is a direct result of expansion as the fuel turns from a liqud to a vapor the temperature drops and the vapor pulls the heat out of the carb body causing evaporation (moisture) to form on the carb. Heat allways transfers from hot to cold simple physics. Put a cold beer in the hot sun it sweats until until it absorbs the heat. Put a hot beer in the fridge you not adding cold it is pulling the heat out through the refrigant.
 
Back
Top