mist coming out of flame arrestor?

tic

Petty Officer 2nd Class
Joined
Jun 27, 2007
Messages
140
Well, the cracked block/ JB Weld repair is holding great.... the new impeller is pumping water great... Two new things... Checked outdrive fluid level and it was off the dipstick!... Added 9 oz.. but no visible water in the remaining fluid.. Found fill screw loose!... Tightened the heck out of it and then put silicone over the screw just as added security... The boat sat for a week since last used and I saw a brown spot under the bullet and (hopefully) most of that 9oz. leaked out drop by drop over the last week and not the last time we had it out... Anyways it purred today and no abnormal noises or sounds... I think I got REAL lucky.. However, that being said, when I was watching the engine to see if my JBWElD repair was holding (wife driving boat, 3000 rpm, 3.0 liter OMC)I saw occassional "Misting" from the flame arrestor... It was a very humid morning with the temp and dewpoint being the same.. Hoping this was just water vapor?... put my hand around the arrestor and after it misted a few times I smelled and did NOT smell fuel... Engine oil is honey brown and so is outdrive fluid... thoughts?
 

Mischief Managed

Lieutenant Commander
Joined
Dec 6, 2005
Messages
1,928
Re: mist coming out of flame arrestor?

As air pressure drops, water comes out of suspension in the the air and becomes visible as water vapor. It's easy to see on the top of an airplane wing when the plane rotates to takeoff on a humid day. The air pressure around the engine's air inlet drops when the engine is running and can easily cause this.
 

milkyway

Chief Petty Officer
Joined
Jul 31, 2004
Messages
535
Re: mist coming out of flame arrestor?

Outdrive oil is honey brown? What's the color of a fresh oil?
 

tic

Petty Officer 2nd Class
Joined
Jun 27, 2007
Messages
140
Re: mist coming out of flame arrestor?

O.K... outdrive oil is different color than engine oil but it is NOT milky... I'd say it's translucent yellow?....... I was hoping it was water vapor coming from the flame arrestor and that the situation is normal.. My worry was that somehow water was entering the fuel system at the carb and vaporizing, coming out the arrestor as mist.
 

milkyway

Chief Petty Officer
Joined
Jul 31, 2004
Messages
535
Re: mist coming out of flame arrestor?

that mist can be most likely unburned fuel vapor that is being redirected to the carburetor, thru the flame arrestor.
 
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