Gas leak on cold start in C182

[Stan Mlynarczyk]

Greetings,
I've read through some of the threads on cold start but have a few questions. I recently acquired a C182/P. It spent its life in the southwest so not a lot of cold weather starts in its history. In starting it yesterday (it was 12 degrees), I did the cold start procedure in the POH. Engine sputters/dies. I retry a couple of times but no joy. I am aware that I need to replace the O rings on the primer as it takes a good amount of force to pull/push in/out (the pulls were slow and I was getting gas into the primer). There is no gas leaking from the primer knob inside the plane. I have also read in other postings that the primer nozzles are likely clogged and the gas is not being atomized when it hits the intake. My one observation after I got out of the plane is that there was gas leaking from the cowl. I've read in one post where someone warned that if you do more than 3 strokes of the primer that you might see gas leaking from beneath the cowl. My question is whether the gas leak is considered normal and why?

 

[drummer4468]

Common but not "normal." Overpriming without the engine firing over, especially in the cold when gasoline doesnt evaporate/atomize as well, will allow the fuel to pool up in the intake manifold. Depending on where the primer nozzle(s) are, eventually gravity will take the liquid down either into the cylinder or through the carb to leak out into the airbox. This is amplified when people move the throttle back and forth as it actuates the accelerator pump, which squirts extra fuel into the carb as the throttle opens.

Obviously not a good situation to be in, if you get a backfire through the intake, you may suddenly have an engine fire on your hands. Preheating helps a lot in helping the gas evaporate into a combustible-enough mixture for the engine to fire over, as opposed to collecting in a dead-cold manifold. Not to mention thinning the oil enough so your starter can spin it up faster.

 

[Stewartb]

Primer lines direct fuel into the cylinders. Pumping the throttle is what causes fuel to drop out of the airbox. Cold starting can require a lot of fuel. Priming 6-8 strokes isn’t unheard of. And leaving the primer out to add fuel if the motor sputters allows one more squirt to keep it running. Resist adding fuel by pumping the throttle or you may experience an engine fire.

If you used the primer and found fuel it would be prudent to inspect for a cracked primer line.

12° is too cold to start without preheat. At that temp you’d have a very hard time providing enough fuel to make it start and stay running. Continental say preheat below 20°. Most owners do it at 30°. Cold starts are hard on the engine. You may have frosted the plugs at 12°. Game over until you preheat it.

 

[CT583]

How are y’all getting more than 3 shots of primer?
Mine gets really difficult to push in past 2 1/2 shots. 4 shots feels like I’m going to break something.
C182 P

 

[Stewartb]

Your primer should flow fuel. If you’re getting line pressure your mechanic needs to fix your priming system.

 

[Dan Thomas]

Hard to push implies clogged injectors, and they also won't be atomizing the fuel. Further, any fuel running out into the cowl is a fire hazard if the engine backfires.

Priming should be the LAST thing you do before cranking. And crank immediately, before that fuel runs down. Too many checklists look like the 182P's:



They tell you to prime, then turn on the master, then call clear, then find the ignition switch and start it. That can take more than several seconds, while the atomized fuel is busy condensing on the walls of the intake manifold and running down and out of the carb. Turn on the master and ignition, call clear, then prime and crank immediately. With new primer nozzles, and an overhauled primer, that engine will bark into life instantly. You'll also require less prime.

 

[LesGawlik]

I inject the last shot of prime as I crank. My Lyc fires up in less than a blade.

It wasn't always like that. Before I started that practice, I ran the battery down often because it just wouldn't fire.

 

[Clip4]

I would check the primer lines for a leak.