Jim Thomerson

There are two essential elements to starting Cox engines. (1) a hot battery, make the glowplug glow at least orange. (2) a head prime. How much varies with individual engine. How much crankcase prime is needed also varies with individual engines.

If there is no starter spring, there is: (3) after head prime, turn the prop backwards to vertical, attach battery, hit propeller forward with your gloved finger. Flipping a Cox engine is an exercise in frustration.

If you fool with your Cox engine a bit following the above principles, you will soon get one hit starts almost every time. Reliable is good!

rainedave

My Feedback: (1)

Good points, Jim. I would just add that in my experience any air leaks will create endless frustration unless remedied.

Falco250

I spray automotive throttle body cleaner through the needle valve barrel if the engine has not been operated in a while.

propbuster

My Feedback: (1)

I just picked up an old Cox Cessna 182 Skylane (to replace the one I flew like I hated it, and did at the time) with an engine that looks like it hadn't been started up in a decade. After a squirt of fuel in the cylinder and a few lubing up flips, it fired right up!! Now,,,,, the trick is to get it to run at the field (seems they never will for me!)

on pipe

I think this is a handy tip as the amount of castor needed to run these things is also a good plugger upper if they sit for long... I've seen it get plastic-like and cause sealing problems in the reeds even. Ross

Jim Thomerson

Just bumping this one up.

Hueydriver

I'm sure this isn't news to most but.....once the engine starts, but suffers at low RPM, a quick verical shake of the nose of the model will bring it up to speed.

Kirk

ptulmer

My Feedback: (5)

Jim, there is an excellent article on my site by Larry Renger called "Care and Feeding of a Small Engine". Given what they need, my Cox engines are the most reliable in my hangar. Better even than the big engines!

MJD

My Feedback: (1)

I never had problems with any of my Coxes beyond the little things that would be prevented by the usual level of maintenance or common sense. I guess having run them since about 1968 or so helps, but they never seemed to be much of a problem. Keep 'em clean, use the right fuel and prop, good glow power source, learn how to set a needle valve, and off you go. Mind you one engine that does not apply here is the Dragonfly, that tank system was just a piece of crap to begin with.

MJD

Hueydriver

Xlnt article by Larry....thanks ptulmer!

Kirk

Wayne C

I have to agree on the hot battery. I always use four D-Cells. I buy cheap batteries at the dollar store. When every thing else is right and a Cox won't start check the battery. I had a few old glow plugs that I thought were bad until I connected them to a powerful enough battery. The art of the prime is something that can be developed with time if you pay attention. My "favorite" reedy usually starts on the first or second flip.