I was just checking to see which of my glow plugs are good and noticed that when applied to the glow igniter, the last turn of the coil does not ignite on all of my A3 plugs. Are they supposed to ignite along the whole length of the coil?

Well, glowing plugs is only half the matter. There is a coating (a plating) of a catylist, Platinum, on each of the coils. This is an absolute must for glow plugs to operate. They may glow, but if that coating is not there, well, they just won't work.

The only real way I know of checking them to see if they are any good is to fly with them. Not just start up the engine, but to fly with them. If you can fly, usually, the plating is ok.

CGr.

Ah! I just dealt with this problem, and I , too, thought that my plug was bad because the last turn of the element was not red (orange?)hot. Let me assure you that your plugs are good! It would seem that since the last turn of the element does not turn red hot that they are bad, but that is not the case.

That is definitely a qualified 'yes they are good'. If that platinum plating is burned away, and this happens, the plug will glow but it will not sustain flight.

CGr.

Another explaination. The end of the coil is attached to the body of the plug which acts like a heat sink bleeding off heat from the end of the coil.

Thanks for the help. I thought they were all bad and I knew I had some new ones. I should just leave them in the package.

The only real way to know if they are good or bad is to fly with them. If they work, they are ok. If one does not, throw it away no matter if it glows or not. Easy enough.

And yep, probably a good idea to keep them in the package to show they are new. But, as many RC'ers do, I keep one or two on the plug tool in the threaded holders provided. Easy access. However, I also put the old one back in the hole rather than throw it on the bench and leaving it there (forgetting about it). Then next time, I look at the plugs on the tool and wonder what ones are good and what ones are bad.

CGr.

Gee, and here I thought that I was the only one who did that!!!!

Ken

if the engine runs perfect how often do you change your glow plugs ? Once a year?

When the glow plug dies. As long as your engine is running well there is no reason to replace the glow plug. I have engines that have glow plugs that are easily 3 or 4 years old and they still run strong. Old saying comes in here..... "If it ain't broke, don't fix it"!!!!

Ken

Don't "fix" a problem that does not exist. If it runs perfect, leave it alone. When it stops running perfect, diagnose and fix the problem. Glow plugs can last several years.

<< Ken and I were typing at the same time >>