Glow plug test

[tom brightbill]

This is new to me, but probably not to most others, but I accidentally found an additional test for glow plugs. When my normally sewing machine smooth K-77 instantly  started running in a surging manner then quit about 4 minutes into a flight I thought either plugged fuel line/NVA or glow plug.Weather was in the mid forties, so I headed for home. Since the plug is the easiest to check, I pulled it and hooked it to the battery. I glowed brightly. There appeared to be a trace of fuel on it so I blew on it to clear it. The plug immediately dropped in brightness to about half of what it showed before then regained it's former brightness. I tried it again, same result. And a third time---. A new one didn't dim at all. Long story short, I now have a new test for my plugs.

[frank williams]

Was the new plug the same brand and type?

[tom brightbill]

Yes, no problem with it.

[Steve Helmick]

It would be exciting to look at the element with the glowplug microscope that Mr. Bruce Perry uses, up in the frozen North country. Well, maybe not exciting, but interesting. Wondering if the element is broken but still making contact by sheer accident.

Bruce's glowplug inspection devise is a Radio Shack "Pocket Microscope" with a 1/4-32 hole tapped in the side of the clear plastic doo-dad. I need to do that to my identical pocket microscope. And would, if I had any glowplug problems that encouraged me enough.  Steve 

[frank williams]

Is your plug driver a simple battery or a system with "smart feedback"?  A simple battery or an Rcats type or glo-driver?

[tom brightbill]

Simple battery, fully charged, about 18 months old that I used for both plugs. Steve is probably right, about a failing or failed element. The point is, I just thought that it may be an item of help for others when questioning the condition of their plugs.

[Brian Hampton]

I had a similar problem once with my Enya 61CXLRS which usually was dead easy to start. This particular day it suddenly developed an enormous kick back and if I managed to get it past TDC the following blade came through so fast I couldn't escape being hit by it. I pulled the plug and hooked it up to the power panel where it flared like a supernova for an instant then cooled and flared again at around twice every second. So, plug or power panel? I tried another plug and all was well.

[fred krueger]

A fellow club member who used to be a Masters Class Pattern flier made this observation/recommendation.  "If your engine starts acting strange and you haven't changed a thing; replace the plug".
Plugs are probably the least expensive item in our hobby/sport.  Don't be cheap!