how long does a glow plug last, or what are the signs that one will need to be changed?

If an engine was running well, then suddenly stops running well or deadsticks for no other known reason - change the plug.

If an engine starts okay, but then drops in RPM or stalls when you remove the glow igniter - change the plug.

If you take the plug out and it looks damaged - change the plug.

If you take the plug out and put it in the glow charger and it doesn't glow - change the plug.

Brad

How long they last depends on a lot of things. When we did control line racing, we used a new plug every race. Flying control line stunt, I've been flying the same plug for a couple of years. There is variation among plugs of the same kind as well. One will last, and another won't. They need changing as stated above.

I have one plane that has 400+ flights, over 70 hours total flight time, that is still on the original glow plug in it. It's an OS 56 4-stroke with an OS "F" type glow plug.

Ken

Although i think we can saftly say dont count on this, MOST plugs dont get really that much time on them.

Why not? I only used 1 new glow plug last summer. If you don't run your engine too lean there is no reason in the world that they won't last for a long time. Another thing that can shorten glow plug life is leaving the glow driver on the plug for long periods. I'm not saying that glow plugs will last forever, but if somebody is going through glow plugs quickly there is probably a reason why.

Ken

I agree with Ken and Jim. A plug will last for years if you treat it right. How do you treat it right? By treating your engine right. Fly with the engine peaked out and expect to change plugs regularly but fly nicely rich and easy on the engine and the plug will last seemingly forever. One thing that's hard on plugs is leaving the ignitor on while running at full throttle because then you have both the normal catalytic action heating the plug plus the electrical power. Like Jim, with CL stunt and always running rich I simply never even think about having to change plugs.

Although it is true that it COULD last forever im sure you have bough glow plugs that lasted all of about 1 second (factory defect) as for tunning it does play a huge roll as to how lonjg the plug will last,

Now the glow ignitor in IDEAL situations you should be able to remove it right away and this will help the plug but if your fling in the winter you need to leave it on a little longer untill the engine warms up, no one in our club has found a different way of doing it you leave it on at addlie for a minute or so (not at full power this will destroy plugs)

Also engine break in CAN eat glow plugs if there is any alluminium residue it will destroy your plug

I've been waiting for a over a year with two 61FX's to change the #8 plugs. I run slightly rich, use after-run, etc. I don't think about it. I know some think this motor is over-priced, and over-weight, but,.... I don't bring tools to the field.

I had an OS-F plug in a Surpass 90 (Hype 3D) for over 3 years and only changed it because the pickup from idle was not as crisp as when the model/engine combo was new. With the new plug fitted the engine was back to its best.

This is off beat of this thread, but I was just browsing and saw Piroflip2 post. Not having any lady fliers in my neck of the woods, I just want to say how nice it is to see a lady enjoying this rather male dominated hobby.

Hopefully you will encourage others of the fairer sex to join in. Best wishes.

Karol