earlwb

I remember that happening a couple of times when I used to do some pylon racing. It happened with some expensive high end glow plugs too. I have seen glow plugs do weird things over the years. Once when I was really big into pattern flying, I bought a couple of cards of glow plugs made by a major brand engine company, and every glow plug lasted just one flight. They denied there was a problem, but a few years later I found out that they had quietly changed the design and fixed the problem. But I never have bought any of their glow plugs since.  I have had a few plugs go bad, in that they still have continuity on the glow ignitor meter, but the engine won't run. I pull the plug and look at it and there isn't anything obvious that is wrong, it lights up good, it just won't fire up the engine. This tends to happen rarely, so that you forget about it for a while trying to figure out what the problem it. When in doubt I put in a new glow plug. I keep the old ones, almost news ones, etc. in a small box to use for test running engines. Usually when I test run engines, the running in process is hard on glow plugs and they tend to go bad fast like that.  I normally just buy Fox glow plugs and except for pylon racing, where I used some Rossi plugs, the Fox plugs have given me good service.