Glow plug failure modes?

rbargeron

Well-known member
Lifetime Member

Equipment
L5450, L48, L3250, L345 never enough attachments
Jul 6, 2015
1,157
227
63
western ma
My L345 main fuse was blown and I was surprised to find that the glow plug circuit had ZERO resistance! Isolating them I found one actually shorted to ground. I haven't taken it out yet, waiting get a new one. But the question is - how can a glow plug fail other than to just burn open? I've replaced glow plugs in cars that were just burned out (open).

The bad one is disconnected and no longer causing the short. I had replaced the main fuse twice, assuming short was in the starter circuit, but just kept blowing fuses when turning the starter switch (which powers the glow plugs in either active position.) Any ideas? Dick B.