I would think it would be from excessive vibration if they were
originally for fixed service in the yard.
Agreed.

A good way to check for vibration is to set a dish of water near the bulbs,
rev up the engine while you observe ripples on the surface of the water.

I'd bet you'll see signs of excessive vibration at various throttle
settings. This is bad news for a hot filament (as you already know).


--
(¯`·._.· £ãrrÿ ·._.·´¯)



"Leanne" wrote in message
...

"Tom Best" wrote in message
om...
I would appreciate some help with a 12 volt question.

I would think it would be from excessive vibration if they were
originally for fixed service in the yard.

Leanne