Glow Plugs Burning Out Prematurely!

[Canadaeh]

It seems I am under the hod way too much changing glow plugs. Like tonight in the snow and wind!
Brief history:
-Bought van (L400) in Dec 2009
-Changed out plugs in June of 2010 (unfortunately HKT were in and I replaced with HKT)
-first week Jan 2011 Changed out and put in VSP plugs.
-first week of Feb 2011 one VSP is done at #2 position.
!!!

Each time I changed plugs was because the van went from starting without hesitation rain or shine, even in minus -28 to rough smoky shaky start. Each time I would check the plugs and 1 or 2 of 4 were not working.

So why the quick burn out.
During start up, Voltage meter reads 11.5 V for 7-8 seconds prior to turning key to turn over engine.
Then meter reads 13.8 V for approximately 2 minutes while the engine is running then drops to zero.

I am looking for ideas as to why the short lifespan of these glow plugs.

Should the relay be putting out 13.8 V for two minutes?

Plugs come out looking asymetricaly sooty. Some are rough and pitted in a very slight manner. All have CP-05 stamped on the body.

[Manitoba deli]

It is normal for them to stay on for a few minutes if the engine is cold. They will stay on for up to three minutes or until the coolant is 50C, which ever comes first. It maybe possible that your coolant sensor is faulty, and keeping them on even when the engine is warm. Could also be the glow plug controller malfunctioning and turning them on when the engine is running. I would suggest wiring an indicator light to the glowplug relay so you can see when or if they are coming on when they shouldn't be.

Jason

[Canadaeh]

That is a great idea, thanks Jason I will investigate.

Mike