What makes glow plugs go bad?

[phazertwo]

So I installed 8 brand spanking new motorcraft/beru (spelling?) in my truck exactly 1 year ago, and now I have two that are bad!!!! What causes this? I don't drive the truck that often so I really don't think that its because I cycle them too often.

TIA, and let me know if you have any GPs for sale!!

PZ

 

[Late_99_psd]

I've heard that too advanced timing can burn up glow plugs.

 

[phazertwo]

hmmm, I suppose that would make sense, I think my timing is a little advanced.

PZ

 

[BigRigTech]

Advanced timing with a stock GP controller could be an issue but with short burn time on Manual GP's I haven't burned one out in over a year and a half.

 

[phazertwo]

Advanced timing with a stock GP controller could be an issue but with short burn time on Manual GP's I haven't burned one out in over a year and a half.

Does the advanced timing only damage the plugs while they are running? I don't see how the stock GPC would be different than a push button set up?

PZ

 

[BigRigTech]

Does the advanced timing only damage the plugs while they are running? I don't see how the stock GPC would be different than a push button set up?

PZ

Burn time is the difference between manual and auto GP's, I tend to burn mine much less than a controller would.

 

[icanfixall]

Advanced timing or a manual switch held on too long will ruin glow plugs. If you have the solid state controller then I would be checking the timing. Also look closely at the engine main wire harness plug. See if there is anymelting of the plastic housing. If there is any corrosion it will change the plug timed for glow too. I just replaced the two yellow wires with one large speaker wire with multi strands in it. Its fed directly from the fender solenoid now. Be aware... The feed wire is hot all the time from the solenoid to the controller..

 

[Kevin 007]

With my manual GP's, I cycle for about 9 seconds, then off for a 3 or 4 seconds and then on for another 5 or 6 and it starts great. Havn't burnt a plug for about 3 years.....knock on wood!

 

[93cc7.3]

i have the same issue ron timed my truck a few weeks ago he said it was almost 14 degrees retarded i think ill replace my bad plugs and not turn on timing advance till the glow plugs shut down

 

[88beast]

the controler cycles after start to keep the motor running in some cases think 10 or lower
for my new ones im going 5 on 3 off 5 on as needed