Glow plug lamp bypassed

[IdahoNative]

First, I very much appreciate this forum and those who have helped me thus far.

On my journey to restoring B7100D, I noticed my glow plug lamp is bypassed. It starts quickly (no winters in Florida) and the glow plugs are OEM and perhaps original. I have a secondary dash for parts with factory harness and the lamp is bypassed on it too. The coils in both lamps are shot.

Is it common to bypass these? I understand their purpose, BUT…Any reason I should wire up a new lamp? I’m thinking if it’s not broken….why fix it?

 

[ve9aa]

If it's bypassed and you use glowplugs (I do even in 90*F heat) then you are shortening the life of your GP's.
The lamp serves a dual purpose.

-An indicator
-A voltage drop for the glow plugs who generally require something less than 12.8V to run at peak performance.

If you absolutely NEVER use GP's then all is moot.

 

[Roadworthy]

Are these actually lamps or are they indicators? Older tractors used a coil of resistance wire to drop the tractor's nominal twelve volts to the 10.5 volts the glow plugs wanted to use. The ends of the wire would typically oxidize and not pass current to the glow plugs and were commonly bypassed. Of course this would shorten the life of your glow plugs and the excess current could overheat the wiring if the circuit was energized for too long. The other possibility is burning out the glow plug contact in your ignition switch. The addition of a relay in the circuit can prevent that.

 

[IdahoNative]

If it's bypassed and you use glowplugs (I do even in 90*F heat) then you are shortening the life of your GP's.
The lamp serves a dual purpose.

-An indicator
-A voltage drop for the glow plugs who generally require something less than 12.8V to run at peak performance.

If you absolutely NEVER use GP's then all is moot.

Are these actually lamps or are they indicators? Older tractors used a coil of resistance wire to drop the tractor's nominal twelve volts to the 10.5 volts the glow plugs wanted to use. The ends of the wire would typically oxidize and not pass current to the glow plugs and were commonly bypassed. Of course this would shorten the life of your glow plugs and the excess current could overheat the wiring if the circuit was energized for too long. The other possibility is burning out the glow plug contact in your ignition switch. The addition of a relay in the circuit can prevent that.

On my running tractor and the parts tractor, both are lamps with burned coils. It normally takes about 10-15 seconds for the plugs to heat up. I don’t think the previous owner did anything to the tractor, including change glow plugs. He used it a lot, but there’s no telling when someone bypassed the lamp. Given the corrosion, it looks like it’s been bypassed for a while.
I like your idea of a relay in the circuit. I imagine the trigger wire would be from Post 19 on the ign switch?

 

[Kenonf]

Hey Scott,
It is going to get cool enough you will want the glow plugs,
grab a Kubota one, the after market ones are a little spotty.
Ken

 

[IdahoNative]

Hey Scott,
It is going to get cool enough you will want the glow plugs,
grab a Kubota one, the after market ones are a little spotty.
Ken

Hey Ken! Thanks for the comment. The fenders are painted and the rear half is replacing mine this weekend. Thx again for selling the stuff at a great price!

 

[PoTreeBoy]

The nice thing about those indicators is they let you know your glow plugs are working. Since the current actually flows through that wire, if it glows your glow plugs are drawing current. There's no false positive like you can get with a simple indicator lamp.

 

[IdahoNative]

The nice thing about those indicators is they let you know your glow plugs are working. Since the current actually flows through that wire, if it glows your glow plugs are drawing current. There's no false positive like you can get with a simple indicator lamp.

I will replace the failed glow lamp. No more guessing on the fly if GP’s are working.

 

[Russell King]

On the glow plug circuit the indicator is in the circuit in the glow position but in the crank position the indicator is bypassed on my L185

You may want to see what the wiring diagram shows