Hi guys,
The L200 I recently bought hasn't started well since I got it... it seemed like it was trying to start on only one cylinder (and it only has two, so that's not good!)... I assumed one glow plug was dead. Of course it was 60F when I bought it, so I could get it to start eventually... but now it's 38F here, and it won't start at all.
This week, I spent some time looking and finally found one glow plug ($48 after tax & shipping!!) at a dealer an hour and half away, and got it via UPS yesterday... I put it in today, and the tractor acts the same... still doesn't want to start... so I took the two glow plugs out, wired them up where I could see them, and for some reason, I can only get one to glow at a time.
At first, I didn't realize that the body of the glow plug that screws into the head is not the (-) ground of the plug... every other diesel I've ever worked on uses the body of the plug as the ground, and you just wire a positive to the top of the plug. But, in testing the glow plugs out of the head, I figured out the way these NGK's are designed, with the threaded body of the plug insulated from both the positive and negative parts of the plug... different!
I don't think the glow plugs in this tractor have been wired right for a long time... at least not for its last owner... but now I've got them wired with separate grounds and positives now, everything in parallel... and I still can only get one to glow at a time... it's almost as though the two glow plugs have different resistances, and only one is actually glowing... the other gets warm, but no glow.
This L200 has a glowplug indicator (resistive coil) in the dash... it glows bright after about 6-7 seconds... and from there, a #10 wire runs down to a big coil resistor that sits under the fuel tank... which starts to glow after about 20 seconds. From there, a #10 wire runs to the first glow plug, then jumps over to the second. The second glow plug has a #10 wire going to ground, on the head.
With everything wired up, and a fresh battery, I'm only reading about a volt and a half between the top of the glow plugs and ground, when the glow plug switch is on. I'm getting 12V to the upstream (dash) side of the big coil resistor. If I bypass the big coil resistor, and supply 12V to the + of the glow plugs, I can get the glow plugs to glow better, but I'm afraid they might burn out – and at $48 each, I don't want to burn any out. (!)
So... I've been scratching my head... I made sure all the wires from the coil resistor to the plugs and to ground were cleaned and good, and even got ridiculous at one point and used some #6 copper in parallel on the plugs, thinking the 40 year old, maybe #10 aluminum wire might be the culprit!
So my questions are... does anyone know exactly how these are supposed to be wired? Is only one plug supposed to be grounded, or is there a trick to stacking the washers on the top of the plug, to ground them that way?
Do the glow plugs have to be matched in impedance? It's almost as though all three of the plugs I have (I've got one spare now) have different impedances, so they each glow at a different rate. Does anyone know what the voltages are supposed to be at different points in this system... like before and after the big coil resistor? Am I making a mistake by wiring the grounds of these plugs in parallel? Any suggestions are welcome!!
Thanks,
-Norm.
The L200 I recently bought hasn't started well since I got it... it seemed like it was trying to start on only one cylinder (and it only has two, so that's not good!)... I assumed one glow plug was dead. Of course it was 60F when I bought it, so I could get it to start eventually... but now it's 38F here, and it won't start at all.
This week, I spent some time looking and finally found one glow plug ($48 after tax & shipping!!) at a dealer an hour and half away, and got it via UPS yesterday... I put it in today, and the tractor acts the same... still doesn't want to start... so I took the two glow plugs out, wired them up where I could see them, and for some reason, I can only get one to glow at a time.
At first, I didn't realize that the body of the glow plug that screws into the head is not the (-) ground of the plug... every other diesel I've ever worked on uses the body of the plug as the ground, and you just wire a positive to the top of the plug. But, in testing the glow plugs out of the head, I figured out the way these NGK's are designed, with the threaded body of the plug insulated from both the positive and negative parts of the plug... different!
I don't think the glow plugs in this tractor have been wired right for a long time... at least not for its last owner... but now I've got them wired with separate grounds and positives now, everything in parallel... and I still can only get one to glow at a time... it's almost as though the two glow plugs have different resistances, and only one is actually glowing... the other gets warm, but no glow.
This L200 has a glowplug indicator (resistive coil) in the dash... it glows bright after about 6-7 seconds... and from there, a #10 wire runs down to a big coil resistor that sits under the fuel tank... which starts to glow after about 20 seconds. From there, a #10 wire runs to the first glow plug, then jumps over to the second. The second glow plug has a #10 wire going to ground, on the head.
With everything wired up, and a fresh battery, I'm only reading about a volt and a half between the top of the glow plugs and ground, when the glow plug switch is on. I'm getting 12V to the upstream (dash) side of the big coil resistor. If I bypass the big coil resistor, and supply 12V to the + of the glow plugs, I can get the glow plugs to glow better, but I'm afraid they might burn out – and at $48 each, I don't want to burn any out. (!)
So... I've been scratching my head... I made sure all the wires from the coil resistor to the plugs and to ground were cleaned and good, and even got ridiculous at one point and used some #6 copper in parallel on the plugs, thinking the 40 year old, maybe #10 aluminum wire might be the culprit!
So my questions are... does anyone know exactly how these are supposed to be wired? Is only one plug supposed to be grounded, or is there a trick to stacking the washers on the top of the plug, to ground them that way?
Do the glow plugs have to be matched in impedance? It's almost as though all three of the plugs I have (I've got one spare now) have different impedances, so they each glow at a different rate. Does anyone know what the voltages are supposed to be at different points in this system... like before and after the big coil resistor? Am I making a mistake by wiring the grounds of these plugs in parallel? Any suggestions are welcome!!
Thanks,
-Norm.