Thank You Wes !
Order placed
Thank You Wes !
I think .5 is a bit high, I typically read less than .2 on good plugs when you subtract the resistance in the meter leads. I’ve been thinking about this a lot and started comparing the wiring diagrams between brick and obs trucks. The obs trucks use a different gauge than the brick nose trucks, but use the same controller and glow plugs, so I don’t think there was much tuning being done with the wire gauge, or maybe there was and the change was to improve the cylcling of the controller? And they actually had a screw in controller that read coolant temp in the 6.9s, but that controller had more issues than the solid state controller. I don’t think it will cause a noticeable issue with extending the leads, but even if it does well take care of itThe brain in the controller reads the voltage drop across the z bar on top of the controller itself. That is how it's measuring the current flow to the glowplugs. I bet you can't even measure the resistance of the z bar with a regular meter.
Let's say the glowplugs when they are cold are .5 ohms. 12v divided by .5 ohms equals 24 amps per plug. 24x8=192 total amps from all 8 glowplugs. 192 amps x .032 ohms added resistance =6.144 volts dropped across the new added wire. Divide 6.144 by 8 =.768 volts per plug lost by the new added wire.
The thing of it is, the factory figured some voltage drop in the wiring. The picked their wiring sizes (which I think we can all agree is a little on the small side) and then calibrated the controller according to this standard wiring harness. So you can put wiring that is too large in there and run into the same problem as adding wiring of the same size.
I am not sure why they did not have a controller with a temp sensor screwed into the engine. It would measure the temp of the engine directly, not indirectly like it does by measuring the current draw of the glowplugs.
-28 yikes! Thanks again for testing this out, can I send you some different brand glow plugs and have you test them to see how they read differently from the zd9s?Finally got my new oscilloscope in, I used the negative wire from the power supply as the current sense resistor which is why I have a ton of noise but it worked, I captured a total of 7 seconds which is when the glowplug was fully orange.
The yellow trace is the voltage, you can see at ~8v the voltage stops instantly climbing and ramps up to the final 12v value, that’s caused by my power supply going into current limiting till the glow plug starts
drawing less amps, I can definitely say that this power supply can’t do 60A haha.
The bright blue trace is the current, ignore all the background blue as that’s just noise it’s picking up. At the peak it drew 46.56A and at the end it was drawing 16.8A.
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Do note that this isn’t very accurate for a real world application as this is just one glowplug and with a power supply that can pretty much hold it at 12V. I will try and do another measurement on my truck when the weather decides not to be -28C.
-28 yikes! Thanks again for testing this out, can I send you some different brand glow plugs and have you test them to see how they read differently from the zd9s?
I have no idea why you wouldn't have thrown them out.I may have an autolite and maybe a Bosch plug laying around if I didn’t throw them out,
Nice of you to make this harness available to all of us that struggle with the OEM glow plug harness and bullet ends.Greetings Oilburners! Today I am happy to announce another new product from Classic Diesel Designs, our manual glow plug conversion kits, and our replacement glow plug harness. Our conversion kits use an industrial 12v 200a (600a inrush) White Rodgers relay, which is mechanically rated for 100,000 uses (more info HERE). Here is a White Rodgers relay next to a stock 7.3 gp relay:
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This conversion kit replaces all of the stock wiring for the glow plugs, and relocates the relay next to the fender mounted starter solenoid, away from engine heat and vibration. Everything you need to make this conversion is included, all you will need to add are eight ZD9 glow plugs and a pushbutton of your choice mounted in the cab (rated for 5 amp minimum). All of the glow plug wiring is premade, wiring for the pushbutton and fuse tap is included along with installation instructions to help simplify the installation. This is a great upgrade for 83-86 6.9 owners who want to eliminate the notorious screw in controllers and is a good solution for those who want to turbo their na truck, but dont want to deal with modifying the stock harnesses to relocate the stock controller away from the turbo.
Our replacement glow plug harness keeps the 7.3 controller in its na location, but replaces the 20+ year old wiring and connectors with a harness with marine heat shrinked bullet connectors and hydraulically crimped relay connectors. Built to hold up to years of heat and vibration and to help get all those amps from your glow plug controller to your glow plugs reliably.
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For now until February 1st our replacement harnesses are $35 shipped within continental USA, and our manual glow plug conversion kits for $135 shipped. International shipping is available, depending on your location there may be a small additional shipping fee. As with all our products, there is a 10% discount for our military and emergency responders! Thank you again for your continued support here on OBN!
-Wes
So, Wes,I’m happy to offer it! All the updated pricing is here: https://www.oilburners.net/threads/glow-plug-solutions-from-classic-diesel-designs.84824/
The preorder sell ended Jan 31st. To make life leagues easier working on these trucks, get yourself a top side creeper. It will save what’s left of your back!