Glow plug voltage question. TM is giving mixed signals

[River Rat Matt]

Everything I've read about the CUCV glow plug voltage tells me I should have 12v plugs. But my TM is saying 6v. What is right? I get no volts right now and I'm just going to run a manual solenoid and switch (ie tractor).

 

[87cr250r]

Use 10.5V rated glow plugs for your CUCV. AC Delco 60G is the correct number. Don't run other brands. The CUCV setup is hard on plugs and the Delcos don't swell up when they fail.

The glow plugs relay is run by the ignition circuit and uses a 12v coil. Do not use a grounded relay such as a Ford starter relay despite their similar appearance.

The glow plugs relay switches 24V. This goes through your resistor on your firewall. If all 8 glow plugs are in good condition they will be supplied with 10.5V. If you have a bad glow plugs the supply voltage will be higher. If you have a bad glow plug and don't catch it (you can tell by watching the volt meter on the dash) you will have 8 bad glow plugs within a few starts. As each glow plug burns out the voltage applied increases which causes the remaining glow plugs to burn shortly after.

Having daily driven a CUCV for quite a few years, the glow plug system is mostly reliable. I think I had a total burnout incident once in that time and caught it a second time with just two plugs out.

If you use a grounded relay on the firewall you'll smoke the transistor in your glow plug controller. Don't do that.

 

[Barrman]

What manual is that? I don’t think I have seen that passage before.

 

[River Rat Matt]

What manual is that? I don’t think I have seen that passage before.

Thanks for the input, but I found the bulk of my problems. I have a bad crank or rod bearing that's holding rotation back. Running 2 x 1150 amp batteries (parallel for 12v on a 12v starter, and i killed 2 starters. Time to pull the motor and see what's going on.

BTW: I pulled the glow plugs and they're all 10.5v.

 

[87cr250r]

You can drop the pan without pulling the motor, fairly easy. Rods can get a wiggle test. Mains you'll have to drop a cap. Have you tried rolling the engine with a wrench on crank front bolt?

The 28MT was the better starter available for the engine.

28MT™ Medium Duty Gear Reduction Starter | Delco Remy

The 28MT is a gear reduction design available in 12 and 24 volt for medium duty engine applications up to 6.5 liter.

www.delcoremy.com

 

[River Rat Matt]

You can drop the pan without pulling the motor, fairly easy. Rods can get a wiggle test. Mains you'll have to drop a cap. Have you tried rolling the engine with a wrench on crank front bolt?

The 28MT was the better starter available for the engine.

28MT™ Medium Duty Gear Reduction Starter | Delco Remy

The 28MT is a gear reduction design available in 12 and 24 volt for medium duty engine applications up to 6.5 liter.

www.delcoremy.com

I turned it with a wrench 2 full revolutions. It was pretty stiff even between compressions. It burned 2 starters trying to start it. Never turning the starter more than 4 seconds.

I didn't think about dropping the pan in the truck. Thanks for the reminder.

 

[Keith_J]

What manual is that? I don’t think I have seen that passage before.

GM manual which has been converted to a PDF, I found it under file name GM_STG_16015_05_1C_1987_The_6.2_Liter_Diesel_Engine.pdf
Good manual which includes CUCV info as the D truck series.

 

[Keith_J]

Everything I've read about the CUCV glow plug voltage tells me I should have 12v plugs. But my TM is saying 6v. What is right? I get no volts right now and I'm just going to run a manual solenoid and switch (ie tractor).

That is not the TM, that is a GM shop manual, it has CUCV info listed under the D truck series, that is the GM term for the CUCV. Completely different from civy series.

TMs start with TM. Specifically, TM 9-2320-289-nn. The level of the manual, nn, is who it is written for and what it contains. The -10 is the operators or drivers manual. -20 is unit maintenance like oil and filter changes, belts, hoses, fuel pump and diagnostic procedures. -34 is full repair, engine overhaul.
Parts are found in the -20P and -34P. Naturally, -20P has parts authorized for -20 service so you won't find piston rings except in the -34P.

 

[Barrman]

Thanks Keith. I do have that manual but either never made it to section D or lost my mental image of it.

 

[Keith_J]

Thanks Keith. I do have that manual but either never made it to section D or lost my mental image of it.

It has that same effect on me too. Much safer than Ambien, no side effects.