M817 just arrived joy and pain

[highsiera]

Finally got the Dump up from AL and deliverred to our place up in the Northern Neck of VA. It was purchased non-running, but complete w/ good rubber. Hardly a steal, but I'm happy. Looked it over thurs day after we dropped it off the trailer, drained the gunk from the fuel filter can, replaced the rubber ends on the vent lines, checked the bats (doa) and checked the fuel selector valve (a few new hoses). Made a list for the weekend and headed home.

Drove up sat w/ 2 new group 31's and few other necessities with the hope and every intention of geting it running. Downloaded all the TM's and manuals onto a flash drive and packed the laptop too.

Hooked up the new bats, walked around once more, cleared the fuel can again, primed the intake etc. and hit the swtiches....here's what I found:

Bat On: only gauge responding is fuel, reading correct for both tanks. No buzzer, no volts.

Ignition: click at control box, nada @ starter.

Pulled the voltmeter out, 24 @ starter, 24 @ switch, 24 @ switch wire at starter.

Cleaned all the contacts on the starter wires, no love. Control box is new(er) Southern Auto (sp) type and looks like it was recently replaced.

Now I've read through all the tm's, including troubleshooting and really didn't help much. Fell back on personal experience and took a closer look at the starter. Pulled it out of the block, hooked wires back up to field bench test it and still nothing. It has the prestolite starter (ngc 250 cummins), tried to pull the solenoid off and couldn't, no interweb so I dropped it out and took it back home.

I went to the starter motor after assuming the control box was good based on a. it's relative newness, b. the fact i was getting volts at the start wire from the box in the start position.

When I got hone and searched posts I just have become more confused. The lack of the buzzer and bat gauges seems to point me towards a bad box, the volts at the switch wire point me to the starter.

Questions: 1. best way to bench test starter in a home workshop environment ? 2. Thoughts on why I have fuel gauge but no others? separate circuit away from control box?? 3. how the heck do you get the solenoid either off the starter body, or for that matter back in to the housing, sticks out about .25" and the stubby bolts won;t line up.

Any feedback is appreciated please . pics below, including bat terminal wiring, apolgize for the blury on those

 

[highsiera]

more pics, on bats pos term is on right, towards front of trk

 

[DaveP]

Need a better pic of your batt lead hook up. doesnt look rite but pics are not clear.

 

[highsiera]

sorry about the quality, I left the cables in the original orientation on the terminals for the main pos and neg, and deleted the short jumpers betw/ the 2 6v in each box. was rading 24v @ the slave recep. also

 

[mckeeranger]

sorry about the quality, I left the cables in the original orientation on the terminals for the main pos and neg, and deleted the short jumpers betw/ the 2 6v in each box. was rading 24v @ the slave recep. also

There should have been 2-12v in each box, for a total of 4-12v. 2 sets in series and parallel. That creates the 24v with twice the cranking power.

To run with 2-12v, leave out the cables marked 68-7, and connect the wire marked 6 to the terminal with the cables marked 48 and 49.

That may be what you did, but it's hard to tell in the pics.

Edit: to bench test the starter, I use a commercial 24v battery charger that has boosting capacity.

From TM 9-2320-260-20

 

[BadMastard]

Hey Highsiera,

Ok, not to be funny, but is there a chance your 24 volts was reversed? If so, would explain some of the odd readings. Second thought, for the starter bench testing, you can hook up your starter to ground of the 24v battery, CLAMP THE STARTER DOWN, and apply direct voltage to the terminals. You will probably get immediate turn, if not, then your starter may be kaput. I haven't seen your starter, so I can't tell you where the terminals are, but it's how I "hard" tested starters in the olden days when I had no test gear. Or take it down to the local NAPA, mine out here will test it for you. I'm a big fan of that way, so they can take the blame if they short it out.

If your starter tests good that way, it's power. Could be bad solenoid, so that's an easy (relatively) fix. Could be bad wiring. Electrical gremlins are the most fun to chase.

These are only my thoughts, and your mileage may differ. I suspect there are better experts on this site, I just happen to be awake.

BadMastard

 

[BadMastard]

Oops, see! someone with better knowledge beat me to it.

 

[DaveP]

looking at the pics again--- you really need to take a close look at how the batts are hooked up. from what you said , it appears the positive posts are hooked together?

 

[highsiera]

Thank you for the replies. Mckee, I'm not real good at schematics, but I think I understand what your saying. In simple terms, I removed the orginal 6v's, left the "long" battery cables attached to their original terminals (both pos and neg) and removed the very short cables and terminals that ran between the the two 6v in each box. the ones removed are covered in TM 209-2320-260-20, para 4-48, at the top of page 4-97, everything else was left in same arrangement as per the TM.
jumper from pos term on lh bat, to pos term on rh bat and starter cable hooked to same term on rh bat, negs are the similar, jumper from neg on rh bat to lh bat term, same term has cable to frame ground....

I will get better pics next week, promise

yes both pos itives are hooked together, pardon my ignorance (sincerely) when linking them together should it be pos to neg from one battery to the other?

 

[highsiera]

"the google" is pointing to me being an idiot.... i have themconnected parrallel as oposed to being in a series.

 

[DaveP]

"the google" is pointing to me being an idiot.... i have themconnected parrallel as oposed to being in a series.

well atleast you were able to inspect the starter up close.

 

[mckeeranger]

Here is a cleaner diagram:

Edit: I forgot to add the cold start circuit connection. You DO NOT want to send 24V to the cold start heater, it will probably burn out. The diagram has been updated.

 

[jimmcld]

If you had them in parallel, you could not be getting 24v. It does look like they are in parallel, and from what you have said, they are in parallel, but you also keep saying that you have 24v. Are you sure it's 24v, or is it 12v?

 

[highsiera]

I restopect, I do not trust the voltage readings on my $2 meter at all now. I do have the bats hooked up wrong. I plan on correcting that sat, reinstalling the starter, and hopefully bringing this thing to life. I will report back on sunday. It says "Private" under my handle for a reason, but there is a learning curve here...

 

[davidkroberts]

my m-818 is running 4 12v batteries but ive heard that they will start with 2 but keep in mind they were designed for 4 for a reason. Probably cold starting but oh well.

With your gauges being screwy and you saying the batteries were connected wrong thats probably the problem. Since you have the starter pulled you might as well run it to Napa and have them test it. Just as well its no more work anyway. Then you can atleast check that off the list.

Are you testing the volts with a multimeter or a 24v capable test light? I trust my multimeter allot more for electrical troubleshooting. And you might as well check your grounds and connections while your working in that area anyway.

I like the truck...... welcome to the madness

 

[highsiera]

will have the starter checked before re-installing it. way too heavy to do that one twice.

 

[dittle]

You may only be a private on this site but atleast you're listening to guys who have experience and following said advice. Keep it up and you'll be fine. Same can't be said about everyone who is just getting into the OD market.

 

[highsiera]

Thank you sir, The books are good, but learning from others experience is so much better in real world situations. I liken it to apprenticing in a trade. You read and learn theory, and then you work in the field with the master side by side actually doing it. that is the real teaching experience... wake up one day and your teaching the kid next to you. Brian

 

[crasheej]

YOu won't be able to get parts for the prestolit starter if it is broke. I done been down that road. So I hope it is just the batterys being hooked up wrong.

 

[highsiera]

Update: Starter is back together, tested resistance on coils and appears to be good. thank goodness, hear you on the prestolites . My father, the electrical engineer, is visiting, big help. heading up at to re-install, correct battery wiring, thank you so much for the diagram and get her running. fuel cannister cleaned out, filter was dried and blown out, all reinstalled carefully (waiting on new filters) system bled out also. will update on progress sunday.