Think I'm going to lose it

[Swede]

ok. I started to switch over to 12volt set up after I couldnt get it started 2yrs ago.(102 Well went to Steel Soldiers :: Military Vehicles Supersite For manual Glow plug start. Set up for it but before I heated up the plugs I figured I would make sure Fuel is still moving. Had a friend at the fuel filter to bleed it, went to start it and nothing, didnt try turning over. I am really close to going insane. No diesel genius here, but man it is down right annoying not being able to find the problem. I have a civy 6.2 right beside which i might try to use to get working. The only problem is the farthest from original i wanted to get was out of the 24v. Any way hope to hear some good news or ideas.. before i completely lose it .. i really miss driving this truck but diesel is becoming a pain in my ***... BTW if you live in PA and know what your doing, ill spring for the beer and try to cover travel expenses if you can get this beast moving...LOL

 

[kassim503]

try jumping the starter first.

Did you replace the starter relay when you went to 12V?

 

[Blood_of_Tyrants]

When he says "try jumping the starter" he means that you get under the truck and try shorting the fat battery terminal to the skinny solenoid terminal. A screwdriver is good for that. Be prepared (wear safety glasses) because if the starter and wiring is good, sparks will fly a bit.

If it cranks, you have electrical problems between the ignition switch and the starter relay. Probably the starter relay. Civvy trucks don't have them because they don't need to switch 24v to the starter solenoid.

 

[dmc-4359]

fwiw -

On a few occasions where I've needed to be in front of the engine and also turn it over to bleed the injector lines, I use a six foot long 16 gauge wire with alligator clips to clip onto the small solenoid signal post. I run that wire to a toggle switch and then, from the other side of the toggle switch, a wire to the positive battery post.

In my case, I rewired the starter circuit entirely and just need to be able to engage the starter for 20-30 seconds while I am tightening down some injector lines. In your case, you would be able to use the same $3 worth of parts to help identify where your 12v signal is getting lost to your solenoid.

The alligator clip is really easy to connect if you lay down in front of the truck and reach over the differential to the starter. When I'm done I just yank the wire free.

 

[Swede]

Ok Tryed to jump it nothing. Does the ignition have to be on to jump starter? So would that be the starter? I looked around in at the relay. Metered out and Im getting 12v. I made a jumper and tryed to jump red and purple and nothing. I am really not taking this to well. I dont think any problem ever pissed me off as bad as this truck.. but man I miss driving it...LOL Maybe Im just completely stupid man........

 

[dstang97]

I would put it back to 24v and do a doghead relay then report back. My opinion is that 12v conversion is a bad Idea. But for now bust out the multi meter and see if your getting power get a helping hand and have some one try starting it while you check for voltage.

 

[dmc-4359]

Depending on your circumstance, and assuming you have someone around you trust, you could also just check to see if you have 12v from the big post on the starter to a bare metal point on the block or even the nose cone of the starter. If you have 12v there, then you put the meter on the little post of the solenoid (still grounding to the block) and get the other guy to turn the key so the starter will engage from inside the truck to see if you get 12v at the little post. If you are getting 12 volts and nothing is happening, your issue is limited to your starter.


edit - dstang took the words right out of my fingers, I should type quicker (grin)

 

[saddamsnightmare]

March 27th, 2010.

Swede:

I'd say hang on and reflect a little bit before you go off the deep end. Essentially what you have done is taken the military modifications to the starter on the CUCV and probably gotten halfway to the civillian K version. I would agree with Dstang97, that the truck might have worked better as it was in the 24VDC original. Usually when a 24VDC starter doesn't want to work, it's one of three things: 1. Starter Switch is worn out, 2. Starter relay is worn out (the one, I presume, on the firewall), or 3. The Starter Solenoid on the starter is worn out. Trace your voltage path through the supply (fuse or battery side of the starter switch), output side of starter switch; input side of starter relay, output side of starter relay; and solenoid input and output and to starter terminals. Somewhere in this path you likely have a wire connected wrong, or one of the three major switching units is worn out. It can't be much harder then a civillian K series diesel of the same period, you just can't hook it up to a computer to tell you what's wrong, so you gotta substitute that computer up top of your neck and figure it out. A CUCV ain't rocket science and if you take the time to systematically track the wiring in the starter circuit, you should be good. Does a CUCV have a fusible link in the starter itself, if it does, your conversion from 24VDC to 12VDC will just about double the amperage on the input surge on starting, could that have gone? If you choose to convert it back to 24VDC, I would recommend Dr. Doghead's relay set up for military CUCV's as insurance against a run away starter motor.......
Think man, Think!

Cheers and good luck,

Kyle F. McGrogan

 

[markinnh]

Kinda new to the 24 volt thing, but have had 4 or 5 pickups with 6.2's over the years. The worst thing about em was crankin em fast enough to start em on the coldest mornings. The 24 volts solves that. Whay are you changing it?...12 volts off the front battery for jumping other 12 volt ers....huh?

 

[charlietango]

multi meter is your best friend man. do as the others suggested above and take the guess work out of it. I have had brand new starters out of the box broken. cant rule anything out. start with the easiest solution and work back to the harder stuff

 

[dmc-4359]

Kinda new to the 24 volt thing, but have had 4 or 5 pickups with 6.2's over the years. The worst thing about em was crankin em fast enough to start em on the coldest mornings. The 24 volts solves that. Whay are you changing it?...12 volts off the front battery for jumping other 12 volt ers....huh?

When I converted mine to 12 volts last year it had nothing to do with jumping off other people and everything to do with being able to get a jump start myself. Along those lines, 3.5 kw of cranking ability is 3.5kw of cranking ability regardless of how the voltage and current details work with each other to get there. I suspect the starting trouble with most conversions of this manner is due to a 25 year old electrical system that only contended with half the current needs a 12 volt configuration requires. Because of this, I ran a 2 gauge ground wire straight to one of the starter mount bolts from the negative battery terminal as well as using the 2 gauge hot wire that was already run to the positive terminal on the starter.

 

[ODdave]

ok, im not trying to be an ass........ but the I.B.E.W. logo is cracking me up....

 

[dstang97]

I was thinking the same thing.

 

[ODdave]

When I converted mine to 12 volts last year it had nothing to do with jumping off other people and everything to do with being able to get a jump start myself. Along those lines, 3.5 kw of cranking ability is 3.5kw of cranking ability regardless of how the voltage and current details work with each other to get there. I suspect the starting trouble with most conversions of this manner is due to a 25 year old electrical system that only contended with half the current needs a 12 volt configuration requires. Because of this, I ran a 2 gauge ground wire straight to one of the starter mount bolts from the negative battery terminal as well as using the 2 gauge hot wire that was already run to the positive terminal on the starter.

3.5 kw may be 3.5 kw but he is right, the 24 volt system deliveres the energy faster than a 12 volt system but will only last half as long. Delivering the energy faster spins the starter/engine faster alowing it to start easier.

 

[charlietango]

ok, im not trying to be an ass........ but the I.B.E.W. logo is cracking me up....

I just realized how ironic it was lol

 

[dmc-4359]

3.5 kw may be 3.5 kw but he is right, the 24 volt system deliveres the energy faster than a 12 volt system but will only last half as long. Delivering the energy faster spins the starter/engine faster alowing it to start easier.

That doesn't make sense to me. If I double the voltage, I should only need half the current to accomplish the same amount of work in a given period of time. If I double the voltage and supply the same amount of current, I have doubled the output power of the motor in question and the 24v starters are not rated at 7kw.

I think most people who are seeing a 12v converted engine turning over slower, do so because their electrical systems are inadequate for handling the doubled current requirements to effect the same amount of work per time. My truck cranks just as fast as it used to with the 24v setup, but only because I ran an extra wire to insure a circuit that can handle the extra current needs. I can also get a jump from any old character in the parking lot if I need it too.

 

[ODdave]

if im not mistaken voltage is the amount of force pushing the amps, amps being the amount of energy carried. i dont understand what is not to get. the more voltage you put to it the faster it is going to turn (the same motor on 12 volts DOSE NOT turn the same rpm as it would on 24volts) how do you think 0-90 volt dc variable speed controls work in machining equipment???????? where did you come up with 7kw?

sry just had to add this, have you ever took a light bulb and added more voltage to it to see what happens? it gets brighter, this is because of an increase in voltage not amperage. amps are drawn not pushed, you cannot "push" amps into something, you can push volts and increase the output. as you mentioned you can increase the "amp draw ability" by increasing the wire diameter, though you will never see the same crancking rpm as 24v you may see a slight increase due to the #4 "choking" the current down some.

 

[Sgt Hulka]

I have been incredibly happy with my 12v conversion. There's really very little to it and it's much easier to live with. Go to the Resources section and study the Roscommon Equipment guide. It's all in there step by step...

 

[Ken_86gt]

Removed to prevent further confusion on this issue.

 

[dmc-4359]

if im not mistaken voltage is the amount of force pushing the amps, amps being the amount of energy carried. i dont understand what is not to get. the more voltage you put to it the faster it is going to turn (the same motor on 12 volts DOSE NOT turn the same rpm as it would on 24volts) how do you think 0-90 volt dc variable speed controls work in machining equipment???????? where did you come up with 7kw?

sry just had to add this, have you ever took a light bulb and added more voltage to it to see what happens? it gets brighter, this is because of an increase in voltage not amperage. amps are drawn not pushed, you cannot "push" amps into something, you can push volts and increase the output. as you mentioned you can increase the "amp draw ability" by increasing the wire diameter, though you will never see the same crancking rpm as 24v you may see a slight increase due to the #4 "choking" the current down some.

You're right, voltage is pressure, amperage is volume. Horsepower, or watts, are derived values that are independent of any single aspect of a particular system. You absolutely can draw too much current and cause the voltage to drop. In this case, our system is how much work can a starter do in a given amount of time. We are adjusting the voltage and the current details but the amount of work that is able to be done is the same when the bendix gear hits the flywheel regardless of which one you have.

If I have a circuit that can handle 100 amps (high quality 4 gauge wire's max rating on its best day) without creating any significant resistance and I run it at 24v, I can effectively dump 2400 watts of goodness to some device if it will draw that without any issue. I can briefly over run this circuit with an additional 45 amps if the device draws but for every second I run the extra 45amps, I'm increasing the temperature of the wire which is increasing the resistance of the wire feeding the device...which requires even more current in order to maintain the 24v line pressure I'm running. In practice, it would take a good while to do this with just a 50% overrun on the wire specs. No voltage drop is likely within the 2-3 seconds needed to start a properly maintained 6.2.

The same circuit running at 12 volts, would require an additional 190 amps over the rated wire's 100 amp limit to deliver the identical 3.5kw the device will draw. The temperature of the wire will rise much faster and subsequently draw even more current much quicker than the 24v system. It would very easily begin to cause a voltage drop because the wiring simply cannot support the volume the starter needs in order to output 3.5kw to the flywheel. This voltage drop from the rated 12v the starter is designed for, translates to a slower cranking speed.

I have invested $15 in some 2 gauge wire and some wire lugs. I can run more than double what the stock system would handle on its best day with the nicest wiring in the world and I do not experience the voltage drop that causes the output to the flywheel to drop below 3.5kw. As a result, my engine turns over just as fast as anybody else's and fires up within 2-3 seconds no problem. I can also get a boost from some one in a parking lot if I need it.



as an aside;

My 7kw example made previously was a simple response to the statement that one is simply halving the time the power is available instead of halving the current necessary to effect the same amount of power. It was not meant to add any confusion, just to illustrate what I saw incorrect in the original statement I was replying to is all.