12V Conversion Question

[EF-5]

I just bought my first M1008 for $2300. The odometer reads 39,000. The interior is in ridiculously nice condition, with no rust or tears in the seats or dashboard. All of the weather seals are good. It needs a good oil change, and for all the other fluids to be checked. I have some plans for it such as 700R4 swap, and bigger tires. However the first MOD on my list is the 12V conversion, followed by the doghead relay MOD.

My question is concerning the 12V starter. I am looking at three (Powerstrike, ACDelco, and Caltric). Is there anything about the "spline" and tooth count that I should take into consideration, or are the starters just a direct replacement?

The reason I asked is because I am following the instructions that everybody refers to. They are fairly straight forward, but at one part it mentions "additional splining may be necessary." Not sure what that means??

Any advice would be great! Thanks!

 

[ODFever]

My M1009 was converted to 12 v before I bought it. I had a few problems with the starter. To make a long and painful story short, I got really good at swapping out the starter. I got it down to 30 minutes from start to finish thanks to bad rebuilds. To answer your question, the 12 v is a direct replacement for the 24 v. The only difference is the 12 v is A LOT cheaper. Don't worry about the tooth count. The best rebuild that I got was from NAPA. Cost me around $250. Not sure what the 12 v converter instructions include but from my experience I had to replace the glow plugs and the glow plug relay. 12 v parts for the 6.2 L are far cheaper and readily accessible than 24 v.

Hope this helps!

 

[overkill375]

if the 24 volt works leave it alone IMHO. I have starters both 24 and 12 volt if you need one they are good used and priced right.

 

[Recovry4x4]

12V conversion is kind of a false process. The vehicle is already 12V but has the additional feature of 24V starting which greatly reduces the impact on wiring. It's more a matter of elimiating the 24V starting feature. The glow plug system is 12V and gets it's voltage stepped down from the 24V side via a resistor bank on the firewall. This is necessary for 24V slaving but you could also run them directly from a 12V source. Unless Andre the butcher has hacked up your wiring harness, I would think long and hard before elimiating the 24V feature of this truck. There is just not much to gain in my opinion but the bottom line is that it is your truck and you should do as you wish.

 

[boomer431]

If you convert to 12v you do not need to do the doghead relayswap. Just connect the purple wire to the purple/white wire and you are good to go.The original relay is there to switch a 12v signal from your ign switch to 24v to the starter solenoid.

 

[mistaken1]

If you do a 12V conversion follow the roscommon method as it works and is well documented.

http://www.roscommonequipmentcenter.com/news_notes/nn10.pdf

 

[EF-5]

Thanks guys for the response! I am following the roscommoneqipment link. That's what I was referring to, but could think of the name . I have a couple of reasons to do the conversion: air conditioning, spare alternator, auxiliary battery, simplicity, and parts are cheaper and more readily available. I hear it's hard to find a 24V starter, and a lot more expensive.

Boomer, is it as simple as that? So I can kill to birds with one stone huh. I can leave the original solenoid?

Thanks again.

 

[acesneights1]

AFAIK, The starter motor is the same from 12 to 24v. It's the solenoid that is different. You could probably change the solenoid.
I'm probably going to convert as well even though I really like the 24v start. My issue is I want to get rid f the V belts and use a serp belt setup from a 6.5 and I don't see any way to keep dual alts with serp belt. I considered using a series parallel switch to keep the 24v start. Old Macks used to use them and they worked well.

 

[dstang97]

Ewww. 12v and 700r4

 

[EF-5]

haha sorry dstang. Actually my transmission is already slipping real bad, so I guess this would be the time to make the swap.

I have another question. My gas gauge keeps floating like it can't make up its mind how much gas I have in the take. It occasionally reads about right, but 90% of the time its reading way more than I have. What could be the problem? Sensor? Bad grounding?

Any advice on how to run some diagnostics would be great !

 

[Barrman]

The -20 manual has a page or so dedicated to fuel gauge diagnosis. If it is going to the full side, then either the tank ground is bad, the wire to the tank is bad or the sendor is bad. Follow the procedures in the manual to narrow it down some more.

 

[EF-5]

Thanks! Can I get the manual from this site, or should I just goggle it? Also I want to double check something concerning the 700R4 swap. It doesn't matter what year that transmission is does it? Such as an 88 Silverado 700r4?

Thanks again!

 

[Warthog]

www.jatonkam35s.com

He has listed the CUCV manuals - Free to download

 

[boomer431]

The doghead relay mod is for the starter relay under the dash. This is a must do if you stay 24v because the relays have a high failure rate with bad consequences. The relay changes the 12v signal from the ignition switch to 24v to the starter solenoid. S0 if you are converting to a 12v starter you do not need the relay. Joining the two wires together just sends 12v from the ign switch to the starter solenoid. you will still need to do the rest of the 12v conversion as this is just for the starter relay.