Runaway starter

[House56]

At this point, I don't think shooting the parts cannon at it is the right thing to do without a bit more diagnostic work. Can you check the starter itself with a multimeter, placing the red probe on the big terminal that leads to the bus bars on the firewall and the neg probe on the case of the starter or the transmission? With the ignition cylinder in the on and off positions would help us identify whether or not your relay mod might have an issue. If it's getting 24v to that terminal with the key in on and not start, then you would want to check the relay you purchased and installed in the dash. If it does not have power with the key in the on position, buddy crank it a couple times over so you can establish power in start, then have buddy turn back to on, then back to off. You'll want to check to see if you still have power once buddy turns back to run for a second before he hits off. If you do have power there in run after start, then you will want to check your relay mod.

EDIT: The small terminal on the starter solenoid as well. That will help establish if the electro-magicals in the solenoid are turning off when they are commanded to by turning the key back. If there is still power there once you turn the key back to run, you'll probably want to look into getting a replacement solenoid or starter back from where you got this one.

Thank you for the advice. I’ll check these things tomorrow after work and report back

 

[cucvrus]

When I try starting it and it continues to crank it doesn’t sound crisp or easy at all. It’s a shreel noise that makes you grit your teeth and pray nothing is about to snap in half.
After hearing that description and giving it some thought you may have a bad ring gear. It could be deformed and ground away at a few spots. The engine always stops at the same 3 or 4 spots. Starter engagement takes place in the same 3 or 4 spots every time. Check you ring gear/flex plate. Take a few pictures and post them. Changing the flex plate does not require removal of the entire transmission. But it is a very easy job I have done many times. And I did mine on a cement floor and in the grass. Check that flex plate and report back. A flywheel tool is helpful to spin the flywheel. Good Luck. Be Safe. I seen this tool on eBay for $65.. That is a good price. It is a very helpful tool all around for the CUCV mechanic.

 

[House56]

When I try starting it and it continues to crank it doesn’t sound crisp or easy at all. It’s a shreel noise that makes you grit your teeth and pray nothing is about to snap in half.
After hearing that description and giving it some thought you may have a bad ring gear. It could be deformed and ground away at a few spots. The engine always stops at the same 3 or 4 spots. Starter engagement takes place in the same 3 or 4 spots every time. Check you ring gear/flex plate. Take a few pictures and post them. Changing the flex plate does not require removal of the entire transmission. But it is a very easy job I have done many times. And I did mine on a cement floor and in the grass. Check that flex plate and report back. A flywheel tool is helpful to spin the flywheel. Good Luck. Be Safe. I seen this tool on eBay for $65.. That is a good price. View attachment 801051It is a very helpful tool all around for the CUCV mechanic.

Okay I’ll check when I get home from work. So should I remove the bell housing plate on the bottom to view the ring gear and flex plate together? I’m still confused as to what’s causing this thing to run on until I turn the key to the off position. It has me baffled

 

[cucvrus]

To look at ring gear/flex plate you need to remove the bottom cover. As to why it is staying engaged I suspect you have issues in the wiring. If it gets stuck out in the gear it could be the starter. I know nothing about the current condition of anything on your vehicle. It may be simple. It could also be complex. Very hard to help and diagnose sight unseen. Guessing game at this point. Good Luck.

 

[House56]

To look at ring gear/flex plate you need to remove the bottom cover. As to why it is staying engaged I suspect you have issues in the wiring. If it gets stuck out in the gear it could be the starter. I know nothing about the current condition of anything on your vehicle. It may be simple. It could also be complex. Very hard to help and diagnose sight unseen. Guessing game at this point. Good Luck.

Quick question while I’m trouble shooting. Is this dog head relay mod supposed to have 24v coming to it through the red wire?

 

[v12venator]

Yes, the red is supposed to be 24v, the two smaller ones pass 12v to close the connection to the two larger terminals to pass 24v through to the starter solenoid.

 

[House56]

Yes, the red is supposed to be 24v, the two smaller ones pass 12v to close the connection to the two larger terminals to pass 24v through to the starter solenoid.

Okay so I just removed the starter but left it hooked up. Had a buddy crank the key over to start and then let the key return to its resting position and boom no starter run on. This is telling me the whole electrical starting circuit is correct. Am I right in thinking this way? I’m thinking the ring gear is getting locked up with the flywheel make it stay engaged. I’ve never shimmed a starter before do you guys have any advice

 

[v12venator]

There's a Dorman HELP! shim pack available from AutoZone that should help you out. What you'll want to do is remove the bottom inspection cover for the transmission bell housing to the bottom of the engine, add your shim pack starting around about 70 thousandths of an inch to see where your Bendix gear in the starter extends and retracts. Once you shim enough to get your Bendix gear to not get caught in the ring gear, then you'll know that you're shimmed enough to save your starter once the engine is running. You'll have to do this by buddy cranking the engine or getting the remote crank switch if you're doing this alone.

 

[House56]

There's a Dorman HELP! shim pack available from AutoZone that should help you out. What you'll want to do is remove the bottom inspection cover for the transmission bell housing to the bottom of the engine, add your shim pack starting around about 70 thousandths of an inch to see where your Bendix gear in the starter extends and retracts. Once you shim enough to get your Bendix gear to not get caught in the ring gear, then you'll know that you're shimmed enough to save your starter once the engine is running. You'll have to do this by buddy cranking the engine or getting the remote crank switch if you're doing this alone.

Awesome thanks so much for the help. I’ll pick up the shims and let you know when she’s rolling down the road again! Also one more question I had is where can I get new bolts for my starter. I used the old ones and after some reading I found out they’re a one time use kind of thing

 

[sneekyeye]

As long as they are the correct knurled bolts, just use them and torque them down correctly. It is wildly uncommon that they are replaced for anything other than breaking off in the block. They are not torque to yield bolts.

 

[cucvrus]

I agree with the use the starter bolts over. And honestly I seldom torque starter bolts. After doing things so long I have mind to know what tight is and what over tight is. I torque head bolts and other fasteners without fail. Loose starter bolts will break and starters without the correct shim or support brace in place will break. If the flywheel/flex plate has a bad spot change it. The constant pushing back and for the from uneven engagement will stress and break the bolts. Do it right the first time. Good Luck. Shims can be made if you can't find them. Thin metal and evenly shimmed. Be Safe.

 

[GreggVA]

I had a similar issue and found this thread really helpful.

doghead starter relay mod rebuilt gear reduction starter run away

Have couple questions. I done the doghead starter relay mod about 3 weeks ago and at that time i had my old direct drive starter in it. The relay would start the old starter fine but the old starter needed replaced as it was never shimmed and was sticking every now and then. I got a rebuilt 24v...

www.steelsoldiers.com

 

[House56]

I had a similar issue and found this thread really helpful.

doghead starter relay mod rebuilt gear reduction starter run away

Have couple questions. I done the doghead starter relay mod about 3 weeks ago and at that time i had my old direct drive starter in it. The relay would start the old starter fine but the old starter needed replaced as it was never shimmed and was sticking every now and then. I got a rebuilt 24v...

www.steelsoldiers.com

She’s alive!! I ordered new starter bolts last week and they finally came in today. I installed it with one shim and tried to crank it over only to be let down because it did the same thing. I removed it again and placed two more shims in it and gave that a try. Annnddddd boom nice crisp starter engagement and disengagement leaving me with the sweet sound of my truck running again! So in total I used 3 1mm shims and that seemed to do the trick. Thank you all for all your help and advice. I couldn’t have done it without you guys!