Humvee Starter / Flexplate Teeth

[jake20]

Could it possibly be the start switch? Mine doesn’t traverse all the way and I’m still waiting on Kascar’s batch of new ones to come in. I figured it likely wasn’t the issue since it’s only responsible for the solenoid, unless it’s causing hard to detect intermittent engagement?

The only reason I suspect a lightly engaged solenoid is because I saw the bendix ever so slightly retract/return to full engagement in that video I recorded, and the sound itself sounds like it could be intermittently spinning at a high frequency. (Also a very high chance I’m over analyzing this)

Last time it ran was very good, engine ran normally and made great power, crankshaft turns without binding when using a wrench, nothing weird about shutting it off besides the fact that that this issue basically got progressively worse the more times I started it.

 

[jake20]

Good news!!!!

I don’t know whether I should be excited or bothered LOL

I said screw it and stole the start switch off my friend’s truck.

It now started flawlessly!!

Ok so here is my theory:

I set the old switch to start-> it cranks like garbage. Ok so like I previously said I might’ve been over analyzing, I think I might have been analyzing it at the perfect depth lol

When it cranked like garbage, it sounded like the cranking was similar to the operation of a stepper motor, and not smooth/weak cranking.

Since the solenoid has 2 purposes:

1: kicking out the bendix

2: closing the contactor

I think we were getting enough current through the start switch to kick out the bendix, but not enough to make solid heavy contact against the contactor leads


Anyway, that’s my theory, I feel this issue was likely very rare, thank you everyone for your help.

On a side note, If anyone wants to buy a half taken apart but likely good starter motor, it’s up for grabs haha

Otherwise I was able to find the necessary rebuild components and might just rebuild it.

Apologies for less than desirable formatting, typing this on my phone while all excited Started 3 times in a row so far without issue.

 

[Mogman]

Well that is certainly possible, it would explain why the voltage was not dropping as much as I expected. Glad you got her going!

 

[jake20]

10 starts later and no issues. I guess that solves that mystery. In any case the voltage across the positive/negative leads on the starter drops to around ~22 while cranking, which seems like an appropriate drop for such a high current device, but it’s engaging and turning without any issues.

Now to get those new switches from kascar

 

[jake20]

Argh, the saga continues… I go to start the truck tonight and I hear a horrible high rpm grinding. I go to turn the crankshaft manually with a wrench, and I realize it’s not smooth and binding. Great.. feels like the bendix sticking on the flexplate.

I remove the inspection cover and what do you know.. bendix is stuck half way out. I try budging it back manually with a flat head, it’s stuck in a half engaged position and won’t move. It ate part of my flexplate teeth while it was at it, I’m guessing it couldn’t kick out fully either. Flexplate should still be fine as it’s not toooo bad but come on lol

Only thing I can imagine is something came loose in the starter causing it to bind, or the bendix is bad. It was working flawlessly for the last few weeks since I fixed my original issue.

Video:

 

[Mogman]

Does seem like that starter failed if the bendix will not retract, that bites!!

 

[jake20]

Ok some more discoveries. I just noticed that the starter is extremely hot. I drove the truck a few hours ago before this, i take it there is a chance the bendix was engaged while driving?

Does the EESS/Start Box/PCB have anything to do with starter engagement? Or is it strictly the ignition switch that triggers the solenoid? I’ve got an SSI box.

EDIT: measured the temp of the starter with a temp gun. It’s currently at 125 on the body and 140 on the bendix housing. That tells me that it got much much hotter if it was in fact stuck while driving around. Sounds like it’s pretty much seized if anything.

 

[jake20]

Ok final thought before putting it to rest for the night. I wonder if it could possibly be the start switch causing this again.

My initial testing and operation with this new starter were using my friend’s switch, which is what fixed my original issue. And everything was fine with his switch thus far. About 2 days ago I returned his switch as I had finally received my replacement switch. I’m not sure if this is a coincidence or not.

Technically speaking, the overrunning clutch should make quite a bit of racket if the bendix was remaining engaged I think.

 

[Milcommoguy]

Ok some more discoveries. I just noticed that the starter is extremely hot. I drove the truck a few hours ago before this, i take it there is a chance the bendix was engaged while driving?

Does the EESS/Start Box/PCB have anything to do with starter engagement? Or is it strictly the ignition switch that triggers the solenoid? I’ve got an SSI box.

EDIT: measured the temp of the starter with a temp gun. It’s currently at 125 on the body and 140 on the bendix housing. That tells me that it got much much hotter if it was in fact stuck while driving around. Sounds like it’s pretty much seized if anything.

Did you state keyed or standard military switch? Either way a fouled switch could hang in the start position and keep the solenoid engaged. On start, 24 volts goes straight thru box to starter solenoid coil. Any box if water damaged can have shorts and failure point. Not seeing it is hard to say. Your SSI box electronics does not process the start signal.

Flex plates have been known to crack... and in such a way that may not run parallel to the pinion. When trying to disengage, pinion get bound up. One of the pictures I saw, had a couple of chewed up teeth. If mine, and another no fun day...the ring gear / flex plate would have been replace. IMO.

This can be very frustrating and $$$$. Need to eliminate the above switching / mechanical issues if present. Any further testing, I WOULD use a remote start test button, right on the solenoid with my eyes and ears on the problem, Bright light too.

Don't need a old computer to start an old truck. We understand the start box at Camoteksystems.com CAMO

 

[Maxjeep1]

Did you state keyed or standard military switch? Either way a fouled switch could hang in the start position and keep the solenoid engaged. On start, 24 volts goes straight thru box to starter solenoid coil. Any box if water damaged can have shorts and failure point. Not seeing it is hard to say. Your SSI box electronics does not process the start signal.

Flex plates have been known to crack... and in such a way that may not run parallel to the pinion. When trying to disengage, pinion get bound up. One of the pictures I saw, had a couple of chewed up teeth. If mine, and another no fun day...the ring gear / flex plate would have been replace. IMO.

This can be very frustrating and $$$$. Need to eliminate the above switching / mechanical issues if present. Any further testing, I WOULD use a remote start test button, right on the solenoid with my eyes and ears on the problem, Bright light too.

Don't need a old computer to start an old truck. We understand the start box at Camoteksystems.com CAMO

If my truck ever drives I want those fancy turn signals!

 

[Milcommoguy]

If my truck ever drives I want those fancy turn signals!

You got two trucks? Need one kit for each rig. In Stock NOW. CAMO

 

[Maxjeep1]

You got two trucks? Need one kit for each rig. In Stock NOW. CAMO

I only care if one gets hit! Lol

 

[jake20]

Did you state keyed or standard military switch? Either way a fouled switch could hang in the start position and keep the solenoid engaged. On start, 24 volts goes straight thru box to starter solenoid coil. Any box if water damaged can have shorts and failure point. Not seeing it is hard to say. Your SSI box electronics does not process the start signal.

Flex plates have been known to crack... and in such a way that may not run parallel to the pinion. When trying to disengage, pinion get bound up. One of the pictures I saw, had a couple of chewed up teeth. If mine, and another no fun day...the ring gear / flex plate would have been replace. IMO.

This can be very frustrating and $$$$. Need to eliminate the above switching / mechanical issues if present. Any further testing, I WOULD use a remote start test button, right on the solenoid with my eyes and ears on the problem, Bright light too.

Don't need a old computer to start an old truck. We understand the start box at Camoteksystems.com CAMO

Hey Camo,

Was actually going to give you a call on Monday, I’ve seen your box before and figured I’d get one if mine ever bit the dust.

A brief history on my start switch dealings:

Original switch: started the truck fine up until a few weeks ago when I started this thread. It never fully turned to “start” but seemed to work

New switch 1 from Kascar: wrong alignment keyway position

New switch 2 from Kascar: I put the switch into “start”, heard something snap inside of it, and then it wouldn’t come out of “start”. Off the truck of course, would be really bad if it were on the truck

Original switch off friend’s truck: Operated perfectly and no issues that I knew of

New switch 3 from Mac Motors: The current one I’m dealing with and not sure of its status. It turns fine, but for some reason the lever screw controls how much friction there is when turning the switch. No other switch I’ve dealt with has been that way

New switch 4 from Kascar: currently still pending arrival, they’ve been back ordered


All of these are the standard military switch, manufacturers unknown. I’ve read enough about the keyed ones to avoid them.


What I’ve learned: start switches for these things are elusive little gremlins that don’t properly pass angry pixies across the wire

I don’t want to drop the transmission and replace the flex plate to end up back at the same place grinding more teeth either, so here are my thoughts

1: replace the starter again since this one is clearly cooked

2: leave the dust/inspection cover off the truck for a while

3: manually verify each start and visually check that the bendix still isn’t engaged. I’ve got a mirror and a flashlight, should be easy enough

4: compare between my friend’s start switch and the one I just put in, and then deduce what’s happening. Check startups from both switches for at least a week


Not very scientific but it makes sense to me I suppose

 

[Maxjeep1]

Grounding issues? Can’t imagine so many bad switches from multiple suppliers! You have an issue that you have yet to find.

 

[jake20]

Grounding issues? Can’t imagine so many bad switches from multiple suppliers! You have an issue that you have yet to find.

It’s possible, but those 2 switches from kascar I never actually installed in my truck, since they were either the wrong orientation or not turning properly. I’ve also got that supplemental grounding harness from kascar that I haven’t installed yet, might as well put it in at this point.

This truck likes to tease me with random discoveries lol

 

[Maxjeep1]

It’s possible, but those 2 switches from kascar I never actually installed in my truck, since they were either the wrong orientation or not turning properly. I’ve also got that supplemental grounding harness from kascar that I haven’t installed yet, might as well put it in at this point.

This truck likes to tease me with random discoveries lol

I understand, grounds are so important and can cause many issues…. Batteries are equally important! This is weird system like nothing I have ever seen

 

[jake20]

Yea I’m gonna do some testing tomorrow and trace some grounds for sanity. Definitely a large recurring theme with these.

 

[Maxjeep1]

Yea I’m gonna do some testing tomorrow and trace some grounds for sanity. Definitely a large recurring theme with these.

They are like a problem child. Just when you feel like they are ok they show you something that you can’t believe

 

[Milcommoguy]

Hey Camo,

Was actually going to give you a call on Monday, I’ve seen your box before and figured I’d get one if mine ever bit the dust.

A brief history on my start switch dealings:

Original switch: started the truck fine up until a few weeks ago when I started this thread. It never fully turned to “start” but seemed to work

New switch 1 from Kascar: wrong alignment keyway position

New switch 2 from Kascar: I put the switch into “start”, heard something snap inside of it, and then it wouldn’t come out of “start”. Off the truck of course, would be really bad if it were on the truck

Original switch off friend’s truck: Operated perfectly and no issues that I knew of

New switch 3 from Mac Motors: The current one I’m dealing with and not sure of its status. It turns fine, but for some reason the lever screw controls how much friction there is when turning the switch. No other switch I’ve dealt with has been that way

New switch 4 from Kascar: currently still pending arrival, they’ve been back ordered


All of these are the standard military switch, manufacturers unknown. I’ve read enough about the keyed ones to avoid them.


What I’ve learned: start switches for these things are elusive little gremlins that don’t properly pass angry pixies across the wire

I don’t want to drop the transmission and replace the flex plate to end up back at the same place grinding more teeth either, so here are my thoughts

1: replace the starter again since this one is clearly cooked

2: leave the dust/inspection cover off the truck for a while

3: manually verify each start and visually check that the bendix still isn’t engaged. I’ve got a mirror and a flashlight, should be easy enough

4: compare between my friend’s start switch and the one I just put in, and then deduce what’s happening. Check startups from both switches for at least a week


Not very scientific but it makes sense to me I suppose

The switch is very important. 20 Amp rating on the RUN and 20 Amp on the start WITH 70 Amp inductive. Be very careful of knock-off sales. One way to tell is the plating. If it is shinny like polished brass...likely bad news. 75 clams for the real deal. See spec sheet.

Keyed option wired from general OTC automotive replacements do not meet current handling. Typically 5 Amp run and start on the ones sent to me for evaluation after failure. Even Cole Hersse and Pollack fall short on ratings.

My test would use the remote start button (properly connected to solenoid) Test to rule out components up stream. Could work it the other way too.

The Start circuit just applies 24 volts to solenoid. Should be straight forward. Check with multi-meter too.

Are you getting a solid starter engagement or does it chatter?



Going round and round, CAMO

 

[jake20]

When I originally opened this thread, the engagement was very chattery rotation but bendix fully engaged. That’s with my original switch that never fully turned to start but worked for a while. Stealing the switch off my friend’s truck solved it, my theory was intermittent engagement to the solenoid.


By remote start switch, do you mean a commercial one for regular automotive applications? I take it voltage rating shouldn’t really matter?

The switch I got from Mac Motors is definitely shiny to me at least, my original is very dull but also from just being in use. But it was clearly never shiny to begin with. Can see it in the pics.