Humvee Starter / Flexplate Teeth

[Mogman]

Everything else aside, if that bendix cannot even be pushed back at this point you have a mechanical issue with the starter.

 

[jake20]

Everything else aside, if that bendix cannot even be pushed back at this point you have a mechanical issue with the starter.

Yep, yanking it soon and will see what my options are with it on Monday. At this point I’m just curious to see if it’s the starter, switch, or something else to blame heh

 

[Mogman]

BTW which one did you go with, the new one or the rebuilt one?

 

[jake20]

Went with the rebuilt, date tag indicated it was fresh too, done in May this year. Now I’ve got a worn down probably working starter and a cooked starter haha

 

[jake20]

This is just sad lol

 

[jake20]

It's the switch!!!!!!

I can say with 95-99% confidence now that the switches I have been receiving are all garbage. I yanked the starter, did a battery of tests on it, and then did some testing with different switches installed onto the truck.

So here's what I did.

Test 1 (Starter Solenoid Bendix/Contactor Actuation Voltage):

I needed to confirm my initial suspicions on solenoid engagement voltage, and see how the solenoid acts when undervolted. My theory was that it was getting enough voltage to kick out the bendix to tickle the flexplate, but not enough voltage to close the contactor and drive the armature.

I hooked up a multimeter in continuity mode to the contactor leads on the starter. I set up a bench power supply at 16V and closed the solenoid. As expected, fork moves and bendix tries to engage (albeit seized in this case), but no continuity on the contactor leads. It was not until 22V that both the bendix and the contactor are in their proper positions. In any case, the solenoid is acting exactly how I figured and expected it to (it's not just either on or off, but it can be somewhere in between when undervolted)

Video:

For the following tests, the start switches were installed in the truck, multimeter set to DC Volts, negative lead on the starter ground cable, positive lead on the solenoid positive wire

Test 2 (New Mac Motors Switch):

Voltages based on switch position:

Off: ~13V
Run: ~16V
Start: ~25V

Video:

Test 3 (Original HMMWV Switch Stolen from Friend's Truck):

Voltages based on switch position:

Off: ~0V
Run: ~0V
Start: ~25V

Video:

This tells me with almost absolute confidence that swapping for the new switch caused the starter to get stuck engaged in the flexplate, but not engaged enough to drive itself off voltage from the contactor closing.

Sad to see a starter fall victim to a faulty switch, but at least now I know this much more about the start system on these

 

[Milcommoguy]

It's the switch!!!!!!

I can say with 95-99% confidence now that the switches I have been receiving are all garbage. I yanked the starter, did a battery of tests on it, and then did some testing with different switches installed onto the truck.

So here's what I did.

Test 1 (Starter Solenoid Bendix/Contactor Actuation Voltage):

I needed to confirm my initial suspicions on solenoid engagement voltage, and see how the solenoid acts when undervolted. My theory was that it was getting enough voltage to kick out the bendix to tickle the flexplate, but not enough voltage to close the contactor and drive the armature.

I hooked up a multimeter in continuity mode to the contactor leads on the starter. I set up a bench power supply at 16V and closed the solenoid. As expected, fork moves and bendix tries to engage (albeit seized in this case), but no continuity on the contactor leads. It was not until 22V that both the bendix and the contactor are in their proper positions. In any case, the solenoid is acting exactly how I figured and expected it to (it's not just either on or off, but it can be somewhere in between when undervolted)

Video:

For the following tests, the start switches were installed in the truck, multimeter set to DC Volts, negative lead on the starter ground cable, positive lead on the solenoid positive wire

Test 2 (New Mac Motors Switch):

Voltages based on switch position:

Off: ~13V
Run: ~16V
Start: ~25V

Video:

Test 3 (Original HMMWV Switch Stolen from Friend's Truck):

Voltages based on switch position:

Off: ~0V
Run: ~0V
Start: ~25V

Video:

This tells me with almost absolute confidence that swapping for the new switch caused the starter to get stuck engaged in the flexplate, but not engaged enough to drive itself off voltage from the contactor closing.

Sad to see a starter fall victim to a faulty switch, but at least now I know this much more about the start system on these

Trying to follow the data and test points. The ONLY time voltage should appear at the solenoid is during the start position with the solenoid being the load.

It was suggested to use a "test remote start button" at the starter to eliminate the musical chairs with switches. Might be where I got lost...lol

There can not be any voltage (sneek, leakage, alien) when returning to RUN at the solenoid control connection on the starter.

Strap starter down and bench test for effect or have the shop. Might be OK or one can cancel the gym subscription.

Up, down up down,,. in out, CAMO

Re-watched the video. The 16 volts is with a load (solenoid coil) in place??

 

[Mogman]

I think what he was eluding to was that the cheap switch was partially energizing the starter all the time which caused at least the second starter to fail as it was engaging or at least trying to engage the bendix all of the time.
The second starter is now damaged, no switch is going to help it.

 

[jake20]

Basically, the new switch I installed was still sending 13-16 volts to the solenoid positive wire even when in the off and run positions. The one I stole off my friend’s truck was sending 0 volts in the off and run position, as it should be like you stated.

So essentially with the new switch from Mac Motors, the truck would start fine, starter motor would disengage, but the bendix would remain partially engaged into the flexplate gear due to the 16V in the run position, thus the starter was being driven by the engine and bendix seized itself onto the shaft.

I’d try the remote start button too to eliminate variables but both of my starters are inoperable at the moment heh

 

[Mogman]

Sounds like all you need is a GOOD switch and another starter

 

[jake20]

Sounds like all you need is a GOOD switch and another starter

Indeed, going to run the same tests I just did for any “new” switches that I get. Not sure about the starter procurement situation though, will make some calls tomorrow.

 

[mgFray]

Basically, the new switch I installed was still sending 13-16 volts to the solenoid positive wire even when in the off and run positions. The one I stole off my friend’s truck was sending 0 volts in the off and run position, as it should be like you stated.

So essentially with the new switch from Mac Motors, the truck would start fine, starter motor would disengage, but the bendix would remain partially engaged into the flexplate gear due to the 16V in the run position, thus the starter was being driven by the engine and bendix seized itself onto the shaft.

I’d try the remote start button too to eliminate variables but both of my starters are inoperable at the moment heh

If you got it from Mac, I'd definitely contact them about it. Maybe you just got unlucky and it really was a single bad switch. But if Mac Motor's inventory is full of bad switches, that is a much bigger problem (for them).

I'm trying to remember if my switch came from Mac or Kascar.. For some reason I think it was the later as Mac was out of stock at the time. (Earlier this summer.)

 

[jake20]

Yep that’s the plan, I still have a kascar switch coming in that’s been on backorder. Will be testing that one too as the previous ones they sent were the same type of shiny that Camo was talking about.

Either I’m really unlucky, or whoever is manufacturing these switches just can’t get it right. I tried looking on the electronic bay for some used original switches, but that seems like a futile effort.

 

[mgFray]

I just checked. I ordered my start switch from Mac Motors on 1/5/22.. Installed it on 4/22/22. So far no issues.

HUM 11614131
5930-00-134-5036

 

[jake20]

I just checked. I ordered my start switch from Mac Motors on 1/5/22.. Installed it on 4/22/22. So far no issues.

HUM 11614131
5930-00-134-5036

Hopefully it’s just a single one and not their entire inventory, will talk to em tomorrow.

In other news, spent a few hours and cleaned/wire wheeled/greased a bunch of grounds on the truck, along with installing the supplemental ground harness.

 

[Milcommoguy]

Hopefully it’s just a single one and not their entire inventory, will talk to em tomorrow.

In other news, spent a few hours and cleaned/wire wheeled/greased a bunch of grounds on the truck, along with installing the supplemental ground harness.

Not to say all the switches that are shinny are bad... But if one has seen some of the plating of imported parts, mainly electrical and gauges, One gets a feel for the questionable products. I too have been there 22 years ago with a speedometer. Got the call that it came in and picked it right up. 50 bucks later and an hour, it was installed. I and the M37 were happy for about 40 miles. How could this be. Shinny new and now busted. Investigation revealed, unusual bright finish of hardware & brackets, no manufactures name / identification, plastic not as durable. Needless to say... All parts are not created equal.

Wasn't the first time either. Was a flasher module, a gauge, overflow tank, and the speedo. Slow to learn I guess, LOL

Here a link to one of them. Do your own research for all the import parts... https://www.alibaba.com/product-det...645.html?spm=a2700.details.0.0.25b87f89DjBS9C

It sucks to have to pay twice to get it right, CAMO

 

[jake20]

Alright progress has been made. Mac Motors will be refunding me for the faulty switch and starter it burned up. In the meantime I’ve sourced a new starter and HPG is shipping me another start switch.

New starter has been installed, truck starts perfectly right now with an original switch from another truck. No bendix engagement when there isn’t supposed to be. Will report how the HPG switch does.

 

[gringeltaube]

No bendix engagement when there isn’t supposed to be.

... and while engaged, how deep does this one go into the flexplate?

I wouldn't be so happy with a contact pattern of only 1/2 of the width on the ring gear teeth - even if it starts (and sounds) perfectly normal, every time.

 

[Mogman]

... and while engaged, how deep does this one go into the flexplate?

I wouldn't be so happy with a contact pattern of only 1/2 of the width on the ring gear teeth - even if it starts (and sounds) perfectly normal, every time.

About 2/3 is actually normal it appears looking at a couple starters that I have, the bendix teeth are wider than the flex plate teeth

 

[jake20]

So after playing with 3 different starters, it’s definitely impossible for it to fully engage, at least on my truck. The collar on the armature doesn’t allow the bendix gear to travel the full width of the flexplate gear. I stuck my phone camera under there to take a look several times to make sure it was meshing good and not staying engaged after starting.

Overall it’s about 2/3 to 3/4 engaged when cranking. If you’re going off looks alone, closer to 5/6 but that last bit of the bendix gear doesn’t count because its beveled edges don’t actually contact the flexplate once engaged.

Some pics attached of the engagement while it’s cranking.