Humvee Starter / Flexplate Teeth

[jake20]

Hey all,

I went to start my M1043A2 today, and the moment I was sort-of expecting finally came. A few weeks ago, the starter was engaged briefly while the engine was running, of course causing it to grind on the flexplate. After that, I started having rough starts where it feels that the starter isn't fully engaging into the teeth on the plate.

Today, I went to start the truck, and the starter kept stumbling and couldn't smoothly turn the engine over. I didn't attempt another start and decided to check on things.

I took off the cover over the starter to do some inspecting, here are my findings:

- The starter gear itself looks fine, all the teeth are intact and look pretty clean

- The flexplate gear is fine across a good amount of it, a few spots with minor chipped teeth, and one spot with decent chipping

- I looked at the wear patterns specifically, the flexplate indicates that the starter gear/bendix is only engaging on about half the width of the flexplate gear. The wear marks are easily visible in the attached photos

- For what it's worth, I recently re-soldered the cable that runs from the top of the engine wiring harness to the starter, thick gauge but not the thickest one going to the starter. My solder joint isn't something I'm necessarily proud of, it could be possible that this has an impact on the amount of current the bendix is getting to properly engage. I will be re-doing this soon

- Batteries are new and very strong



So with my findings, I have some questions (I would like to re-iterate that this is what I think, I am not a professional lol):

- Is there a way to adjust how far the bendix extends onto the flexplate's gear? By my rough estimates, it's only engaging half the width of the gears, and if some of the teeth are chipped, it might be trying to engage on even less than that, and stumbling because the bendix gear has beveled edges

- I know that a new flexplate would be a good idea, but I've also seen ones in worse condition in the past, would mine still be considered passable? The pics attached show the worst of the chewed up teeth, the rest are pretty good

- I know that shims exist for the starter, but based on my research, they're only to adjust the distance between the gears, not the bendix engagement travel?

- Any specific tips on checking for a weak bendix?


I'm all for documentation for the future, more than happy to provide more details.

Thanks all!

 

[Mogman]

Does your starter have a shim? It MIGHT be possible the gear backlash is so tight the gear cannot/does not fully engage

 

[jake20]

It does in fact have a shim if I’m correct. The little triangle piece sticking out in this photo.

So the bendix should fully engage across the entire width of the flexplate, right?

 

[Mogman]

Yes it has a shim, well I would assume the folks that engineered it wanted to use the entire width of the flex plate. but I have never been able to observe it myself.
The flex plate could also be bent, it happens. You may want to measure it against some reference point in several different rotational positions

 

[Mogman]

My next move would be to replace the starter and carefully file the damaged teeth so there is no interference from the existing damage, it really does not look bad enough to condemn the flex plate quite yet unless it is bent.
Also where does that wire you repaired go? it has an asphalt loom so it is not part of the basic harness, maybe to the 28V terminal on the alt? if so doubtful that is part of the issue as long as it is charging OK

 

[Mogman]

BTW that damaged area was from the starter trying to engage the flex plate when the engine was not running, when you accidentally engage the starter while the engine is running you tend to round off the gear edges all the way around the flex plate.
You might put a voltmeter on the starter ground lug and the starter lug, the one that is on the bottom of the starter and see how much voltage is there when trying to crank it.

 

[jake20]

So I did consider the flexplate possibly being bent. I rotated the crankshaft over one revolution by hand, and I saw no variances in its position.

That cable I repaired goes to the starter itself, but I don’t know where it originates from yet. What I do know is that when testing it, it has constant power, regardless of the ignition position. I learned this by accidentally doing some surprise welding.

Was getting a bolt off in the area in preparation for fixing it and I made some angry pixie sparks fly after touching it with a wrench. I suppose it’s also within the realm of possibility that this could have damaged the starter?

In any case, these starting issues only started happening after the first time the starter was accidentally engaged while the engine was running. Which, to your point about how it should damage the teeth in that scenario, leaves me a little puzzled haha

Thank you for the info thus far, will see what I can find out tomorrow. Are used take-out starters a good idea or is completely new worth it?

 

[Mogman]

So that would be the 200A charging cable, probably not an issue.
You may want to check all the cable connections between the battery and the starter.
There are only two mechanical components, the flex plate and the starter, as long as there is no issue with juice getting to the starter it narrows the possibilities down quite a bit.
Cannot advise on the pull out vs new/rebuilt, depends on how much you trust the source, Do you have a good local starter shop? most of the older/larger shops speak 24V no problem, might want to have them look and see if there is an obvious issue with the one you have.

 

[osteo16]

mY 2Cents, Id try to reman that starter before spending 6-700 bucks on a newer one.. Could be some minimal damage from engaging starter with motor running... Might just need a little lube on bendix.. But i know nothing Coulda popped a few metal shards in there..bad bushing, a little rust ??

 

[Mogman]

"In any case, these starting issues only started happening after the first time the starter was accidentally engaged while the engine was running. Which, to your point about how it should damage the teeth in that scenario, leaves me a little puzzled haha"

It could be that the starter gear would not engage when it was accidentally activated when running, damaging/bending the Bendix or the fork that moves the Bendix into place, like osteo16 said I would run it to a shop and have them do a look-see

 

[jake20]

Luckily I’ve got another truck I can compare it to, will take the cover off that one tomorrow and see if I notice any vast differences. At least I’m armed with enough information to do more investigation now heh

@osteo16 I’m on the edge about taking it apart myself, depends on how I’m feeling after removing it Will also have to see if rebuild kits are a thing for these? My truck is somehow 95% rust free, everything was coated in some sort of black rubbery sealant. Makes it a pain to remove bolts slathered in it but overall it’s very clean. It’s never seen any salt, which it will this winter sadly.

I’ve seen tidbits of info regarding new vs old style starters and/or brackets of sorts. Is that anything to look out for if I did end up having to get another?

 

[TOBASH]

This might be an issue with the solenoid. Also these are sealed units to allow for driving and starting while submerged.


Dust builds up and might interfere with Bendix function as dust cannot escape over time. Opening the starter and cleaning it out might help.

 

[osteo16]

INSTALL the new style hanger bracket,,, Its J shaped to hold one end on the starter,, Yours may already have it. That thing is a Biotch to install if you have to hold it all by itself up and put in bolts,, Im 6'2 and 240..... Im still sweating with tricep pain 2 years later,, And from what ive seen there are "rebuild kits" available,, But good point on Mogman about possibly bent bendix (shaft) but these are pretty hardy starters,, I usually tear things apart, if its obviuos I fix it, If not, i replace it,, That runon sentance is atrocious,

 

[jake20]

Sounds like I'll be attempting to yank the starter out today, will take it apart and see what I can find. That video regarding the bendix was pretty informative, will compare what I'm seeing on mine as well.

 

[jake20]

Got it out with the help of a jack stand, I now know what everyone means by the J style bracket, that made it pretty decent to do.

Contemplating whether I should start taking the bendix facing side apart to check for obvious issues or just have a shop deal with it.

All the teeth look fine at least.

 

[mgFray]

Don't mean to threadjack, but does anyone have a pointer to the new style J bracket? NSN or other identifier so I can order one? Bendix on my starter is _slowly_ going, sometimes it won't engage. I've got a new starter in a box when the time comes, but I'm going to wait as long as I can. But I'd like to throw the bracket in the box with the starter and swap them both at the same time.

 

[Mogman]

Kick the solendoid on the small terminal and see if the bendix goes all the way out

 

[jake20]

Don't mean to threadjack, but does anyone have a pointer to the new style J bracket? NSN or other identifier so I can order one? Bendix on my starter is _slowly_ going, sometimes it won't engage. I've got a new starter in a box when the time comes, but I'm going to wait as long as I can. But I'd like to throw the bracket in the box with the starter and swap them both at the same time.

So I’ve never heard of this site but this is the bracket you want: https://hummerh1parts.com/12469281.html

Could try to cross-google the part numbers. Could also call Kascar in the morning and check with Ron or Mike

 

[mgFray]

So I’ve never heard of this site but this is the bracket you want: https://hummerh1parts.com/12469281.html

Could try to cross-google the part numbers. Could also call Kascar in the morning and check with Ron or Mike

Thank you! Found it at MacMotors.

NSN: 5340-01-457-5734 / 5340014575734
12469281 (HUM)
SUPPORT STARTER MOTOR

Basically the same price as the place you found, but I've ordered from Mac before.

 

[jake20]

Kick the solendoid on the small terminal and see if the bendix goes all the way out

Alright I tried it both electrically and manually through the big access hole on the side of the solenoid.

It seems to kick out very strong and fine, I did notice that the shaft itself and the collar on it seems to move too, not sure if it’s normal.

Video of electric check:

Video of manual check: