1986 M998 Starter Issues

[Crig]

Hello y’all, I just got my first humvee about 3 weeks ago so I’m quite new to all of this.
Last week I installed a keyed ignition not knowing they’re notorious for butchering the starter and unfortunately for me, it did exactly that.
With the keyed ignition installed, the starter wouldn’t disengage from the flywheel until I put it in drive or reverse and that was the first issue I had with it. I then read online that the keyed ignition is junk so I removed it and put the original ignition switch in. My current issue now is that the truck doesn’t start as it normally should. When I flip the switch to the run position, I hear no clunk and the glow plug wait light doesn’t turn on and when it’s flipped to the start position the glow plug wait light pops on for half a second and the truck starts up immediately with the starter and flywheel grinding together still. When I release the switch, the truck shuts off. So basically It only runs if I hold the switch in the start position and the starter and flywheel grind against each other.
When I crawled underneath to remove the starter to take assess any potential damages, I discovered that I have only 1 bolt holding it into place and am missing the other bolt and the nut that secures it to the bracket. I spoke to someone who believes that is the reason why my starter and flywheel is grinding together and while that seems plausible, everything was working fine for almost a month until I put that forsaken keyed ignition in.
Any insight or advice on what I should do about this is greatly appreciated. I fear that it may be more than just the starter solenoid that got jacked up and I’m looking into getting the starter looked at and possibly repaired.

 

[TOBASH]

1) read the TM’s (technical manuals) that are provided for free above

2) update/upgrade to the new starter bracket. The starters are heavy and the new style bracket makes life easier.

3) extract the old broken starter bolt and use 2 brand new starter bolts.

Kascar and Hummer Parts Guy and 86humV and several other vendors here should have all the parts you need.

Welcome and best of luck

 

[Mogman]

WELCOME to the SS forums!!!
It sounds like among other things you have the run switch wired incorrectly.

 

[Mogman]

After checking the wiring on the run switch make sure you have that missing bolt in place before ever trying to start it again, it matters not that it was working that way before, there will be a time that disaster will strike and it could be the next time you hit start.
If that starter drops out of place it will short the battery cables to the chassis and all kinds of mean and nasty stuff will ensue

 

[TOBASH]

Disconnect the batteries prior to fixing the starter and its switch, or you will blow the glow plug controller and you’ll be calling me about a “Genius Box”.

Before doing any and all electrical work on your truck you MUST MUST MUST disconnect the batteries, or else you’ll blow the PCB/EESS also known as the glow plug controller.

A 500-1000 amp cutoff switch makes cutting power easier and also acts as a kill switch.

 

[Milcommoguy]

Or you can call me about the Camotek Controller.

The one and only. Not a copy, CAMO

 

[Crig]

Or you can call me about the Camotek Controller.

The one and only. Not a copy, CAMO

what is that?

 

[Crig]

Disconnect the batteries prior to fixing the starter and its switch, or you will blow the glow plug controller and you’ll be calling me about a “Genius Box”.

Before doing any and all electrical work on your truck you MUST MUST MUST disconnect the batteries, or else you’ll blow the PCB/EESS also known as the glow plug controller.

A 500-1000 amp cutoff switch makes cutting power easier and also acts as a kill switch.

I always disconnect batteries in my vehicles when I’m playing with electrical systems cause that stuff scares me a little lol. Probably a stupid question but since there’s 2 batteries, is it sufficient to disconnect the rear most battery and leave the other alone?

 

[Mogman]

If you do not have any 12V devices connected to the batteries then any one of the 4 connections will leave it inert.
If you do then remove the 12V connections while you troubleshoot this problem, you should also unplug the TSU on the passenger side of the water cross over to help keep you from frying your glow plugs.

 

[TOBASH]

I always disconnect batteries in my vehicles when I’m playing with electrical systems cause that stuff scares me a little lol. Probably a stupid question but since there’s 2 batteries, is it sufficient to disconnect the rear most battery and leave the other alone?

Once you interrupt the energy flow in a set of batteries connected in series, you have essentially disconnected the circuit.

Just disconnecting the connection between the two batteries, if done carefully and correctly, will remove power from the circuit.

When you play with electrics on a HMMWV with a regular glow plug EESS/PCB and you do so without disconnecting the batteries, you will blow out the integrated circuits in the glow plug controller. Hence my comments about needing a “Genius Box” If you do this wrong.

How to bypass PCB? I am aware some HMMWV owners have done it. TOBASH

I'm not trying to speak sacrilege here, and I don't want to precipitate a war of words. :shock: How might I build a manual control box? My 24Volt Landcruiser just uses a glow wire to show glow plugs are ready, and then she just starts right up with the twist of a key. Civilian 6.2 Diesel...

www.steelsoldiers.com

 

[mgFray]

My HMMWV has a sticker that says (when the 12V system is connected) that you should disconnect the 24V GND and THEN disconnect the middle "ground". (Basically both wires on the - (negative) terminals.). This will prevent any backfeed of power on the 12V circuit (if yours has that.)

Note, 12V circuit isn't common on an original 1986 model, but might be if it's been rebuilt or upgraded.