Headlights keep burning out & will not cold start at all

Problem 1:

I've put 3 sets of headlights in my M998 and they always keep burning out. Anybody know whats happening? These suckers are expensive and want to get it fixed!

Problem 2:

Out of nowhere this thing will absolutely not cold start at all. The wait light comes on and shuts off like it always has and it will just keep cranking and blowing a lot of white smoke out of the exhaust.

Put in new glow plugs and temp sensor...didn't make a difference.

Anybody know what to start checking to get it fixed?

Thanks!

I can’t help you with the starting problem, but once you get it running put a volt meter on the batteries. It should read just under 28 volts. My guess is the voltage regulator may be over charging the system and that might be burning up the headlamps... It’s also hard on batteries.
Sorry I can’t help with the starting issue.

Have you confirmed that the glow plugs are actually lighting or have voltage going to them? I had a similar issue with cold starts being extremely hard to start. Unfortunately it ended up being the box not giving voltage to the glow plugs. While diagnosing I did find that advancing the timing helped a bit.

Check your grounds for the headlights. I have heard that bad grounds can cause headlights to burn out due to voltage issues.

Additional grounding, or a check of the grounding to the hood electrical connections is a good idea as stated, and I would add that you need to be careful with how you let the hood down. Many of us don't lower it slowly, but a good clunk of that hundred pound hood will jostle the filament in the incandescent headlights pretty hard. I burned/broke mine doing that when checking something right after running when the filaments and lamps were still hot.
I recommend LEDs as the solution. There are plenty of threads and links here with info, and prices keep coming down on aftermarket stuff. I used headlights intended for Jeeps, did have to cram them some but they work.

Bulldogger

For the headlights, like Bill said, check voltage. But I believe the correct voltage is at or slightly above 28v, not under 28v.

The grounding harness folks mentioned is easy to make:
https://gear-report.com/hmmwv-upgrades-make-diy-hmmwv-grounding-harness

For the starting issue, there is a lot of info in this article:
https://gear-report.com/help-hmmwv-wont-start-humvee-glow-plug-start-system-maintenance

Once you figure out why the headlights are burning out, I found a nice solution instead of buying expensive military headlights. look up Octane Lighting on amazon. They sell headlights that use a normal replaceable 24V halogen bulb, you need to buy two wiring harnesses cheap and go to Eriks military surplus for the shell connectors. Then all you need to replace is the halogen bulb 24V anywhere from $7 on up when they burn out. They work great in my Humvee, of course I dropped one while installing it lol and cracked it, but I bought 3 sets to put on other vehicles. [h=1]OCTANE LIGHTING 7" 24V Halogen Military Headlight Headlamp H4 Bulbs Crystal Clear 24 Volt Pair[/h][h=1]ZYHW 2 x H4 9003 Ceramic Wire Wiring Harness Sockets for Car Headlight[/h]