LAXBUBBA
New member
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- MIDDLETOWN, DE
I'm a rookie. Only have very limited knowledge on diagnosing and repairing automotive issues. Good at researching.
Acquired a '87 M998 HUMMWV upgraded in '07 about three months ago. Has 6.5 L & 60 AMP alternator. Over that time, voltmeter seemed to be in the green maintaining charge. Always fired up immediately without turning over at all, when just tapping the toggle switch to START. Never any smoke.
While running through a major rain storm, water began dripping on my left foot. Then panel lights went out one at a time. The next day found leak and repaired it (Under the hood found a grommet with two wires going through it had pulled out of the deck that the wiper washer reservoir sits on) and replaced panel lights - The replacement lights worked. Also found a wire hanging down (unable to determine what the wire goes to) below light switch panel and the wires that connect to it, that had gotten wet from leak. Took connection apart of the wire that felt wet and then left apart after drying it out. Later in day I accidently started it not remembering to reconnect that wire. Uncharacteristically, It suddenly took about 10-15 turns to start. When it did fire up, a plume of white smoke came out of tail pipe.
Since then, it now typically turns over 4-5 times or more to fire up with some smoke, when before it would instantly fire up smokelessly before all this happened. If i'm not mistaken, the glow plug light now only briefly flashes on. Before it would stay one for about 10 seconds before starting it, especially for the first time during the day.
Several weeks later while coming back from a trip, I notice that the voltmeter was on the edge of the red/yellow level. Not sure if panel lights blowing, leaving wire apart, delayed starting and inability to keep batteries charged are all related with a common cause.
Have attached the response of a mechanic who attempted to evaluate and repair each problem.
"I have tested different components of the starting and charging system on the HUMVEE numerous times and the Alternator has been charging +/- 28V every time. I have noticed once that the full 28V were NOT reaching the batteries only had 24V that one time. The Voltage gauge on the dash has been in the green consistently. Started it up this morning and it was a delay start and smoke did come out of the tailpipe like customer described. After visiting all the links customer has sent, I think it would be best to start with replacing the ground cables, PCB box, and glow plugs. These seem to be the most common components to fail and since the Alternator has tested good each time I do not feel it is needed at this time. Customer has stated he would like to eventually upgrade the Alternator, so if he would like to upgrade at this time we can or if he decides to hold off I don't see it being an issue. I would prefer the customer to supply the parts since he has known good resources. "
Had planned on adding a number of components/accessories (fans, GPS, stereo, back up camera, ext & interior lighting) in the near future until this all happened. Don't want to add anything until I get the electrical charging system and starting issues resolved.
New PCBox, new plugs, put on a grounding harness from block to starter, alt, body and electronic starter (ESS) box ( same thing as PCBox isn't it ?) All three ?
Any other suggestions ? IE Higher output Alternator to handle new components/accessories I plan to add. Any other preventative measures or upgrades to bolster electrical system.
Best place to get replacement parts ?
Appreciate any and all feedback !
Acquired a '87 M998 HUMMWV upgraded in '07 about three months ago. Has 6.5 L & 60 AMP alternator. Over that time, voltmeter seemed to be in the green maintaining charge. Always fired up immediately without turning over at all, when just tapping the toggle switch to START. Never any smoke.
While running through a major rain storm, water began dripping on my left foot. Then panel lights went out one at a time. The next day found leak and repaired it (Under the hood found a grommet with two wires going through it had pulled out of the deck that the wiper washer reservoir sits on) and replaced panel lights - The replacement lights worked. Also found a wire hanging down (unable to determine what the wire goes to) below light switch panel and the wires that connect to it, that had gotten wet from leak. Took connection apart of the wire that felt wet and then left apart after drying it out. Later in day I accidently started it not remembering to reconnect that wire. Uncharacteristically, It suddenly took about 10-15 turns to start. When it did fire up, a plume of white smoke came out of tail pipe.
Since then, it now typically turns over 4-5 times or more to fire up with some smoke, when before it would instantly fire up smokelessly before all this happened. If i'm not mistaken, the glow plug light now only briefly flashes on. Before it would stay one for about 10 seconds before starting it, especially for the first time during the day.
Several weeks later while coming back from a trip, I notice that the voltmeter was on the edge of the red/yellow level. Not sure if panel lights blowing, leaving wire apart, delayed starting and inability to keep batteries charged are all related with a common cause.
Have attached the response of a mechanic who attempted to evaluate and repair each problem.
"I have tested different components of the starting and charging system on the HUMVEE numerous times and the Alternator has been charging +/- 28V every time. I have noticed once that the full 28V were NOT reaching the batteries only had 24V that one time. The Voltage gauge on the dash has been in the green consistently. Started it up this morning and it was a delay start and smoke did come out of the tailpipe like customer described. After visiting all the links customer has sent, I think it would be best to start with replacing the ground cables, PCB box, and glow plugs. These seem to be the most common components to fail and since the Alternator has tested good each time I do not feel it is needed at this time. Customer has stated he would like to eventually upgrade the Alternator, so if he would like to upgrade at this time we can or if he decides to hold off I don't see it being an issue. I would prefer the customer to supply the parts since he has known good resources. "
Had planned on adding a number of components/accessories (fans, GPS, stereo, back up camera, ext & interior lighting) in the near future until this all happened. Don't want to add anything until I get the electrical charging system and starting issues resolved.
New PCBox, new plugs, put on a grounding harness from block to starter, alt, body and electronic starter (ESS) box ( same thing as PCBox isn't it ?) All three ?
Any other suggestions ? IE Higher output Alternator to handle new components/accessories I plan to add. Any other preventative measures or upgrades to bolster electrical system.
Best place to get replacement parts ?
Appreciate any and all feedback !
especially since you do not have to factor in wet stacking... 
