[Lots of] Water in M1008 Fuel Tank

[MaximumBob]

1985 M1008 was a communication truck I think - had the canvas on the back (which probably makes it an M1028? At any rate, I've had the truck for about 1 year and have never had it running. Just now getting back on the project.

When I first purchased it from GL here in FL, I pumped out the tank - removed the rubber filler hose from the top of the tank by removing the rear drivers' side wheel and working through the wheel well. Once most of the fuel was pumped out (Harbor Freight #3878 $6.99 on sale) I lowered the rear drivers' side until the brake drum was sitting on the ground - this brought all the remaining fuel down to the back of the tank near the filler spout. During this effort (again about 1 year ago) I pulled about 1/2 gallon of water off the very bottom of the tank. Knowing that I wasn't going to get to the project for a while I refilled the tank fully - with fresh diesel and some Stabil (sp?) because I didn't want the rapid changes in temperature and humidity here in Florida to cause more water to condense inside the tank.

Enter Florida hurricane season - after one particularly nasty storm last year I went over to the shop (where I store the M100 to find a 20' diameter spot of dead grass - radiating out from around the [then recently filled] fuel tank. (Sort of a diesel Silkwood). At that time I pumped about 5 gallons of fuel off the top of the tank assuming that there was some sort of water leak into the tank.

Today we finally got around to repeating the full (rear-wheel-brake-drum-on-the-ground) tank pump down and we pulled at least 5 gallons of water out of the tank - probably more like 10 gallons.

I don't think that this was an act of vandalism - I genuinely think that rain water is getting in somehow. Both the filler hose and breather hose were firmly in place and appear to be sealed.

Any suggestions? Is it possible that one of the holes that is directly above the tank is dripping water somewhere where it could find its way into the tank? Naturally, I will work to seal the bolt holes in the bed, but if there is a larger problem, now is the time to go after it with the tank completely empty.

Related, how difficult is it to remove the tank - I have not looked up in the manual yet, but assume that I've got the fuel pickup, return and sending unit to remove. Are these under the cab or under the bed?

Again, any suggestions would be greatly appreciated.

Thanks,

MaximumBob (feeling more like MinimumBob at the moment!)

 

[Crash_AF]

I would recommend pulling the entire bed to work on the fuel tank. I've always found that to be MUCH easier than trying to do it from under the truck.

I don't know where water could be getting in unless the military accidentally drilled a hole in the tank while installing gear in the bed.

Later,
Joe

 

[CCATLETT1984]

I would drop the tank for sure, sounds like the sending unit isnt sealing on the top of the tank.

its quite easy, esp. since you have the tank empty already. Undo the bolts holdin on the skidplate, then you undo the two nuts on the inside of the frame that the tank straps are connected to, then undo the bolts that hold the tank mounts to the frame.

 

[papercu]

M1008

Acording to the -10 (available on this site along with the -20 and -24P) says this about the M1028:
"The M1028 is equipped to accept a 100 amp/28 v electrical system and S250 communications shelter and a communication kit."
Just by that I would think, if yours has canvas it would be a M1008. It should /will be on the data plate. Wayne

 

[CUCVFAN]

RE: M1008

M1008 & M1008A1 would have rear covers. 5th digit of VIN="G", then it's a M1008 or M1008A1. M1031, M1010 & M1028 variants are "H".

With that much crap in the tank, I think I would spend the money for a new one and just replace it. Shop around on eBay and you can get an aftermarket one shipped for about $90. No sense trying to clean it out if it's had water in it for a year. Just my ...

 

[AJMBLAZER]

RE: M1008

I forget, did we ever decide if the plastic tanks were still available? That would eliminate the rusting problem entirely.

 

[cjtroutt]

sounds like the rubber o ring that seals the sending unit could be dryed out or flat out gone
take look at that Than happend to me on V1991 5/4 UV5 same Tank street side.

 

[jimm1009]

Also fuel contamination. Kerosene and JP-8 (Actually all jet fuels) hold water for a while but if you let it sit undisturbed for 24 hours it will settle out and you can sump it out the bottom.
If it came from Uncle Sam like that or if it came from your last load or two of fuel that happens.
On the M1009 there is a suction line that is capped off that goes clear to the bottom of the tank. You can apply suction here at this tube you can suck out the water that has settled to the bottom.
I don't have a M1008 or other 5/4 pickup verison of the CUCV but it stands to reason that they should all have this tube.
Any M1008 owners know about this feature or if those other CUCV series trucks have it too?
jimm1009

 

[MrJJ]

All cucv's have that drain pipe.
I own a 84 M1008 and have just yesterday released my tank from the truck .
He had stand still for 2 years the engine started ok , but now runs bad at idel and will not excellerate top speed 35Mph.
Wanted to drain/clean the tank.
It was a good idee tank was full of flakes , and the tankfilter was fall apart .
There is a valve in it with a screw on filter this was lose and the filter was full of diesel flakes.