HHMWV Fuel tank leak

[roninsar]

New owner here! Just picked up my First HMMWV on Tuesday and during transport home (trailered about 350 miles), I noticed a leak on the tank. During a stop on the way home, I was walking around the truck while it was on the trailer, and I observed some fresh liquid on the front side of the rear-end A-arms. I then tracked the source back tot he bottom side of the fuel tank. After climbing underneath on the spot, we found the leak was coming from the top side of the tank, and appeared to be coming from a intake line into the tank.
Question could the line be loose, need replacing, or does the tank have an overflow feature etc. It seems to be a small issue, as the original owner who just purchased from IP back in the spring didn't mention this, and he has already replaced several things he found, that needed replacing. He was very knowledgeable and the kind of guy to replace things to have a sound vehicle. I have read on a previous thread on SS of prevented maintenance and/or a process to check and or prevent future issues with the fuel tank. any assistance would be greatly appreciated.
The vehicle in question is a 1987 HMMWV, 6.2 engine with 5100 original miles. Compared to others I have drove it rode like a Cadillac with the low miles that were on the truck.

By the way are there any HHMWV owners near the middle TN area that can chime in for future possible information.

Thanks Bruce

 

[Action]

Look in the right rear tire well at the bottom of the fill spout, for the rubber hose . Use long screwdriver and see if you can tighten the hose clamps. If that doesnt stop the leak, you may have to drop the tank.

 

[319cssb]

There is a seal on top of the tank that likes to go bad. Mine leaked when I filled the truck full during the hurricane.

 

[roninsar]

Action,
In dropping the tank, are you referring to replacing the tank and/or checking the top of the tank where the seal in located? I've studied some pics and have figured out it has seal located on top. If this is the case then would it be wise to go ahead and replace the tank while its on the ground or just replace the gasket?
On dropping the tank, what's the steps to keep the lines full etc so one doesn't have to bleed the lines down, or is this an issue on the Humvees?
Thanks for the replies!

 

[Action]

new newer tanks are cheap all over the web, but i dont know if they will fit ok in yours. There are just 2 straps holding the tank in. I do not know how to keep fuel in the lines. Gravity is not your friend. The top seal is easy to replace once the tank is out. Get as much fuel out before trying to drop the tank. Inside the tank is a "sock" on thd suction tibe. You may want to clean or replace that.

 

[jkcondrey]

Not sure if yours has this or not, but mine has a cutout inside the cab, beside rear passenger seat with four screws in it, about the size of a bible. Its directly over the access on the fuel tank. If you have this you can at least check those lines coming out and the seal.

 

[ikoinu]

Repeating what action has already said because this was my issue when I had a small puddle of diesel under the tank when filling:

There are 2 metal band clamps on the rubber hoses connecting the tank to the fill spout. The first one is on the inside of the wheel well, easy access. Flat head screwdriver will make sure that's tight.
Second one is more inside attaching the full tube to the tank, kind of hard to see. Get a long flat head screwdriver, 18"-24" range, use a flashlight to find the clamp, and tighten that one.
Solved my problem, and easier than dropping the tank to find the issue.

If that doesn't work, then look at the level gauge seal. If you are going through that trouble, might as well get a new style level gauge and full tank Gasket from Kascar, 2 birds with one stone type of thing.

 

[kdaniels]

ACTION...his truck is a 1987, they take the old style tanks which are few and far between these days. Those new ones on the web are for trucks that don't have the rotors up high on the drive line. I found a new one for my 87 about 15yrs ago at a guard unit in Montgomery and tried my best to talk them out of it, but it was a no go. Instead they gave me a used one that look new. If you intend to keep your truck a spare fuel tank wouldn't be a bad idea regardless of the year or model.

SEMPER FI !

keith

 

[darr3239]

Don't try to drop the tank until you have used a long screwdriver on the filler neck hose clamps.

I had to jam a piece of wood, between the tank and frame, in order to get enough room for the screwdriver. My problem was solved.

 

[Action]

ACTION...his truck is a 1987, they take the old style tanks which are few and far between these days. Those new ones on the web are for trucks that don't have the rotors up high on the drive line. I found a new one for my 87 about 15yrs ago at a guard unit in Montgomery and tried my best to talk them out of it, but it was a no go. Instead they gave me a used one that look new. If you intend to keep your truck a spare fuel tank wouldn't be a bad idea regardless of the year or model.

SEMPER FI !

keith

Yup. I don't know if he has the brake upgrade or not. That is why I said it may not fit his HMMWV. I don't know how the newer tanks fit with the 218, either.

 

[Cobra38]

I just fill mine 3/4 full. I should probably check into the clamps with the long screw driver tho.

 

[BLK HMMWV]

I still have my old style tank. (if anyone is looking for a used old style tank) I upgraded when I did the brake mod and power plant upgrade.
BH

 

[Zman1991]

There is a really good video on YouTube under the title Hummer Mods and Repairs for the M998 HMMWV. It will really give you a good look of how things are hooked up, removal, maintenance and repairs for the fuel tank. Hope this helps.

 

[roninsar]

Being new here, just what does it consist of on the brake mod?
ill check out the hoses and make sure their tight.
Thanks for all the feedback and assistance.

 

[Action]

Being new here, just what does it consist of on the brake mod?
ill check out the hoses and make sure their tight.
Thanks for all the feedback and assistance.

2new rear calipers with integrated e-brakes, and new cables. Then you get rid of the disc on the driveline. These brake kits used to be on epay often

 

[mturner2003]

This was the problem on mine as well. However, here's a little tip...

Don't bother with a flat head screwdriver. They are too hard to work with in long, tight spaces. Use a wobble extension or universal drive with a 5/16 or 8mm socket. Much better confirmation of contact and applied torque. Just don't go nuts.

 

[TOBASH]

There is a seal on top of the tank that likes to go bad. Mine leaked when I filled the truck full during the hurricane.

Exactly what happened to me. Repaired the seal and now it is dry there.

Of course, now I just sprung a leak at the hose leading into my new power steering pump.

It is always something!

Glad my leak waited till the temps dropped to the thirties, as I would have overheated working on the truck while the temps were in the 70's. :/

Long story short... The top tank gaskets go bad, and so does everything else eventually.

 

[Mogman]

If my 1992 has the E brakes on the rear calipers I can use a late style tank yes? what other changes are necessary to install a late style tank?
What year was that mod standard in production?

 

[Ajax MD]

Sorry to dredge this up.

I have a leak, might be the gasket might be the fill tube. It definitely happens when the tank is more full than less full. My truck is very old, has to be 80's because it has the old mirror mounts. I have the old parking brake (disc on drive shaft).

What's the latest on replacement fuel tanks for the older trucks? Can they be had? Do the new tanks fit if you retrofit with the parking brake upgrade?

Thanks.

 

[Mogman]

I am sure someone will confirm or deny but IIRC you do have to do a retrofit of the parking brake to fit the late style tank which is much easier to find than the original