Fuel Tank Comparisons

Side-by-side of fuel tanks. (left) 2910-01-447-3911 [2910014473911] and
(right) 5582606

After receiving and unboxing our newly arrived 5582606 fuel tank, we decided to do a side-by-side comparison of them. As visible from the picture above, the later model tank is distinctly larger.

Visible on the rear of the tank is the cut-out allowed for the drive line parking brake.

Also of note is that the tank skidplate does not fit the older-style tank. Although we could have cut and used a brake to rebend it, we will store it for a future project. Additionally, it is clear that removal of the driveline would not be required to install or drop the older-style tank because of its reduced size.

Correct Fuel Tank

As explained in an earlier post, we unknowingly attempted to install a later model fuel tank into an early model HMMWV. And despite difficulty in locating the correct tank, we were able to. It arrived today, and we intend to install it in the next few days.

Boxed fuel tank 5582606 for early serial number HMMWVs with separate parking brake

As we install this tank, we will attempt to document and post any differences between this main fuel tank and the early tank.

Fuel Tank Woes

We had purchased a fuel tank for our M1038, as well as the missing straps, fuel level sender and other pertinent parts, and were ready for installation.

Top view of fuel tank ready to be installed

We were unaware, however, that the jumper between the fuel tank and the wiring harness was missing. So, using the correct Prestolite wire, wiring ends, and PET loom, we fabricated a replacement jumper. (Ensuring that it was made to military specifications).

UPDATE 3/ 24/2019: We fabricated the jumper at a 36″ length. As it turned out, the length could have easily also be made at 18″-24″ length. As it turned out, we cable-tied the excess to the fuel tank vent tube near the crossmember where the jumper connects to the harness. We suspect that should we have to remove the tank in the future, the extra length will prove “slack” to permit us to lower the tank without having to disconnect the jumper from the harness.

We were ready to install. Or so we thought. Even after removing the driveline, we found that we could not physically fit the tank into the area, as it hit the emergency brake caliper, rotor, and bracket.

We were simply unaware there was more than one main fuel tank. Our tank 2910-01-447-3911 [2910014473911] carries part number 12460105, and is easily located. As it turns out, we should have verified application through the UOC (Usable On Code) found in the parts TM in the far right side under description.

The UOC for a M998 is H13, whereas the UOC for a M1038 is H14. For practical purposes (other than differences between having a winch or not) either code would be accurate.

As it turned out, the NSN for the tank we had did not have the correct UOC, and we found the tank we required was part number 5582606, with no NSN provided for a part number. We simply had the wrong tank.

Through further research, we were able to identify a serial number split from 1 thru 44824, which uses the brake mounted against the rear differential on the driveshaft side. 2530-01-174-7441 [2530011747441].

We are well aware of operator complaints regarding this parking brake, but have found to often that operators attempt to adjust the brake from the brake handle adjustment (which is meant only to adjust for slack in the cable), and not properly adjust the brake from the caliper adjustment. We purposely chose to maintain this brake system because of our unit’s 4 digit serial number for historical purposes.

However, as noted above, we were completely unaware that maintaining this brake would require a fuel tank of limited availability.

Control Box & Controller

For our M1038, we obtained a mid-series control box, and a corresponding controller. The control box was in unused condition, and its connectors show indications that it has never been connected.

We located a controller that corresponds to the controller, but it had sustained some cosmetic damage.

Information on this controller 19207ASSY12446779 is scant. From what we can determine it was used on the M1113, and is similar to what was used on the M1114. (The M1113 used studs, as on this box, while the M1114 was threaded where the studs are).

It may also be referred to as a “silver label.” To make it clear, these are not EESS boxes. These boxes have been used on trucks up to the m115x, and are the generation between the old yellow/green label ones & the EESS. They are apparently a generation newer than the yellow label control boxes.

We have been cautioned that the operation of this box may make the “wait light” fail to light at higher ambient temperatures, but that is simply because it is not necessary to cycle the glow plugs.

Additionally, we have been cautioned that should a control box fail, there is a possibility that a vehicle fire may result. We will be installing a battery cut-off and will be testing the box before sending the vehicle out the door to reduce the potential for vehicle fire.

We have read good reviews on these boxes and that they are relatively reliable. However, if we note any issues we will reach out to an appropriate vendor for a newer generation control box and controller.

Rejuvenation of Battery Box

In preparation for installation of two new 6TL batteries to power the M1038, we removed the battery hold downs and tray to see the extent of acid damage on the aluminum.

Although there was extensive corrosion evident, the CARC seemed to provide a lot of protection from the acid. After spending considerable hours scraping, wire brushing and using a “scruffing” pad on a small air grinder, we applied several passes of baking soda and water to neutralize any remaining acid.

After thoroughly flushing and drying the surface, etching primer was applied and let dry. We debated about final coating and went with rubberized undercoating. This material is definitely acid resistant. And it appears that the box may have been originally coated with rubberized undercoating from the Marines.

We will next remove the shunt and mask off the entire battery box to be coated with the rubberized undercoating.

Heater Control Valve

The Heater Control Valve 4820-01-189-2107 [4820011892107] (AMG 12339966) was missing from our vehicle. We researched the different aftermarket valves available and were able to locate a replacement: Four Seasons P/N 74828.

This appears dimensionally identical to one in an M998:

Wiring: Silicone Lubricant / Waterproofing

Military Surplus Silicone Waterproofing

Anytime wiring with rubber boots are involved, it is always best to use a silicone lubricant. This assists in assembling the components, protects the rubber, and provides a further degree of waterproofing.

We have almost two cases of military surplus J941-C-5000 (also known as NRL S-75-G), which we acquired in the 1980’s. Since then, we have liberally used the silicone, and despite its age (Manufactured in 1954), it continues to be usable. Not bad for a 65 year old product!

We were unable to find further information of any kind on this product, however we have 30+ years using this material and have had superb results.

UPDATE: NRL S-75-G Interim was developed in World War II as a waterproofing lubricant to prevent machine gun failure caused by moisture freezing in solenoids at high altitudes (-20 F temperatures). (these failures are indicated as affecting the Cal .50 M3 and the 20 mm M24A1 Gun).

“The material is an open chain methyl silicone having a viscosity of 20 cSt at 77°F, and 300 cSt at -65°F, and a pour point of -75°F. Dodecane phosphoric acid (0.1 percent by weight) was added for lubrication. This material was labeled NRL S-75-G Interim.” Per: AMCP 706-26 at page 8-2 (Engineering Design Handbook, Guns Series, Automatic Weapons, Headquarters, U.S. Army Materiel Command, February 1970 [Document unclassified, but not marked as publicly released]).

Wiring: Circuit Breakers

As the breakers currently mounted in the HMMWV are around 30 years old (and have likely gone through countless fordings), we opted to replace them.

Newly installed 15 amp Klixon circuit breakers

These circuit breakers are “Klixon” style 15 amp breakers. The callout in the Parts Manual for these units are 5925-01-430-2318 [5925014302318]. However, this number seems to be obsolete. We were able to locate identical specification breakers under 5935-00-026-4767 [5935000264767]

These breakers have the same external dimensions and the same amp rating as the replaced breakers. The only difficult issue we had is that two of the connections would not release, and had to be replaced.

Interchange: Bow to Soft Top Rails

The screws attaching the bows to the side rails (Fig. 321, Item 6) calls out as 5305-00-059-3659 [5305000593659] with a general fastener number of MS51958-63 is essentially a 10-32 x 1/2″ pan head screw. Although we feel a standard 10-32 screw would be sufficient, we were able to source a number of the actual fasteners designated MS51958-63 at around the base price of the fastener from major vendors.

Although it is highly likely that a standard 10-32 screw would suffice in this application, we feel that use of the correct military fastener may give a slight performance advantage in both strength and corrosion resistance.

Of note, however, the fasteners we acquired indicate they are stainless, which is generally of a strength equivalent to a Grade 5 bolt. (of course, this depends on the type of stainless). We believe the vendor has mistaken plated fasteners as stainless. The packaging of the fasteners state they are MS51958-63. We have not reviewed the specifications of this fastener, but are of the opinion that even if stainless, they should suffice for holding the bows to the side rails.

Interchange: Soft Top Side Rail Screws (NAS1635-3LE12)

The screws at the front, middle, and rear of each rail are called out by different part numbers in the TM. The front screw (#1) 5305-01-210-6249 [5305012106249] with a manufacturer P/N of PL25D02P12 was not locatable.

The screw at the rear of the rail (#10) 5305-01-117-3396 [5305011173396] was similarly unlocatable, however we were able to locate this screw by its manufacturer P/N of NAS1635-3LE12. This is essentially a #10-32 x 3/4 screw. However, this has pre-applied locking compound. Additionally, we surmise this screw probably has a higher tensile strength than a standard 10-32 screw as it is an aircraft fastener.

As for the PL25D02P12 fastener called out for the front connection, at least one vendor (Kascar/real4wd.com) lists the NAS1635-3LE12 as an interchange. (at time of post, searching for the PL25D02P12 fastener comes up as NAS1635-3LE12) See: https://real4wd.com/store/catalog/search.aspx?keywords=PL25D02P12

In other words, we are comfortable that since both fasteners specifications are as a self-locking 10-32 x 3/4″, that use of the NAS1635-3LE12 is proper. There are apparently 50 in a box, and we have ordered 4 boxes to keep in stock.