Interchange – Page 5 – HMMWV Systems

December 2, 2018January 10, 2019

Stainless Screws: Substitute and Upgrade

The screws attaching the air cleaner shield 2540-01-196-4726 [2540011964726] (Fig 12, Item 34) to the body in conjunction with shield, expansion 5340-01-208-8688 [5340012088688] are listed as SCREW,TAPPING #10-16 X 1/2 5305-00-058-1082 [5305000581082].

This can easily be upgraded with a stainless screw (Search “#10 X 3/4″ Stainless Indented Hex Washer Head Screw”) on Amazon or your favorite auction site.

Note the four stainless screws holding the shield in place (at bottom of picture)

This same screw can be used as a substitute to mount the fuel tank filler neck, which specifically requires a 3/4″ length #10 5305-01-264-5874 [5305012645874] (Fig 199, Item 50).

NOTE: Although the call out for the expansion screw is for a 1/2″ length, there is adequate room to permit use of the 3/4″ length. Additionally, the requirement for 16 TPI isn’t relevant because it is essentially self-threading into nylon. The call out for the filler neck does require 12 TPI (because they thread into Tinnerman nuts), so purchase screws that meet this requirement and substitute for the 16 TPI thread. There is no reason to purchase different screws for each of these applications.

November 16, 2018December 11, 2018

Brake and Vent Line Fastening Bolts

Brake lines and vent lines are attached to the chassis through use of a 3/8-16 self threading bolt. The NSN associated with this is 5305-01-236-4349 [5305012364349]. The manufacturer part number for this is 172482.

This bolt is called out a number of times in the parts book, and in at least one place it is referred to as: SCREW, TAPPING 3/8-16 X .62. It is primarily used to hold down brake line and vent line loop clamps, and is even used on each hub to attach the vent line loop clamp to the hub.

There really isn’t an easy substitute that looks or works correctly on this. We found at least once on the 1038 where a mechanic (or other person) tried threading a 3/8-16 bolt into the frame to hold a cushion clamp on, but it simply would not tighten.

We have ordered these screws from some of the “big 3,” and they worked, although they seemed to be a bit longer than the call out. And after we acquired a bag of 100 of the proper screw (with the proper NSN), it was noted that the ones ordered from one of the “big 3” were slightly longer.

As these screws range from $0.16 to $0.25 per screw, we recommend using the correct screw as called out by the manufacturer. Because of its low price, the damage that could be caused by using an incorrect screw would far exceed the cost of using the correct fastener.

November 16, 2018December 4, 2018

Upgrade: Fuel Injector Return Lines

The 6.2 and 6.5 commonly will leak from the injector fuel return line hoses. (Fig. 11, Item 23). There is no NSN assigned to these hoses, rather they are cut to length from hose p/n 9439046. As these hoses age and dry out, they tend to crack and break, resulting in fuel leaks on the engine and onto the exhaust manifolds.

We installed new upgraded replacement hose sourced from Badger Diesel in Kenosha, Wisconsin. (262-859-2444). Unlike the original hose, the extremely small (and easily distorted) hose clamps 4730-00-150-6118 [4730001506118] are not required as the hose fastens securely to the fittings by itself..

Badger markets a complete kit to replace the return hoses as Badger Diesel 6265RLK. According to Badger, “This kit includes more than enough line to do the full job with 8″ of line per injector rather than the 3″ that the competition offers having only enough to barely do half the job. Thats 266% more line!” Badger further points out this hose is made in Germany, not China as is apparently their competitor’s hose.

In our opinion, this hose is a definite upgrade from the factory hose, and not having to use the extremely small and difficult-to-use hose clamps is a plus.

November 15, 2018January 6, 2019

Upgrade: Replace Transfer Case Cooling Line Hose Clamps with Fuel Injection Clamps

A common problem with standard hose clamps is that they will often tighten up unevenly, cock sideways, and require excessive torque to seal. Here, we have replaced the hose clamps on the transfer case cooling lines with fuel injection clamps (14-16mm range). While these generally cost considerably more than a standard hose clamp, they offer improved sealing and reliability. They can be bulk sourced at a number of online sites, often at a greatly reduced price.

The picture aboves shows where we replaced the original hose clamps 4730-01-118-8278 [4730011188278] with 14-16mm (9/16″-5/8″) fuel injection clamps. The original clamps were apparently installed at the factory from the top side of the frame prior to installing the body. We re-oriented the clamps so that they would be easier to adjust or remove & reinstall from under the vehicle.

These are still the original hoses that came with the powertrain. Although we had new hose to replace it with, we did remove and inspect the hoses. The hose itself remains “live” and showed no sign of cracking, so we retained the original hoses and installed the new clamps.

November 5, 2018January 6, 2019

Interchange: Fan Solenoid Mounting Clamp to SAE Size Hose Clamp

Both the fan control solenoid and mounting clamps had already been scavenged from the 1038.

Finding a replacement solenoid (Fig. 177, Item 5) 4810-01-192-5817 [4810011925817] was relatively simple, and just about every supplier stocks it.

It would be nice to find a cost-effective substitute, but as of yet, we have not located one that would be both cost-effective and a simple retrofit.

The clamps holding the solenoid to the body were also missing. The parts manual (Fig. 177, Item 6) does a call out for 4730-00-204-3491 [4730002043491] but fails to specify its size.

After researching the NSN and manufacturer number of C32P, we identified this clamp as a 40-64mm or (1 9/16″ to 2 1/2″) stainless gear clamp. This clamp is an SAE 32 hose clamp. We acquired a box of ten Breeze brand clamps for our application, although only one is required. In fact, it appeared during our research that Breeze or its parent company may have actually been suppliers of this clamp to the government as 4730-00-204-3491.

October 20, 2018December 19, 2018

Vent Tubing: Hub, Differential, Transmission and Transfer Case

Our project vehicle had been stripped of most of the vent lines, and some it appears may never have been correctly installed. (See: missing fitting and hose on front differential vent caused water infiltration).

Accordingly, we had to source and locate replacement or substitute hose and tubing for installation. All of the hoses and tubing are indicated in the parts manual as either P/N CPR104420-1 or P/N RB1450-1-4IDX1-20D.

Upon visual inspection, CPR104420-1 was identifiable as air brake tubing used on semi-trucks. One of the brand names for this is an Eaton product called Synflex®.

Synflex® used to vent rear differential and hubs and transfer along frame.

Upon further research, it was determined that CPR104420-1 is 1/4″ diameter tubing. (note this tubing is measured by O.D., not I.D.) Whereas CPR104420-2 is 3/8″ diameter. (CPR104420-2 is used as the main tube running parallel to the frame to vent the fuel tank).

We were able to identify RB1450-1-4IDX1-20D as being manufactured by Armstrong, and carries an NSN for bulk lengths as 4720-00-684-4033 [4720006844033]. This essentially is a durable 1/4″ I.D. hose, which has the appearance of 1/4″ fuel hose or similar.

There is a number of vendors that make a suitable replacement, although we noted the caveat of not using fuel line because it may not remain flexible enough over time for use on the front hubs. (they will constantly be flexing as the vehicle is steered).

It was suggested to us to consider use of silicone vacuum or vent hose. Silicone hose was simply not readily available at the time of manufacture and design of the HMMWV. Vendors cautioned against using silicone hose for oil or fuel carrying. The primary reason for not using silicone for fuel is that it simply isn’t rated for pressurized fuel. We determined that 1/4″ silicone hose would be appropriate for venting purposes, and noting its widespread use in commercial and agricultural applications gave us a level of comfort of its reliability.