In an earlier post, we discussed interchange for the quick connector used on the fan clutch. Pictured below is the commercial equivalent of 4730-00-900-3296 [4730009003296] (Figure 178, Item 23), which is simply a 1/8″ x 1/8″ NPT nipple.
Although there are varying opinions on pipe dopes v. teflon tape, we prefer to use Rectorseal #5. It does come second only to anti-sieze at managing to make a mess, but we have successfully used this material for decades without encountering leaks.
Pictured below is the nipple and the quick disconnect discussed in the earlier posting. This is essentially one half of what is shown as Item 7 in Figure 178, and has been assembled to the fan clutch.
Below is the quick disconnect connected together along with hose 4720-01-189-0853 [4720011890853]. Note we have applied Rectorseal to all pipe threads.
The fan used for either 6.2 or the 6.5 NA on the v-belt application is4140-01-211-8403 [4140012118403]. As discussed in this post, the quality and materials appear to be comparable to OEM. The fan itself centers on the diameter of the fan clutch. We had to dress the inside of the fan in order to install it. We do not feel this to be a flaw, but rather precise hand-fitting of the fan to the fan clutch.
The lock washers taken off of the fan appeared to have not retained its spring-like characteristics. We believe they used Grade 5 or less washers on installation. We replaced those washers with Grade 8 (the gold ones) to ensure locking capacity. (Of note, we also used Blue Loctite as an extra safety measure).
The silver lock washers were removed from the vehicle, the gold Grade 8 ones were used to replace them. Note: there are four lock washers required, only two of each were photographed as examples.Picture of fan assembled to fan clutch.
Having disassembled, inspected and repaired the fan clutch in a prior post, we install the clutch to the water pump (of which we discussed interchanges).
Torquing fan clutch to water pump bolts. Note use of aluminum tubing to stop rotation of fan assembly during torquing.
We were unable to easily locate the torque specifications for the fasteners. We referred to Alma Bolt Company & Prime Fasteners’ torque specifications for Grade 5 and Grade 8 bolts. Being that the fasteners on our powerplant were socket head (allen bolt), this is generally an indication of a Grade 8 fastener. According to Alma Bolt’s chart, a 3/8″ Grade 8 has a specified torque of 44 ft. lbs. for a plain bolt, and 33 ft. lbs. for a plated (or wet) bolt.
We set our torque wrench to 32 ft. lbs. and after applying Red Loctite to each fastener, evenly tightened down the fan clutch. After subsequent review, we note that TM 9-2320-280-20-2 specifies 45 lb-ft (page 3-135 Change 3 at c.1.). This is within the specifications provided in the Alma Bolt chart, as the TM does not specify use of loctite which lubricates the thread causing a lower torque reading to equal the same “tightness” as a higher torque with dry threads.
The first step (once the fan clutch has been removed from the engine) is to remove the lock nut 5310-01-194-0481 [5310011940481] and locking tab 5310-01-189-8468 [5310011898468] from the face of the cylinder assembly 2930-01-189-1744 [2930011891744].
Self locking nut and locking tab from front of fan clutch
Next, install two 3/8 x 5″ (or so) bolts as shown below and tighten the shaft assembly 4079-38441-01 (no NSN) into housing assembly 4040-38442-01 (no NSN) enough to release the spring tension to remove the six capscrews 5305-00-052-6456 [5305000526456] holding the back plate on . Remove the backing plate. Do not, under any circumstance, remove the backing plate screws without a method (such as the bolts indicated in the picture) in place. There is a spring under pressure and failure to properly restrain it can lead to serious injury or even death.
Once the backing plate is removed, the clutch lining 2930-01-189-8643 [2930011898643] can be removed. It is not uncommon to stop at this phase, if the problem was that the fan wouldn’t DIS-engage because the lining had “frozen” to the shaft assembly. If not being replaced, the lining can be cleaned up using emery cloth or similar. The clutch surface of the shaft assembly can also be polished in this manner.
Friction lining removed, shaft assembly under spring tension (held safely by 3/8 bolts).
Once the spring pressure is completely relieved by slowly releasing tension on the safety bolts, the safety bolts can be removed. Inspect the inner bearings as well as the Torrington-style bearing and seals. Replace any damaged parts.
The below view shows the spring, seal and inner bearing. Ensure all O-rings are serviceable, and that the bearing surface on the shaft assembly is not damaged.
On reassembly, there is often leakage at the front O-ring, even when a new O-ring is used. Because of the likelihood of leakage, we recommend use of Loctite® 518 (or similar) on the sealing surface indicated by the Red Arrow in the picture below, as well as the corresponding location.
Reassemble the entire unit as it was disassembled. Again, Use safety precautions during reassembly because you are putting a lot of potential energy into the spring as it is tightened. Improper assembly can potentially cause serious injury or even death. If you have any doubts, please refer this to a professional or person experienced in assembling spring loaded machinery.
Left side, hose 4720-01-196-1636 designed for early version; Right side, hose 4720-01-360-2380
As our M1038 was an extremely early version, we assumed it would use the hose for the earlier version 4720-01-196-1636 [4720011961636] (Fig. 27, Item 7). However, we apparently had a later version tank 2930-01-256-5350 [2930012565350], so we required hose 4720-01-360-2380 [4720013602380] (Fig. 27, Item 9).
We note that we installed the hose intended for the earlier tank and could have simply cut off the excess length. However, there is a slightly different bend that gave us some concern about clearance with the radiator side shield. (After we installed the side shield, however, it was clear that cutting the earlier version hose would clear)
We were unable to locate specifically where the vent line from the rear routes around the right motor mount. We crawled under one of the M998s on the ranch and were able to snake a cell phone up to take some pictures.
Lower Red Arrow – Vent line from rear of vehicle; Upper Red Arrow – Fuel Tank Vent line to filter/intake stack; Lower Green Arrow – Fuel line from tank; Upper Green Arrow – Return line to tank.
As best as we can tell, there is simply no cushion clamp to mount the vent line, and it lays across the frame between the motor mount and the body mount (just under the mount flange riveted to the body).
Lower Red Arrow – rear vent line; Upper Red Arrow – fuel tank vent line
Viewed from the rear of the RH front body mount, it is clear that the rear vent line leaves the top of the frame to lay across the frame support for the body mount. Also visible is the fuel tank vent arcing upward underneath the fuel line support and cushion clamps.
The bay lights unintentionally caused this picture to have a “filter” effect, which was not desired. Most of the work from the last update picture has been connections and hookups on the engine and powertrain.
Externally, the air filtration system and fording intake stack have been installed. Additionally, all of the axle, transmission, and transfer case vents have been connected, as well as the fording valve, CDR and power steering. The only plumbing left to install is the fuel and transmission cooling lines.
We believe we are still on target for a February painting schedule.
As in previous posts, we have identified hose clamp sizes and their commercial interchange numbers. For the heater hoses, we have confirmed that SAE 10 is the correct size. Above are Breeze brand clamps, and Breeze has a history of manufacturing hose clamps for military use.
SAE Size 10 hose clamps installed on manifold to heater hose pipe.
The above figure appears as if it is a straightforward task to insert the cup sensor to CDR vent hose (No. 1 in picture).
In fact, even the instructions, Sec. 12-13 (TM 9-2320-280-3) makes it appear that you simply have to “route vent line through “A” beam.”
It truly is not a simple task. Ours being a Marine unit seems to be lacking in most of the insulation. It did, however, have the insulation installed inside the “A” beam. We erroneously made the assumption that since our HMMWV was originally equipped with the fording system, it should be as simple as the manual indicated. We spent several hours trying to thread the hose from both the top and the bottom with no success. The hose would consistently stop around the halfway point.
After running the lift up and down a number of times, we decided to see whether we could “fish” a piece of 3/8″ air brake tubing through the pillar. Although it took considerable effort, we were able to push the brake tubing completely through. We then connected the tubing to the hose with a 1/4″ hose barb and attempted pulling the hose through. That method failed on several tries.
We were ultimately successful using pure silicone (silicone gel for waterproofing / rubber boots, etc., not RTV) to lube the end of the hose and about half way up. The hose easily slid through. We suspect that there was just too much friction where the hose was somewhat pressed against the insulation.
Being that we have a crate of circa 1960 Dow Corning military surplus silicone, there was no cost. However, in the event you aren’t oversupplied with silicone gel, we strongly suspect that tire bead lubricant or even dishwashing soap would also serve as well.
View of CDR to Sensor Cup vent line as it enters top of RH “A” beamView of CDR to Sensor Cup vent line connected to CDR. Note routing of vent line across top of transmission dip stick tube. (this tube will be replaced with a DWF tube)
Arrows indicating locations of three hose clamps 4730-01-189-0871
Based on the call-out from the parts manual, the three hose clamps indicated below are 4730-01-189-0871 [4730011890871] or manufacturer number H68SS. Upon our research, these part numbers cross over to an SAE 68 hose clamp. Unfortunately, while size 68 clamps can be located, they are not generally commercially available. The standard (and readily available) sizes are either SAE 64 or SAE 72. We ordered both.
As it turned out (and we will post a picture later), SAE 64 is the perfect size for these three locations. We have noted that the specifications almost always call out a hose clamp considerably longer than necessary, and often leaving too much of a “tail” to grab debris, bend, and cut hands. (See photo below).
M998 Air Cleaner hose clamp showing excessive “tail” when called out part used
This hose clamp was unmodified and as received from the military. Based on what we could tell, this was a SAE 68 hose clamp.
We ordered the SAE 72 hose clamps to interchange for the clamps called out 4730-00-359-9487 [4730003599487] for use on the fording elbow 4720-01-194-5338 [4720011945338]. Although we have not yet installed these clamps, we predict they will have a considerable tail. However, those hose clamps are (for the most part) not quite as visible. On visual inspection, it appears that the SAE 68 (and possibly SAE 64) clamps may also be appropriate at that location. We will update should this information be found incorrect.
