HMMWV INFO

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If you Have any newer or more complete Schematics email me so I can update this page.

 

WARNING on HMMWV's Spindles Coming Off.

I was driving my 1992 M1042 (it has 4,800 miles on it) down the road at 58mph when, without any warning my truck suddenly swerved violently from side to side. I managed to get it stopped and over to the shoulder of the road. I got out and looked around the truck, and my rear passenger side wheel was setting about 15 degrees out of plumb, but all of the lug nuts were on and apparently tight. I looked under the truck, and I could see the outer wheel bearing, and hub oil was everywhere. When the tow truck came and lifted the rear of the truck, the wheel fell completely off, with the spindle still attached.

I got the truck back into my shop and and surveyed the damage. The outer geared hub seal was damaged, and the spindle was scored on the inner bearing race. The threads on the spindle were fine.

I found a link to AM General's web site and discovered the problem. The spindle nut retaining washer was defective and allowed the nut to back off, causing the wheel to completely separate from the geared hub.Read the Doc

All HUMMER Civilian (H1) vehicles use and entirely different method of securing the wheel spindle.

PS: Add the "spindle locking tab" problem to the list of why ex-mil. HMMWV's were never intended to get in the hands of the general public.

Read about Spindles

Tachometer

The mil Tach I have is made by Motorola for the government and goes up to 3000. If I am pushing it a little on the highway it will go a little further maybe up to 3200 or 3300 if the numbers were printed that high, but AMG and the Army do not feel that the truck needs to be turning more RPMS than that. The engine is governed at its red line of 3600 with the DB2 injection pump but DDA states that 3000 was the max sustained RPM under load. Really even that high is a little hard on it but if you are on the highway I usually go 60-65 cruising with the 3L80 trans. Slower then that on today's roads is a pain. I know it would be happier at 55 but its just too slow.

The DDA 6.2L that was put into the HMMWV's was spec 'ed at 3900 to 4100 RPM's"High Idle" (basically meaning; transmission in neutral and mashing the pedal to the floor until the test tach reads between 3,900 & 4,100 without the engine going ballistic).

Calibration: With the speeds given and no locking torque converter, use just enough throttle to maintain speed on level ground. You will be very close to the exact tach setting. Just adjust tach while at 45 MPH and check the other speeds and the idle RPM. For an exact method you can find a mechanic who has a test tach and set it up at 1000 RPM.



The solution for Humvee and early Hummers without tach's and drives for them is to use a Tiny Tach. it's simple to install, the transducer clamps on any injector line. Connect the power and ground wires and away you go. It will even work off a 9v battery if wiring isn't your thing. The Humvee has 1/4 " lines when ordering the transducer and I'd suspect early Hummers are the same.

Hmmwv 24 to 12 volt Converter


I use a powerstream super power 800 24v/13.8v DC_DC converter. It's a very simple unit to install and has it's own cooling fan. I have had very good luck in my HMMWV. I draw up to 80 amps constantly.

To get 12v reliably without wrecking batteries in a Humvee I use a REDARC charge equalizer. It has been fitted for two years now with zero problems. I run 12v HF radio, refrigerator, CB, stereo, air compressor, nicad battery charger, etc etc. the website is www.redarc.com.au look for charge equalizers.

 

Rear Pan Oil Seal (unofficial)


From 84 to 87 the oil pan sealed directly without the rear seal. From what I understand the pans leaked all the time. From 88 till the present the rear seal was used. The early pan has a 2 1/2" drop in the back where the new pan has a 2 7/8" drop where you need to use the rear seal. The time from 84-87 is unofficial. It came from an old hmmwv mechanic.

Additional Comments: The 84- 87 oil pans did have a rear gasket, it was a multi piece gasket set just like small block chevys set.  the military just couldn't work it into a set.  I cannot remember the pn or nsn off the top of my head.  The problem was demand with the military, and crossing the part number from GM.  It just became a problem with paper work and most GI mechanics were instructed to use silicone or RTV instead, they had the same problem with the tranny gaskets also.

One add on also about the oil pan, is that most people forget to true up the mating surface or lip. After making sure the lip is flat take a small ball peen hammer and reverse dimple the holes. In other words strike it from the mating side towards the outside; this way if you do use RTV you're not putting a whole mess load of it on to squeeze out and look like bird crap hanging off the block. And the reversed dimples will not pierce your brand new gasket. No matter gasket or not you still have to pay attention to the four drop down corners for the crank mating surfaces with a dab of RTV. These two fixes and a good cleaning job should eliminate all your leaking oil pans A1 and A2 varients.