M923 MPG and Differential Oil Seal Leak

[gijoel]

I have a M923 truck. It went on its first major trip, 1200 miles round trip (Burning Man). Truck ran great and I got great gas mileage. I calculated about 5 miles to the gallon.. yes, 5 miles to the gallon. I even had a friend do the calculations and he came up with the same numbers. Is this right?

Prior to the trip, we had to replace the front axle differential oil seal (500177). it was a class III leak. Fifty miles into the trip, we notice gear oil seeping from the same area prior to the seal replacement, class III leak. We had a friend who is a professional diesel mechanic install it so I know it was done right. Has anyone had any issues with oil leaking from this area? We cleaned out the axle air vents so there is no air blockage… but I might add, about 200 miles into the trip, I checked the gear oil level and when removing the filler plug, I heard some air escape. Any ideas or thoughts?

 

[doghead]

I thought they were diesel.

 

[gijoel]

Doh, great diesel milage. My apologizes.

 

[Varyag]

If it still made the hissing sound when you pulled the oil plug I bet the vent is still clogged. It may be pushing oil past your seals.

 

[gijoel]

I pulled off the vent and I can blow through it. I also stuck a wooden rod down the port and it went in a few inches. I thought maybe there is another vent port somewhere else. I look at the TM later this weekend. I have to clean out the truck and power wash it. I have playa dirt and dust everywhere.

 

[Tow4]

If you heard air escape, the vent is plugged.

5 MPG sounds about right. I get 6 MPG with the M818.

 

[gijoel]

That is great news to hear 5mpg to the gallon. I think we were averaging about 5.3 and this includes hauling 500 gallons of water, 1200 lbs of ice, 1500 lbs of camping gear and another 1000 lbs in misc. supplies. I was surprise how the truck handled and although slow going up the hills, it did it at 35mph and this includes the grade from Bishop to Tom's Place. I think our group is going to be purchasing another one of these trucks. One thing I am going to do immediately, replacing the original seat. My poor back.

 

[73m819]

Instead of replacing the vent, install a vent LINE system, no more pluged vents and blown seals

 

[rrrr]

I pulled my vents and installed long rubber hoses attached to a small in line fuel filter. Works great and no issues so far.

 

[gijoel]

i am going to look at pulling all vents out and going with lines.

Today I meet with the camper engineer to design a rugged offroad camper for the bed. We plan to go over what I want, amenities, budgets, and so on. I will post pictures and keep a log of the development efforts and final product.

 

[gijoel]

Here are pictures of my M923 at Burning Man 2012. Truck was great and having lots of ice and 500 gallons of water made us a very popular camp.

 

[Dieselamour]

Hello - Does the 5 mpg consistent loaded or empty? I am thinking of buying one that has 8k miles.

 

[wreckerman893]

I thought the Burning Man event was when a bunch of weirdos got together, danced around the fire naked and howled at the moon....why would anyone want to get together with a bunch of other like minded crazy people and.........errrrrrr.....never mind.

 

[swbradley1]

I thought Burning Man was when Gimpy has one too many and tries jumping the bonfire at a rally. That makes any SS Rally a Burning Man.

 

[Scarecrow1]

These things are known to go through fuel at an alarming rate. Even the Deuces run at about 10 mpg at best. Empty are loaded doesn't seem to make any difference to mine. I know when it comes time to fuel it , just shut up and pay the nice pump That's why I have my motorcycle to balance out my carbon foot print .....Yeah right

 

[Karl kostman]

If I am on the highway at a constant RPM I can get 5 MPG out of my 925A1 on short trips into town and back (16 miles) I have found it to be more around 2 MPG
KK

 

[Tow4]

If I am on the highway at a constant RPM I can get 5 MPG out of my 925A1 on short trips into town and back (16 miles) I have found it to be more around 2 MPG
KK

 

[Artisan]

Guys I would love a material list and or pics regarding the vent lines.
I would like to know what the hole tap sizes are
so I can get materials together and do mine when I go up there next .

Is it 3/8" NPT or what? Did you just go w/ maybe a 3/8" MNPT X Barb
brass fitting and hose w/ a filter of choice up high?

 

[Bighurt]

If I am on the highway at a constant RPM I can get 5 MPG out of my 925A1 on short trips into town and back (16 miles) I have found it to be more around 2 MPG
KK

Is that with those new tires?

 

[Dieselamour]

Thanks for the info. My thoughts are that if a $60K F350 quad cab 4X4 gets 12-ish I might as well get something with similar mpg for $5K.