M923A1 front hubs smoking and air pressure in gas tank question

[TacticalDoc]

UPDATE M923A1 front hubs smoking and air pressure in gas tank question

Took my M923 (marine with fording kit) out for a ride and noticed smoke coming front 2 hubs. Seems like the brakes are on but are not really noticeable and it smells like brake pads. Also, I noticed that my air is coming out of my gas tank vent only when I let off the brake but not when I press the brake.

The straps for my fording kit have not been taken off so I don't think the fording kit is on. The only thing I was this line was broken



The first and second picture is where it broke and third picture is where it goes to. I'm not sure it's related to the smoking front hubs but I'll replace the line and see what happens.

Second picture says Air Inlet.

 

[Floridianson]

Looks like the alcohol bottel in pic three and if so nothing to do with fording. It would be used in cold weather to try and keep moisture out of the air system.

 

[gimpyrobb]

Yup, adjust your brakes and fix the alcohol feed line.

 

[TacticalDoc]

I was talking to someone on line and they said it might be the bearings in the front causing the smoke...maybe
I'll lift the front up and shake the wheel. Then I'll take the cap off and check the outer bearing.

I still haven't figured out the air pressure problem.

 

[73m819]

That would BE STRANGE if both front brakes are to tight, I would guess that either the front abs, the proportioning valve, or the front release valve is sticking, ALL three control the front brakes.

 

[73m819]

I was talking to someone on line and they said it might be the bearings in the front causing the smoke...maybe
I'll lift the front up and shake the wheel. Then I'll take the cap off and check the outer bearing.

Unless BOTH L/R bearing are bad.

 

[TacticalDoc]

Is it normal for air to come out of the lines from the t case, trans and fuel tank when the brakes are let go?

 

[73m819]

NO

 

[Floridianson]

VENTING SYSTEM OPERATION

The air venting system vents air from brake system and powertrain and fuel vapors from fuel system into air intake

stack where it is released into the atmosphere. The components of the air venting system are:

A. SPRING BRAKE RELEASE CONTROL VALVE
- This valve functions as an override when a failure in

the air supply system (causing spring brakes to engage) occurs. When valve is manually pushed in,

emergency air is supplied to the spring brake chambers. This releases the spring brakes, allowing

vehicle movement.

B. PEDAL VALVE
- Vents primary or secondary signal air pressure when pedal is released.

C. FRONT BRAKE CHAMBER VENT
- Vents air pressure inside chambers when pedal valve is released.

D. LIMITING VALVE
- Vents signal air pressure going to front brake chambers so rear brakes apply first.

E. STEP BOX QUICK-RELEASE VALVE
- Vents air pressure from spring brake chambers when parking

brake valve has been actuated.

F. REAR BRAKE CHAMBERS
- Vents ports on chambers to prevent air pressure buildup.

G. RELAY VALVES
- Vents air pressure in rear brake chambers directly to intake tube when brake pedal

is released. Vents signal air pressure through upper port in valve.

H. AIR INTAKE STACK
- Venting point for the vent system.

I. TRANSMISSION VENT
- Vents internal air pressure buildup due to internal heat.

J. SPRING PARKING BRAKE VALVE
- Vents air pressure from air and double check valves No. 3

and No. 4.

K. TRANSFER CASE VENT
- Vents internal air pressure buildup due to internal heat.

L. FUEL TANK VENTS
- Vent fuel vapors to prevent partial vacuum from stopping fuel flow.

I have not worked on this system yet but as stated it is all vented to intake stack. I don't know if there were a blockage in you system somewhere guess it could come out the Deisel fuel tank.

 

[jdknech]

I had the "smoking wheel" problem on my M932a1, turned out both front bearings failed... The driver side had no rollers left on the outer bearing, and the passenger side wasn't much better.. Shaking the tire won't tell you much on a tire that heavy, it just won't move.. Pull the cap off of the hub, jack up that side, and use a pipe under the tire to lift it up and down to see if the is any movement in the bearings..

 

[TacticalDoc]

NO

what would cause that? other than the fording kit being on?

The only way I knew is because I bypassed the lines behind my cab

 

[Floridianson]

Blockage in the last line that goes to the intake Maybe.

 

[TacticalDoc]

I had the "smoking wheel" problem on my M932a1, turned out both front bearings failed... The driver side had no rollers left on the outer bearing, and the passenger side wasn't much better.. Shaking the tire won't tell you much on a tire that heavy, it just won't move.. Pull the cap off of the hub, jack up that side, and use a pipe under the tire to lift it up and down to see if the is any movement in the bearings..

Had someone else tell me that it's the bearings too. I guess after 30 years they go bad. Are they the same bearings as the rear? If so I happen to have a pair of new ones.

 

[crasheej]

Could be. Pull it apart and then you'll know what the problem is. I'm having trouble shooting from here.

 

[TacticalDoc]

Could be. Pull it apart and then you'll know what the problem is. I'm having trouble shooting from here.

Hard to pull of the hubs with one person...anyone want to help
lunch/beer on me

 

[doghead]

It's a one man task.

 

[Dr.Jay]

If there is blockage in the vent lines, this can cause the brakes to hang. When you release the service brakes (raise your foot off the pedal) , the air must vent to atmosphere.

Mud wasps (dobbers) can plug a vent tube in a very short amount of time.

 

[swbradley1]

Had someone else tell me that it's the bearings too. I guess after 30 years they go bad. Are they the same bearings as the rear? If so I happen to have a pair of new ones.

How hard is it to type in M939 wheel bearings into Google?

http://www.bigmikesmotorpool.com/products/outer-wheel-bearing-for-5-ton-m54-m809-m923-ms19081-181
http://www.steelsoldiers.com/showthread.php?116306-M939-A1-and-A2-Bearings-and-Hub-Seals

 

[doghead]

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[gimpyrobb]

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