M45a2 brake problem.

[Jess lynch]

I have truck that is making no sense to me regarding the brakes. The guy I got it from said the brakes needed to be bled so I had a friend of mine help me who used to do brakes on buses. We started on the passenger side rear and worked our way forward from the master cylinder as required. By the time we got the driver's side front dual it got stiff like the brakes were fully bled but hadn't gotten the the fronts yet. The brake pedal will not budge at all. I do not have a power bleeder so we were doing it the old fashioned way. I can get fluid out of the bleeder off of the airpac with the brake pedal no problem. Even with air pressure built it's not working. I put in a new master cylinder thinking that was it but no go. Any thoughts on why I m not getting any brake fluid past the airpac to the brake lines?

 

[jeepin]

The airpack can fail and cause all wheel lock up. With the brakes pumped/ locked up, try opening bleeders on airpack and see if brakes release to narrow it down. Rebuild manual here https://www.steelsoldiers.com/threads/air-pack-rebuild-manual.118450/

 

[NY Tom]

What is the condition of your rubber lines? Have you changed anything else on the system?

Depending on which air pack you have the kits are readily available and it is not too difficult.

 

[Jess lynch]

What is the condition of your rubber lines? Have you changed anything else on the system?

Depending on which air pack you have the kits are readily available and it is not too difficult.

Just the master cylinder. All the brake cylinders were getting fluid out until everything locked up at the pedal. The wheels all move freely with nothing hanging up. Just no pressure to the brakes.

 

[Jess lynch]

The airpack can fail and cause all wheel lock up. With the brakes pumped/ locked up, try opening bleeders on airpack and see if brakes release to narrow it down. Rebuild manual here https://www.steelsoldiers.com/threads/air-pack-rebuild-manual.118450/

The wheels aren't locked up. I bled the the airpac and the pedal still won't go down.If I bleed it at the airpack in to a bottle I get fluid out and the pedal will go to the floor it's only after I closed the bleeder at the air pack that it locks up again. So would you say the airpac is the problem somewhere?

 

[Jess lynch]

Just the master cylinder. All the brake cylinders were getting fluid out until everything locked up at the pedal. The wheels all move freely with nothing hanging up. Just no pressure to the brakes.

Still has all the original line also.

 

[NY Tom]

Sounds like an airpack problem. Sometimes a rubber line can collapse internally and cause similar problems.

Might be a good time to go thru the system. You already changed the master.

 

[m1010plowboy]

Is that the same bleed routine as the Early Deuce? I think we bled the airpak first but our TM covered the steps real clear. The Early Deuce brakes can be bled and set without building air pressure. The TM's should be here. https://www.steelsoldiers.com/forums/the-deuce-tms.113/

There was also some dual system TM but if the M45 has a single MC then this won't help. https://www.steelsoldiers.com/threads/deuce-dual-brake-system-tm.90155/

We also had the style of airpak that would take a squirt of air-tool oil in the big canister to help lube things up.....every 6 months. A solid brake pedal is usually solved by cracking a line unless it's hung up on an O-ring or broken. I haven't seen a lot of M45's so post pics when you can and welcome aboard. There are a few fire-trucks for sale and parts listed so getting parts must be reasonable.

 

[Jess lynch]

Sounds like an airpack problem. Sometimes a rubber line can collapse internally and cause similar problems.

Might be a good time to go thru the system. You already changed the master.

Yes. I put a new one in thinking that was the problem. I get fluid out of the bleeder on the airpac if I push on the pedal. After I close the bleeder the pedal wont budge.

 

[Jess lynch]

Is that the same bleed routine as the Early Deuce? I think we bled the airpak first but our TM covered the steps real clear. The Early Deuce brakes can be bled and set without building air pressure. The TM's should be here. https://www.steelsoldiers.com/forums/the-deuce-tms.113/

There was also some dual system TM but if the M45 has a single MC then this won't help. https://www.steelsoldiers.com/threads/deuce-dual-brake-system-tm.90155/

We also had the style of airpak that would take a squirt of air-tool oil in the big canister to help lube things up.....every 6 months. A solid brake pedal is usually solved by cracking a line unless it's hung up on an O-ring or broken. I haven't seen a lot of M45's so post pics when you can and welcome aboard. There are a few trucks for sale and parts listed so getting parts must be reasonable.

The m45a2 is pretty much a m35a2 but the m45a2 didn't come with a bed. It was up the the military branch to decide if they wanted a flat bed cargo or fuel body and so on. The mirrors are different is the only thing I can see.

 

[jeepin]

The wheels aren't locked up. I bled the the airpac and the pedal still won't go down.If I bleed it at the airpack in to a bottle I get fluid out and the pedal will go to the floor it's only after I closed the bleeder at the air pack that it locks up again. So would you say the airpac is the problem somewhere?

Yes, I would take apart/inspect the airpack and since it was apart rebuild it.

 

[Jess lynch]

Yes, I would take apart/inspect the airpack and since it was apart rebuild it.

Ordering a rebuilt kit next paycheck.