New Member: I'm loving my 5 ton but Brake failure!

[Brad85]

First off its a pleasure to be here and i hope all is well!

I have a rather odd question haha if you get a min to think it over and let me know your thoughts i would really appreciate that.


Came across your again page when looking for some help. I have that M52 6x6 pics attached. Long story short when I got the truck it ran well but it did have a bad brake master cyl. I rebuilt it and bled the brakes. Problem solved. Had it for about a year now and drive it to the local watering hole and whatnot and everything seemed well.


Then last night I was moving it from a peculiar parking spot on a steep hill I jammed it up on a bank. I parked it there to get it outa the way for the garage i was digging out. When I got in it fired right up first pull and i let it sit and idle for about 10 min. Normally when I hit the brakes I hear a release of pressure (pshhhhhhhh) this time i didn't?.... But the brakes seemed firm and I was only moving it from the hill back to the driveway so i went for it (Bad thinking on my part)


When pressed brakes they seemed firm so I took it outa gear it began to roll,(bad idea) immediately we were rolling backwards.I had to swing her sideways backwards into the neighbor's yard where I ran down several trees. No damage seems to have taken place but I still have no brakes. Stuck in a sinking mud runoff hole i landed in I winched myself out of the mud hole yard and back to the street and then drove it up in the driveway where she sits. But I still have no noise like usual when pressing brakes and the pressure says 120ish.... Im still confused as to why i didnt hear the (pshhhh) when i pressed the brakes (obvious i shouldn't have moved it like that).



Any ideas on what this could be or what i may need to get to fix it? Thanks again!


[FONT=&quot]Brad[/FONT]

 

[Artisan]

What happens when you do the C.O.L.A.S. test?

 

[swbradley1]

Probably your air pak. I would start with a review of the TMs and familiarize yourself with it and the operation of the truck.

 

[Brad85]

I was unfamiliar with the COLAS list but have since found it and read it over. I am not really sure about the red and yellow buttons but i can tell you that the low are light indicator is on i believe. This is a 1975 model 5 speed manual. SwBradley1 i am also unsure about the air pak ill have to look into that. I was mainly thinking perhaps i had somthing break in the freezing temps. Or perhaps something ioverlooked.

Again there is no (phssssss) when pressing brakes yet the gauge reads 120- 125 psi.

 

[swbradley1]

Does it have full air brakes?

 

[Brad85]

Its Air over hydrologic. Also i read something about an air spring override but i cant seem to locate that and not sure if that would have done me any justice anyways.

 

[swbradley1]

It still sounds like the air pack. My 5-ton makes the air noise but when I got it it didn't and it was the air pack. Sometimes they don't do well sitting for a long time either.

 

[Brad85]

Another option i may have to consider is shutting the truck off and manually attaching an air compressor to the system and filling it up to listen for leaks. Has anyone done this with success ? Im trying to troubleshoot here but being honest im new to this and new to these "big truck" issues. I am mechanically inclined tho and build and restore other vehicles so if i was given a lil shot in the right direction ill be happy to test and report any ideas.

 

[Brad85]

Do you possible have a link to the diagram and a product listing i could look at ? thanks again man!

 

[Scar59]

The COLAS test is not applicable to your series of MV. COLA, test the integrity of a true air brake system. Your M52 is air over hydraulic, basically, air pressure assited hyd. brakes. As SWB mentions, check your air pac. Drain the moisture from the system, check master cylinder fluid level, and test on level ground. Be prepared to engage hand/park brake. Do not run over neighbors stuff. Report back
JC

 

[porkysplace]

[h=3]TM's for the M39 Series 5-ton[/h]

 

[Brad85]

hahahaha my man great answer and i was sure about the air over/ hyd. system i knew that much. Now its on level ground again and its parked on a flat spot. I had it sitting in 2-24 degree snow storm and also those temps for about a month without running it. Got a new batter 1 of 4 was dead. replaced it and fired right up. Also i knew the colas system was not applicable when i looked it up. So double thanks.
Are there any video's or direct images of how i can drain the moisture from this system? Thanks guys!
Also is this the part you are referring to ? http://www.eriksmilitarysurplus.com/rekitform55t.html

 

[swbradley1]

TM's for the M39 Series 5-ton

Everything you need and more is in Porky's post. Start with the -10 and then go hog wild in the rest of them.

 

[Warthog]

This is what you have

http://www.eriksmilitarysurplus.com/airpack.html

 

[swbradley1]

http://ccsurplus.com/content/air-pack-m54-m809-series-5-ton-trucks

 

[Brad85]

That should be the one then. I would like to try and drain any moisture from it and see if that fixes it before just replacing parts if i can get away with it. Everything on is it overkill so it makes sense it should last. Also my thought process (stupid as it may be) tells me if it worked when i parked it then its gota be somthing simple... It was parked on a steep incline and brakes were left in parking lock ( added on later ) but still works well.

 

[Scar59]

Brad,
Yes, that would be the kit. If you have not drained the system, and I believe you have not, because you haven't seen the video, you NEED to get the Operator Manual and read it. The drains (petcocks) are located on the bottom of the air tanks, They may be plumbed to a petcock under the drivers step. Open them with air pressure in the system. It will need to be above freezing for this to work. Stand back, do not get that funk in the eye or mouth. Report back.
JC

 

[Brad85]

Thanks Scar59 That was what i was looking to do, Ill try and find the proper process in a link and follow that. Also looking for a good video tho perhaps i will make one to share once i understand the process. And no i have not drained it since i got the truck a year ago haha so im sure that might be the leading issue. This is somthing i do every few weeks on my big compressor so im sure this it no different in that it needs done more often. Def make sure i dont get the funk in my eyes

 

[porkysplace]

That should be the one then. I would like to try and drain any moisture from it and see if that fixes it before just replacing parts if i can get away with it. Everything on is it overkill so it makes sense it should last. Also my thought process (stupid as it may be) tells me if it worked when i parked it then its gota be somthing simple... It was parked on a steep incline and brakes were left in parking lock ( added on later ) but still works well.

Are you refering to a line lock added to the brake system ? If so they are not designed to be used as parking brakes . Keep in mind these are single circut brakes so any leak means complete brake failure . As swbradley pointed out you really need to read the -10 manual before you do anything . The air tanks need to be drained DAILY by the way. You also need to check the brake fluid regularly . Does it still have DOT5 in it as you cannot mix brake fluids ?

 

[Recovry4x4]

It would be better if we started with exactly what you have there. In one post it's an M52 but in another post you indicate that it's a 1975. I realize that the brake systems are the same but any info you provide helps us. Diagnostics. Did it build air pressure? Do you have an air pressure gauge? Its possible that one of the air lines or valves failed. The super hard pedal is a classic indication of an air failure.