How to power bleed single circuit brakes on an M35A2 deuce and a half

A start to finish walk through on pressure bleeding brakes on an M35A2 and the stuff you need to do it.

[@JeffreyLiggettNixon]

5 years later and a great informative vid. TY

[@user-it6hk5zu6d]

I am one who appreciates flat out honesty and not holding words back!

[@TopShotDustin]

Good tips man! As soon as I get the system replaced I’ll be doing this.

[@tacticalrepair]

Had you in mind on this one.

[@ColdPizzaKilla]

Hey Garrett, Thanks for all of the pointers and help. This has been incredible in helping me rebuild my M35A2.

[@bkellewood6317]

Awesome thanks! M109A3 (1972yr) is what I just recently picked up and I've starting researching the brake issue I've got with it. Your video is a good start👌

[@justinritchey7621]

Thanks to this video I got my brake lines bled and the system running good, and yes that door does hurt a lot, hit it more than once myself working on mine lol

[@tacticalrepair]

Glad you got it worked out!

[@nighthawkrandy]

I always hit my head on the bottom of the drivers side mirror when I walk bye LOL

[@christian3jd]

That fitting on the cap is called a "weatherhead fitting". MAC tools offers a socket set for them. Older diesels on and off road used them. Detriot diesel used them on their 2 cycles in many places.

[@farmdawg9144]

Great info on these old beast. Your video helped us service our old M35A2. Thank you.

[@justforfun562]

Thanks Garrett!

[@bradyhanford8434]

Awesome videos thanks for sharing the knowledge!

[@johndowe7003]

you can make a bleeder with a 2L bottle just put two holes in the top, one small and the other for your rubber hose, fill the bottle up so the bottom of the bottle about 1/3 of the way up and just pump the breaks until all the bubbles come out the bottle will make an air lock and no air will get back in the system. better than buying and assembling all this extra stuff, a remote brake fluid reservoir is better for this set up. best 30$ i spent on my duece

[@gregfrench2836]

Where can I purchase brake lines for one that’s been bobbed? 72 kasier Hercules an I’m out of town an this deuce is mechanically perfect I mean everything, BUT !!!!!! when I traveled 250 miles through the Ozark’s to get it, we’ll you know, brake lines dry rotted, it’s it’s hilarious I know, but I promise you if I have to ride the E brake the whole way home and second and third gear. I’m fixing to takeoff but thought I would ask what’s the quickest way for me to get brake lines on this and bled. The video is perfect. I don’t have a problem with that or can I pick up these brake lines?? here right now trying to figure it out March 6, 2023 and it’s dark and I got a nice truck with no brakes guide me please

[@tacticalrepair]

Get on steelsoldiers.com, go down to " The Deuce" section, look for " deuce parts quick reference guide". Open that PDF file. There's a part number for civilian brake hoses you can buy that aren't a perfect fit but will work for a temporary fix.

[@user-rq8br8pi2i]

Garrett, thanks for doing these videos. I have owned a 1968 M35a2 for about 10 years. Lots of work but worth it. I replaced the Air pack but had a hard time bleeding it (I didn't gravity bleed, mistake #1) so it didn't take much fluid (Mistake #2. Anyway, thinking it must be .. (I'm not sure what I was thinking) ok. I drove the truck a couple miles. On the way home smoke started coming from below the cab and the break peddle went hard and too the floor. I crawled home using the emergency brake. I believe the smoke was from fluid leaking on something hot. My plan is to change the master (May have blown the front seal from poshing so hard on the pedal) and then bleed the entire system following your directions. Would you agree with this first plan of action? Dan

[@tacticalrepair]

Definitely look for your leak. I'm wondering if the hydraulic brake light switch didn't fail and start to burn. Would be on the nose of the air pack hydraulic cylinder.

[@longrifle.]

The brakes worked Very well on my truck, one of the main reasons I bought that particular one. You can spend a ton of money just on repairing the brake system on these trucks. Since DOT 5 doesn't absorb moisture Or isn't spose to, what's your thoughts on flushing a working system? Should it be done say annually or just when you have a reason to break the system open? Thanks Garrett keep the vids coming your doing a great job. May want to explain the difference between single and dual circuit brakes for those that don't know.

[@tacticalrepair]

I like to flush them at least once every couple years.

[@longrifle.]

Thanks. Well then its about time I do that. Were you able to buy the DOT 5 over the counter at napa? For a complete flush how much do you think the system holds?

[@tacticalrepair]

Yes I get it at Napa. Two quarts is more than enough.

[@thomasbriggs5120]

Nice video, great trick !

[@darrylarnold9745]

Hi Garrett, Watched the video which is great by the way. I've installed the external remote brake fluid reservoir. I've remoted the pressure line that connects the master cylinder to the air and closed the port. Now when I press the brakes I get fluid coming out of the overflow line under the hood. How do I fix that?

[@tacticalrepair]

That means your air pack is leaking internally from the hydraulic cylinder into the air cylinder. Time to rebuild it.

[@danielcondori8266]

Hello, I am writing to you from Bolivia. A query does not have a repair and maintenance manual for the 2 1/2 ton m35a2 brake master cylinder. a greeting and a big hug

[@tacticalrepair]

You can find links to repair manuals in PDF format in " The Deuce TMs" section on Steelsoldiers.com.

[@plcfixr2958]

Great video! I just replaced all of the brake components on my truck. The P.O. had switched to DOT 3, so I continued with that. I see your comments on the moisture issue. What would be the best way to switch back to DOT 5? If I just pour in DOT 5 and bleed it through, won't I still have DOT 3 in the wheeel cylinders? Keep up the great work!

[@tacticalrepair]

You'd have to remove everything and clean it out now. Just run it until it fails. Doing a flush every year or two with fresh Dot3 will help

[@plcfixr2958]

A yearly or bi-yearly flush with DOT 3, sounds like a plan to me. I'd really hate to pull everyrhing right back down after just going through it all!

[@bkellewood6317]

Also, i had a close call with the door as well😂

[@linarn4671]

what wrenches to use? square bolt in mine. is it easier to take the bolt out from underneath or will a 12-point socket work from the top? super tight bolt. can't seem to get a wrench to fit. Hope you're doing better over there across the pond Garret; we don't mind seeing your smiling face cooking the Korean guy grub. we sure appreciate all the help you've given over the years. you're not forgotten.

[@tacticalrepair]

I use a short 3/4" wrench from the top. A 19mm may fit better if the paint is thick. Use a prybar to lever the wrench.

[@alexmatthews6779]

So At the bleeder valves at the wheels, all you need to do is crack them open and pump up the pressure? Just want to make sue I do this right. Great video by the way

[@tacticalrepair]

Pressure first, then open bleeders.

[@alexmatthews6779]

@@tacticalrepair Thank you! My brakes were soft, but they just needed a minor brake adjustment. Thanks for showing me how!

[@johnford010]

Where does that vent line need to go? I bought a 1970 am general, and it appears it just has a plug in hand tight. The guy said he put new air pack in and all new cylinders. Brakes worked after pumping them up, but now it sat for a month, and they didn't pump up again. I planed to bleed them again but wondering if the plug is part of the issue?

[@tacticalrepair]

It is. Air needs to be able to freely move both ways through the vent. Run a vent hose up to your firewall from it.

[@lainstevens8337]

Do you have to use the lawn and garden sprayer or can you have some one pump the brakes up like in a normal car ?

[@Zachnsm1234]

Hi - would you ever want to do video about splitting the breaks system to 2 circuits, after all no one wants to drive one of these beasts without be able to stop

[@tacticalrepair]

Planned in the future, yes.

[@Zachnsm1234]

@@tacticalrepair great

[@thomasvass4486]

If you've got two people, it's the same as bleeding the brakes on any other car correct?

[@ericgentile6742]

I've did everything you said but I still don't have fluid coming out of the air pack from the first step is the master clogged up maybe?

[@tacticalrepair]

Possible and I do see that a lot on trucks that sat for a long time. I always carry a spare new master cylinder with me.

[@jeffwellette9900]

Hi Garrett, trying to bleed my brakes on m35a2. Just rebuilt long air pack and bled air pack. Rear axle, passenger side, I have put 1 gallon of brake fluid thru and I'm still getting air thru bleeder. Is this normal? My master cylinder probably has a seal issue also, it drips a little. Any insight would very helpful. Thank you

[@tacticalrepair]

Definitely suggest replacing or rebuilding your master cylinder before wasting more fluid. After that just keep bleeding. The system holds about a gallon anyway.

[@lukemaiden8702]

The power bleeder is to screw into the master cylinder bleeder and stay in there until completion, correct??

[@tacticalrepair]

No it screws into the vent fitting on the cap and stays there until complete.

[@joetherockman8755]

Can I or how do you bleed without a pressure sprayer? Can the brakes be pumped without the truck running? Thanks and great video!

[@kyllemccullah3668]

Can you upgrade a m35a2 to the m35a3 dual channel brake system by bolting on the second airpac, master cylinder, and lines?

[@tacticalrepair]

Yes. You'll also need the pedal/ master cylinder bracket and pedal assembly.

[@rossstandring8745]

Ran into a issue, cant get pressure on rear axels fronts have pressure but cant get anything from any rear wheel cylinder. Collapsed line? Thanks for your videos very helpful!

[@tacticalrepair]

You may have a line blocked internally with rust buildup. You'll want to replace all the steel brake lines on the whole truck.

[@rossstandring8745]

@@tacticalrepair Thanks!

[@fordtuff1809]

So there is no pumping of the peddle the pressurized master provides the bleed?

[@tacticalrepair]

That's right.

[@fordtuff1809]

Awesome that makes perfect sense but for some reason I was like mhmm maybe I still need to pump now next question will I need to increase the pressure at any point or it will be fine while I get to all 6 wheel ends I plan on buying the gauge/tool from big mikes he is a buddy and local to me so I will l Ls exactly how much pressure is in during the whole process

[@fordtuff1809]

Thanks for the response on this old video also

[@tacticalrepair]

@@fordtuff1809 you may need to pump some more pressure up a time or two through the process. Depends on how much air or bad fluid you have to flush out. Of you do pump the pedal with pressure applied from the bleeder you'll blow the packing out of the master cylinder, so don't do that. Yup, Mike is a great guy. Very glad to know him. Glad I was able to help you here. I never ignore comments as long as youtube gives me a notification.

[@fordtuff1809]

Ok thank you I will not be pumping while it is pressurized I was told when I got it that the guy would add fluid periodically but being I never had done it and the cap looked a little tricky at first I figured I would know when it is time to add but k was wrong on that drove it bunch of times never felt any different in brakes but than it sat in my yard for few weeks I went to go leave and had zero brakes so I’m gonna film it and bleed it and see where that takes me

[@jessesanchez7388]

How do I know if my break master syndrome is not working?

[@WolfmanJack-ol2rl]

THANK YOU GREAT VIDEOS

[@heathbratcher4394]

Question for you sir, My cap doesn't have a vent line. Will it work with out it or do I need one. If I need one, I get that it plugs into the cap but where does the other end go? You will have to forgive me, I am slowly learning about these trucks and do not have alot of experience with repairing vehicles.

[@tacticalrepair]

It will work as long as the hole is not plugged, but you need a vent line to keep debris from falling into it. You can run your own line up the firewall with 1/4" DOT air line and a 1/8" NPT to 1/4" air line 90° fitting.

[@heathbratcher4394]

Cool Thanks!

[@thecapt705]

I added an external reservoir, is there an easy way to hook the bleeder to the reservoir or should I go right to the cap on the master cylinder?

[@johndowe7003]

what tires are on that truck? g177s? also a door corner to the head hurts like hell, nearly knocked myself out on that before it made me stagger xD

[@tacticalrepair]

Yes, G177

[@phinex60]

If you have help, and bleed it the 2 man system. Does the truck have to be running, or will full air tanks and truck off be fine?

[@tacticalrepair]

You don't need air at all actually.

[@phinex60]

Thank you, get her bled and the brakes are better then when I first got her. Thank you for all the videos, they are awesome and have helped greatly on my repairs.

[@tacticalrepair]

You're welcome! Very glad they helped you.

[@edwild9161]

I have replaced the right front wheel cylinder, and the right rear wheel cylinder (at separate times) and only blead that particular location both times with good results. I've just replaced the front left wheel cylinder, and now I can get enough pressure to even bleed it, no pedal feel either while pumping the brake. Has my master cylinder or air pack failed? Also, it has the short air pack like on an M35A3. Thanks.

[@tacticalrepair]

Sometimes they are just a pain in the ass if they get air trapped in a funky spot. That is most likely your problem. Has happened to me many times and is usually solved with the method in the video.

[@alexmatthews6779]

So I am curious, I watched your other video on Cautions with the power bleeder, and in that video your bleeder had brake fluid in it, so my question is is to bleed this truck properly do you fill up the power bleeder AND master cylinder with brake fluid and THEN pump it up and bleed the brakes? Or leave the bleeder dry and just pump up air?

[@tacticalrepair]

You need fluid in both.

[@av3fire1]

great video... tried to bleed my brakes on my 66 m35a2.... no fluid comes out the bleed screw on the air pack..... even took the damn thing out and nothing...... does the truck have to have air pressure to do this? I have a slow leak and their curently is none, but i can start it and build up pressure then try again......

[@tacticalrepair]

No. No air pressure is required. You might have a bad master cylinder.

[@ericgentile6742]

I'm having the same problem please let me know if you figure the problem out and I'll do the same!

[@tacticalrepair]

@@ericgentile6742 it can only either be a bad/ clogged master cylinder or the relay valve in the air pack needs to be rebuilt.

[@ericgentile6742]

Air pack is new just ordered new master last night definitely let you know how it goes when it's finished thank you for getting back to us!!

[@mcclx4183]

What would the downside be of flushing with DOT 3 and using the cheaper fluid?

[@tacticalrepair]

Dot3 absorbs water from the air, which is rusts the hydraulic components in these systems badly. Dot5 doesn't absorb water.

[@johndowe7003]

i have dot3 in mine, it works fine just like any other vehicle. way cheaper and does the same thing. but yeah it can rust your stuff

[@tacticalrepair]

@@johndowe7003 I don't put Dot 3 in any of them. They sit and aren't driven much, so the dot3 fluid is harder on them than it is on a daily driven vehicle. The increased cost in fluid decreases maintenance and repair cost.

[@johndowe7003]

oh alright, i drive mine pretty often.

[@johnbartlett7149]

There are two schools of thought on this in SS. DOT3 and water/moisture mix so any moisture in the system will be evenly disturbed in the system, regular flushing will keep this from being a problem. This is increasingly an issue if you are in water. If you don't go in water and live in a dry environment not as much as an issue. DOT5 floats on top of water and does not aborb water or moisture, it was picked because these trucks would sit very long times and not used. It is also a better pick when the truck is designed to be forged in water. The disadvantage to DOT5 is, any water or moisture will go to the lowest point by gravity, which is your wheel cylinders and will rust them out and cause failures. This too can be prevented from servicing and bleeding the system if it's been exposed. The other disadvantage with DOT5 is the system has to be designed to use it as with some older systems (not in M35s but older military vehicle like the Willy's Mutts for example) that haven't been upgraded the DOT5 will eat the natural rubber seals. A system that can run DOT5 can also run DOT 3 after it's cleaned out but not all DOT3 systems can run DOT 5.

[@stevenbeale7318]

sam powell

[@stuntmanmike37]

If you have an assistant, can you bleed these properly with just having them pump the brake pedal while you crack the bleed valves?

[@tacticalrepair]

You can but it's not as effective.

[@jeffwellette9900]

Hi Garrett, rebuilt my long air pack and bled the brakes. It seems that some of the brake shoes are engaging the drums and I can't adjust them, neither major nor minor adjustment works. Any thoughts?

[@tacticalrepair]

They are both eccentric cams. They have to move unless you can't turn the adjusters. But when you turn one it moves the other adjustment too, so you fight it the whole time. Huge pain in the ass.

[@maryjane1231000]

How long should it take to Gravity bleed from the master cylinder to the brake booster.

[@tacticalrepair]

Not long. Just a few minutes.

[@maryjane1231000]

​@tacticalrepair what could cause it to not bleed I have a new master cylinder and rebuild airpack or do you need are pressure in the tanks

[@tacticalrepair]

@@maryjane1231000 you don't need air pressure to gravity bleed it. You may have a clog in the line between master cylinder and air pack, or the bleed screw may be clogged.

[@donaldsmith3048]

How many years were you in the military? It isn't because you know the trucks, I can tell you were in for some time. I spent a lot of time around the military, I was not in. I had 2 rods put in my back at Brooks Army Hospital at 16. Army Brat! I am guessing you were in the Army. I spent the first 18 years of my life around the Army.

[@tacticalrepair]

I never served, I just carry myself well. I was in civil air patrol in my teens, but that's all.

[@donaldsmith3048]

@@tacticalrepair I was a squadron commander, for the local squadron in the 80's. They will take people with bad back in the CAP!

[@mikesjunk]

My new Mc from mikes came with a plug type plastic cap. Is this okay or should I start sourcing a vented type

[@tacticalrepair]

It needs a vented cap.

[@kevinweston4558]

How close is the Air Pac on a m135 to those I have a m135 and have no boost

[@tacticalrepair]

It's not a direct fit but I'm sure you could make it work with enough modification.

[@boomhower363]

Is there a good way to bench bleed the master cylinder when you replace it or do you even need to do that

[@tacticalrepair]

I do bench bleed them. Put the cylinder in a vice, bend a piece of 1/4" brake line in a semi- circle back to where one end is well into the reservoir and the other is connected to the fluid outlet. Fill the reservoir and pump the cylinder with a dowel or screwdriver until no air is apparent in the fluid.

[@theironwoodtable]

Can you use a vacuum bleeder at each wheel instead of the pressure method you described? I use the Harbor Freight bleeder on my other vehicles but am not sure if the air over hydraulic system would cause an issue. Vacuum bleeder i'm referring to: www.harborfreight.com/brake-bleeder-and-vacuum-pump-kit-69328.html

[@johnnorris1615]

i saw a fellow had replaced his single line system with a dual master cylinder, is this a good idea? looked like a regular master cylinder

[@tacticalrepair]

It is a good idea, but very expensive and complicated.

[@johnnorris1615]

@@tacticalrepair screw that im a jarhead we use the KISS method... keep it simple stupid

[@justinritchey7621]

What are your thoughts on an LMTV military truck, thinking about getting one.

[@tacticalrepair]

Top heavy, overengineered, computer controlled garbage. Last of the true combat worthy trucks was the 939A2 series trucks.

[@THEFIREMANDAN91C]

Where did you get the brake lines from? Great vid btw!

[@tacticalrepair]

There was a guy that used to make them on steel soldiers, but I dont think he does anymore.

[@rjjones5484]

Tactical Repair do you think napa would carry them.

[@rjjones5484]

Tactical Repair do you think napa would carry them.

[@chadtrump7009]

How do I know if I have single circuit brakes?

[@tacticalrepair]

If your master cylinder looks like this one. If it's plastic then you have dual circuit.

[@usmcbrat7276]

Great video . Question how much pumping of the sprayer is enough pressure ?

[@tacticalrepair]

Hard to say. Every sprayer is different. Pump it to the max you would if using it to spray weed killer long distance.

[@usmcbrat7276]

@@tacticalrepair ah ok i just did not want to blow up my seal as you spoke about. also would you know why my brake peddle would not come back up even though the fluid is full and thank you for response

[@evanromero5932]

Where do u find parts

[@tacticalrepair]

Bigmikesmotorpool.com

[@dogbite082]

What tires are you running on this truck?

[@tacticalrepair]

11.00r20 Goodyear G177 radials