The Stovebolt Site Forums The Shop Area Driveline Brake Bleeding Questions/Issues

Hi Everyone,

I've run into an issue bleeding my brakes and thought I'd reach out to you all for help.

The background: The truck is a 1953 3100. I've spent the last couple of months replacing the brake system components with new versions of the originals (new master cylinder, hard and soft brake lines, wheel cylinders, shoes, springs and retainers). The only parts from the original system that are reused are the brass blocks and the banjo bolts, although I did replace all of the copper washers around the blocks.

Everything is installed and the system was filled with DOT 3 brake fluid. I started the bleed process using the fill and pump method, but forgot to add more fluid and pumped the master cylinder dry.... Then I lost my helper, so I bought a mightyvac. I did have some vacuum issues with the mightyvac, similar to others who have already posted about that, but it did draw some vacuum and some fluid to each wheel cylinder. Not knowing exactly what the fluid would look like when the system was completely purged of air, I filled the reservoir after doing each wheel and tried out the brake pedal. The first pump was rock hard. Then each successive pump got softer and softer until the pedal could be pushed to the floor. I looked for leaks and found some minor ones, which I corrected. Refilled the reservoir and had the same thing happen as the first time. Hard to push at first, then softer and softer. However, no more leaks.

So I assumed that I still had air in the lines and decided to redo the bleeding with the mightyvac. To deal with the vacuum issues, I took teflon tape and wrapped the upper half of the bleed valve. That seemed to cure most of the vacuum issue, although I think that I might be drawing some air around where the tube goes into the rubber fitting that attaches to the bleed valve, but it does draw a solid vacuum (25 lbs).

Now the problem: I am getting tons of air bubbles through the hose on the mightyvac. More than I expected. This time, though, the bubbles are really big, instead of the really small ones which were associated with the vacuum leak.

I've made really sure to maintain fluid in the master cylinder after the first mishap. Now I'm wondering if the mightyvac is finally drawing our the air from the lines or if there could still be a vacuum leak somewhere.

Questions:

1. How will I know when the line is completely purged of air? Assuming the mightyvac is working properly, will the fluid that comes out fill the tube and be free of bubbles?

2. Many people mention "pumping up" the system. I thought that if the system was completely purged of air, that the pedal would be very hard to push once the system was completely filled and the cap installed. What does pumping up the system mean?

3. I couldn't find anything in the shop manual about exactly how full to fill the reservoir. Is there a correct level? If so what is it?

4. During the removal of the master cylinder cap, I accidentally broke the gasket. I am still fitting the gasket around the cap when I install it, but am now wondering if the gap in the gasket could be letting air into the system. Is the gasket around the fill cap on the master cylinder critical to correct operation?

I should have stated up front that I'm a noob. You probably figured that out after reading this rambling post. So, I welcome everyone's ideas and suggestions. The truck does not currently run. I'm working on the brake system now. I have a new wire harness that I hope to install this winter and I hope to install my spare (and running) 235 this spring and actually have my truck move under its own power. I'm doing it this way because I know if I install the 235 now I'll want to drive it. Stopping is important, that's why I'm doing the brakes first. So I want to get it right and appreciate everyone's help!

Thanks,

Mike

OBTW, There are tons of pictures of what I've done with the brakes at my photobucket page and on my blog.

did you bench bleed the M/C before you started?

Did you properly adjust the shoes before beginning the bleeding process?

I did not bench bleed the m/c and am not sure what that means... other than uh oh!

when I installed the shoes, I set the adjuster to the minimum. I did not make any other adjustments.

Master cylinder needs to be bench bled before installing. Google "bench bleeding a master cylinder" and you'll find several videos and articles.

Shoes need to be properly adjusted before bleeding. If shoes are not adjusted you may push a cup out of a wheel cylinder, creating a mess and most likely ruining the shoes.

OK, I'm going to attempt to adjust the shoes (tomorrow or Monday). If I'm reading the shop manual correctly, I should do the following procedure:

1. Remove wheel and use the lug nuts to secure the drum to the hub.
2. Loosen the anchor pin nut (I assume this is from behind the backing plate) enough so that it (the pin) can be moved slightly.
3. Adjust the brake shoes until a heavy drag is felt on the drum.
4. Tap on the pin and backing plate and determine if drag changes. If it does tighten the adjuster some more and repeat until no change in drag occurs.
5. Tighten anchor nut to 60-80 ft lbs.
6. Back off 14 notches on adjuster and check for freedom from drag. If drag is felt repeat entire process.

I included the text just to be sure this is what I'm supposed to do for adjusting the shoes. Since I have a 1953, I have to go to the supplement in the back of the shop manual and sometimes I get confused. Is this the correct procedure for adjusting the shoes?

As a side note, how difficult is it to get the nut on the anchor pin loose? I didn't touch it when I was replacing the shoes/springs. It seems pretty stout to me and I'm a bit concerned about being about to break it loose... I have no idea if it has ever been touched since it was at the factory.

The 1953 brakes are like the 1954 brakes (1/2 ton).

This shoe adjustment procedure should be OK.

Hard pedal at first, then successive attempts get weaker until the pedal goes to the floor, and you have no leaks, is indicative of a bad "brand new" master cylinder (all too common these days).
I would remove the master cylinder, disassemble it and look for damaged surfaces or rubber parts.
Carl

Carl,

I can't tell you how discouraging that would be. It is very difficult for me to find time to work on the truck, let alone redo work because new parts are defective. Then there would be the expense of either buying another new MC or a rebuild kit to rebuild the brand new part. It is discouraging to hear you say that it is all too common these days.

For the immediate future, I'll try to adjust the shoes correctly and give bleeding another try. If I continue to experience the same pedal issue after correcting the adjustment and bleeding, then I'll follow your advice and take it apart for inspection/repair.

I'll let everyone know what happens, although it will likely take me a while to get everything done. If it turns out to be a bad MC, then I'll rat them out so no one else wastes their money....

I don't understand why the mighty vac doesn't pull air in through the wheel cylinders in the process. I always bleed my brakes with a tube and bottle and no helper. I have never had a problem.

Truckernix,

I think that is what I'm going to do as well (a bottle, tube and no helper). It can't go any worse than my previous attempts.

I've had good luck with gravity bleeding, even if it is a slow process.

You would definitely need all your brakes adjusted up as per the book, before bleeding. I just did my 38 Master this summer and the brakes work really well.

It's a little pricey, but nothing beats pressure bleeding. Motive Pressure Bleeder.

OK, Everyone...how in the heck do you break those anchor pin nuts free?!? Sixty years of sitting and rusting, not to mention the 60-80 ft-lbs of torque initially applied, have made those nuts not want to budge. Can I apply limited heat without damaging the new brake shoes and springs? Or should I disassemble all of the new material and then apply heat? Or should I just use more penetrating oil and an impact wrench? Any tricks of the trade would be greatly appreciated!
Thanks!

Adjusting the brakes has nothing to do with the anchor pins. The procedure is in the manual.

truckernix,

Twice I almost posted what you posted about the anchor pins.

I have never loosened the anchor pins.

HOWEVER, the 1954 3100 brakes are like the 1954 3100 brakes and I never noticed that the instructions say to:

" Step 18. At each wheel, on 1/2 ton models:
a. Loosen anchor pin nut . . .etc"

Maybe that is to get even wear on the anchor pins?
Maybe someone knows why?

Gray Ghost, you now have two of us suggesting to ignore that step.

You can, however (if you want to do so), loosen the anchor pins with a long breaker bar.

Did you loosen and slightly grease the pin-pivot inside each adjustors?

Also, the manual is unclear regarding 1/2 ton adjustment. Follow instruction "d."(page 5-12) regarding backing off the adjustment screw 7 clicks/notches.

As far as ways to bleed, I didn't see this one mentioned. Lots of ways to bleed brakes! http://www.speedbleeder.com/

My apologies about the anchor pin nut. That is new to me. It is possible I would think to break it with enough force. I don't think localized heat at the nut will affect anything else.

Setting the anchor pin needs to be done when new shoes and/or drums are turned. This procedure (see The Manual) will align the surface of the shoes with the drums. If you don't do this adjustment, your brakes will still work, but you will soon need to readjust the brakes after the shoes wear to match the drums.
Carl

Yep, that is another time the anchor pin is mentioned.

Carl,

I understand the need for loosening the anchor pin, but still have the concern about how to do so. Close up of anchor pin nut. The pic shows that there is a ton of crud helping to cement that nut in place. I don't want to break anything (old or that I've already replaced) and there is the issue of space under the truck. So, I'm kinda fumbling with ideas on how to loosen that nut the right way and not break anything and still remain safe while doing so under the truck.

Mike,

Use penetrating oil, and a good six-sided socket, and a long breaker bar (and a bar/pipe extension, if necessary).

Maybe heat a little - be careful if you have a lot of caked grease. I have only done this when I had the backing plate apart (nothing else attached to it).

That is a large bolt - it would be hard to break/ruin the bolt.

Roger that! Breaker bar and pipe extender...! I shot all 4 nuts with Kroil last night in anticipation of doing something today.

Mike,

Need I ask?
Please give us a post-breaker report.

Absolutely! I'm guessing it will go something like: grunt, grunt, grunt, craaaaaack, cuss, cuss, cuss. Repeat.

That nut/part will give you no respect for any types of grunting - a wide variety of carefully elocuted swear words have never failed for me. Unfortunately, no one has ever written a Tech Tip on this aspect of working on these old trucks.

*%%&#, **&%%&@$&*, &&!$$^I*^, *^#%^&(@^!^&&*^, &&%$#%, *^#$. *&%^$$.
That should get you started...

I am relieved that you did not provide links to sound/audio files.

UPDATE!

Anchor Pin Nut:

Mike: 4 Nut: Nil

Brake Shoe Adjuster:

Mike: Nil Adjuster: 2

I was able to break all 4 nuts loose using a breaker bar and extender pipe! After doing that, I decided to give the adjustment a try. Using the procedure outlined in the shop manual, I rotated the adjuster star wheel until there was "heavy drag". Then, using the persuader (dead blow hammer), gave the backing plate and nut/pin a few love taps. I could hear the brake shoe springs making some noise when I gave the love taps. I was assuming that was caused by the brake shoes and the anchor pin moving to center. After each set of love taps I rotated the wheel to see if the drag changed. If it did, then I rotated the star wheel a couple more turns and checked the drag and repeated the process until the drag did not change from pre love taps to post love taps. Next I tightened the anchor pin nut and torqued it to 60 ft-lbs. Then the procedure calls for rotating the star wheel 14 clicks in the opposite direction. I was unable to do the 14 click rotation with my screwdriver. So, I'm off to the FLAPS to get a brake adjuster tool....

All in all, I'm calling this session a win! I would have preferred not buying the special tool, but I had a really hard time getting my screwdriver into the slot to start with and it flat out didn't work on the last adjustment.

So now I know that making the adjustment is doable. I just need to find the time to do each wheel. Then I can get back to the subject of the original post! Bleeding the brakes....

I back off 7 clicks (1954 3100 - same brakes set-up as in 1953).

You might find 14 clicks will give you too much "pedal-play"?

Update: It was a good day in the garage. A long day, but a good one. I was able to adjust all of the brakes. Turns out, it isn't that hard. After that, I was able to bleed the brakes by myself, using the old tube and bottle method. Worked like a charm. Afterward, I tested the pedal pressure and found that there was a little play or slack in the pedal, but it did not go to the floor. It also maintained consistent pressure. The starting hard then going soft with successive pedal pumps must have been related to air in the lines. I'm guessing that I can eliminate the pedal slack by adjusting the shoes tighter. All in all, a lot of work done and now I'm off to the next project on the truck...cleaning out the interior. That'll be a separate post in the correct forum area.

Thanks, everyone, for your help and suggestions! They were invaluable.

There is supposed to be a little play in the pedal. Sounds to me like you got it right. Congratulations on a job well done.