HappyCamper

In October, my wife and I decided to do to the Grand Canyon. At the time of the decision we were going to take the truck and trailer. It turned out that we didn't, but that is another story.

I had part of a Saturday to make sure everything was ready. I knew that I wanted to adjust the valves and I had a few hours so I thought I would go for it. I read the appropriate stickies and did the right searches... That went well, but...




When I had started to take the Valve Covers off, I noted that the Master Cylinder (MC) and the Vacumn Booster was not looking good. I was a little frustrated because I has replaced the MC last year. The MC was probably good, but the lid was not tight and it was spewing forth with the brake fluid.



So a long story short, I managed to find the MC and Booster as separate items at the same place, but I had to travel 20 miles to get them. So, with the parts in hand I started.

1. Disconnect the vacumn hoses




2. Remove the Brake lines from the MC


3. Remove the MV to Booster nuts. Note: The brake lines are just sitting in place in this picture.


The booster is now free. Note how the paint has been eroded.


(cont. below)

HappyCamper

Inside the cab, under the instrument panel:
4. Remove the retaining clip holding the rod in place. The manual suggests that you use a new clip. I did not have one so I was real careful taking this off. With a smaller flat blade screw driver, it goes real well. Just ease the tang over the head as you work the clip off.


5. Remove the four nuts holding the booster to the firewall.


From the engine compartment, the booster can now be slid out.

On my replacement, they did not provide the seal, but the seal was in good shape so I reused it. It is on the new booster on the right. I was unsure of how to adjust the rod between the MC and the booster. So I just left it. It turned out to be perfect.


Installation is the reverse order to the point of brake lines. I was trying to decide if I should take the MC around the house to the shop and mount it in my vise and bleed it. I decided that I could do it just as well in the truck if I used care. Note that I have the lines in. I had my wife help with gently pushing the brake pedal while I added fluid. If I did not have help, this would have been done on the bench.


I made sure that all bolts were tight - MC to Booster and Booster Mounting are "200 in lb (23 Nm)"

I then adjusted the rear brakes as they were loose (I don't back up hard enough to kick the adjusters on). I then bled the entire hyralisc brake system - ABS, RR, LR, RF, LF. I should have done that years ago. The fluid was ugly!!! As I did not have a pressure bleeder, my son helped with the bleeding. Maybe it was overkill, but I used two quarts of fluid before I was happy that I had clean fluid in the system.

It has now be a few weeks since I have done this. I thought I lost the pics, but I found them so I thought I would write this up as I did not see it done. What I have noted in driving the truck is that I actually have power brakes Well as good as these truck ever had it anyway. It certainly takes less effort than before. I think that the old booster has be gone for a few years...

wannadiesel

Stuck.

Nice writeup.

NotEnufGarage

Shouldn't the bleeding sequence be - ABS, RR, LR, RF, LF?

Furthest to closest (and ABS first).

grandpa ralph

anybody know where to get the seal for the back of the booster?

HappyCamper

Thanks for the catch. It is supposed to be ABS, RR, LR, RF, LF. Tha is the way I did it, not the way I wrote it.. I will edit.... (I'm left handed and will sometimes mix my left and right )

HappyCamper

Thanks Dave. It is a small contribution to this community of really helpful people!

AUGIE DOG

Happy, you posted this just in time! I have the same problem. Have to add brake fluid every 4 to 6 months.I changed covers but it still leaks. I have a booster to swap out. I would like to do a hydro upgrade some day....Augie

Cactus92

can somebody fix the pics? on my screen they are not showing up