Brake bleeding trouble- 67

[Brandon K.]

Hi all. Thanks to everyone's help I've finally gotten my 67 L79 started. Unfortunately, I'm having a horrible time getting the brakes bled (power brakes). I bled the master cylinder, hooked the lines back up, and started at the right rear wheel. I tried both with a mityvac and manually bleeding, and I don't seem to be making any progress. With someone pushing on the pedal and a hose hooked to the bleeder with the other end in some fluid, I'm not seeing any bubbles coming out. I have checked all the blocks and fittings and can't find any leaks. Everything in the system is new (calipers from Vette Brakes, M/C rebuilt by White post, and all lines and blocks are new.) Does this sound like I have an air leak somewhere? or is there another problem, and how would I diagnose?

Thx!
Brandon

[Phil P.]

Re: Brake bleeding trouble- 67

brandon---did you check all the lines for blockage ? leave the master cap off and fill with fluid open the rr outside bleeder and have a beer, wait for the fluid to travel there---when it gets there then work your way up the system---i've tried mityvac with less than stellar luck so i made a power vac pump that works great---good luck,phil

[Frank C.]

Re: Brake bleeding trouble- 67

Brandon....check to make sure all bleeder valves are closed and IMO pressure bleeding is better than the Mity-Vac....Regards Frank

[John H.]

Re: Brake bleeding trouble- 67

I gave up on all the usual methods a long time ago when I got a Motive Products power bleeder; one-person ten-minute job, one trip around the car and you have a high, hard pedal; makes Corvette disc brakes a piece of cake.

[Timothy B.]

Re: Brake bleeding trouble- 67

John,

I also have a Motive Products bleeder that I attempted to use only one time and I made made quite a mess. I can see you created your own technique to hold the top plate in place. Can you fill me in how that worked as compared to the awkward chains and bolts that come with the kit?

Also, the other problem I had using the power bleeder is when done the master cylinder is full to the brim and removing the top makes a mess. Did you figure out a slick way to avoid that problem? I actually called Motive Products about that and told them that they should have dip tubes that stick down slightly into the master cylinder so that it doesn't have to fill it up so full...they didn't offer any other solution.

[Phil P.]

Re: Brake bleeding trouble- 67

i own one of the commercial power bleeders (type used at midas, a mini keg looking kind) and the mess it makes just didn't seem worth it---so i found an air pump i think it was out of lincoln---looks like a big model airplane engine---i plugged a couple of ports and added a suction port fitting---it will empty a master cylinder in about 2 minutes---once the fluid starts to flow it gravity bleeds very quickly---the mityvac will ware you out and seems to work best for closed sytem checks like on a dist. vac can---good luck,phil

[Lee S.]

Re: Brake bleeding trouble- 67

I bought the Motive Products bleeder also based on the recomendation from my good friend Mr. Hinckley. I thought I was going crazy! It was a mess to use on both my 1974 and my 1967. It just dumped fluid out the back of the master cylinder where the adapter plate wouldn't properly seal. I finally gave up and asked the wife to work the pedal. After about a half hour of no success, she said "%$*&$$#@&^%"! I think you can get the picture.

I finally ran into John at one of our Michigan Chapter events and asked him about this. He said the first thing he did was throw away all of those chains, j-clamps, and wing nuts. He said he had the piece of aluminum tubing at home and cut it the length of the adapter plate and held it is place with a big c-clamp.

Well, I didn't have any alumnium but I did have a piece of 1" x 10" wood that I cut to about 5" wide and 8" long and held it with a big c-clamp. It took about 10 minutes of bleeding time to get a great brake pedal.

Thanks John

[Timothy B.]

Re: Brake bleeding trouble- 67

Thanks Lee, and when you completed the bleed how did you remove the cover without still making a mess?

[John H.]

Re: Brake bleeding trouble- 67

Tim -

You de-pressurize, then remove the adapter very carefully with an old towel under the master cylinder. When I get around to it, I'll add about three dollars' worth of fittings and brass tubes (two) that protrude about 1/2" below the adapter seal surface that I can connect my MityVac to; then de-pressurize, connect the MityVac, open the valve, and withdraw the top 1/2" of fluid from the reservoir before removing the adapter (that's what the evacuate-and-fill adapter does on the unit used in the plant, but it's automatic).

[Dick G.]

Re: Brake bleeding trouble- 67

Brandon: Did you remember the rear calipers have 2 bleeders each, 1 inboard and 1 outboard? You must bleed both. DG

[Brandon K.]

Re: Brake bleeding trouble- 67

Thanks Dick, however I can't get any fluid thru the lines at all. Not sure that I got any of the air out.

BK

[Lee S.]

Re: Brake bleeding trouble- 67

I also take a one gallon Arizona Ice Tea bottle (they are kind of oval shaped) and cut the bottom 3 or 4 inches off and place it under the master cylinder for the entire operation. The bottle deforms easily and works into the space well.

I also take a big contractor style (Lowes/Home Depot) garbage bag and cut one side seam and the bottom seam. I use it as a big cover over the fender and engine area to avoid spills. I guess I could go to synthetic fluids to avoid this, but I still use DOT 3.

Lastly, I modified the hose on the Motive tank to about 6' long and can sit it on a mobile work table beside the car. As John states, you must release pressure before removing the adapter.