1980 brake issues

[cevallos.j]

Hoping someone can help us as we seem to be out of ideas! We got this car not running and now everything is ready except the brakes. I rebuilt the calipers, tried bleeding and had lots of air coming out of the master cylinder reservoir and no brake pressure, peddle went straight to the bottom. Assuming it was a bad master cylinder we replaced it with a new one and now we have absolutely no brake pressure when trying to bleed. Any one have any ideas? There is a hose in the engine compartment (engine is out) that air comes out of when we pump the brakes..

Hope someone can help!!

[mreid]

That hose is the power brake vacuum line. Easiest approach is to use a power bleeder that screws onto the reservoir. That way you can tell if you have a crimped line or obstruction.

[JOHN21BLACK]

Use a vacuum bleeder. Start with the pass rear first then driver side rear, pass front, driver front. Dont worry about hose for power assist. The vacuum bleeder i used from harbor freight work fine. Hooks up to bleeder screw. Cost 30.00. Well worth it. No need for help.

[Bob Kontak]

Originally Posted by cevallos.j

Any one have any ideas?

I have an idea. Did you bleed the master cylinder on the bench before you installed it?

I'll bet not since you did not mention it.

[timmy2]

Block of wood behind brake pedal so you don't go past MC travel range when bleeding?

[cevallos.j]

So I got a vacuum bleeder and when we first started doing it first some brake fluid came out but then it was only air, I guess this means I have a leak...

[Jeff Burger]

could you have mixed sides on the calipers? the bleed screw should be on the top .

[Westy]

I can't speak for Porsche design, but almost all other Master Cylinders will have air behind the plunger. (Usually) it's a must to bench bleed the thing before install. If not that air pocket will just sit there and halt any attempts you make to flush the air out of the lines. I wouldn't bench bleed with it in the car (hence the phrase 'bench bleed') or you'll have quite a mess.

[cevallos.j]

I checked and they are on correctly. Seems we can't get any fluid to go through the master cylinder. Only air comes out of the bleed screw. I will try bench bleeding next as we didn't do that.

Thanks guys

[cevallos.j]

Jeff Burger you were the life saver. I thought we had checked but you are right, the fronts were backwards! Problem solved !!!

Thanks to all!

[Avanti]

Just curious, did you bench bleed the master At the same time you swapped the calipers or did you bleed the master with no luck in getting pressure then swapped the calipers and then got pressure? If the former, the no pressure problem was caused by not bench bleeding the master first. The calipers upside could cause the problem of not getting all the air out of the system (air rises) but would still have pressure and be squirting fluid.

[cevallos.j]

We didn't actually fully bench bleed, we "bench bled" kind of with the master cylinder installed, but didn't get any improvement. Swapped the calipers and immediately got pressure. Then re bled the brakes once or twice and they are working really nicely.