Volkszone Forum banner

Is my master cylinder broken?

710 Views 3 Replies 3 Participants Last post by  camparikiller
Hi guys

I've spent the week replacing the brakes on my beetle, (69). New discs (front - Brembo), new calipers (with 2 nipples for bleeding - that normal?), new shoes/linings for the drums at the back, new wheel cylinders, new back plates, complete refit of hard brake lines (except the long one through the middle and the one which crosses over from right to left at the back), 4 new flexible brake hoses, front and back.

So, i've come to bleed them today and the back ones seem fine. (in that after re-bleeding them there is still fluid up to the drums) - also I can hear them operating as I push the pedal down.

However, the front ones have no pressure at all. The pedal is spongy in the extreme, and there is no liquid running through the new calipers. They have two nipples on, one at the top and one at the bottom - I've tried both (got the calipers from my loac GSF)

So, is it possible that I need a new master cylinder or is there another possible (cheaper) explanation. From reading other posts there is the possibility it might be the pushrod - how do you actually adjust this?

If its not that, is it true that the master cylinder operates both the front and back brakes independently in case one fails? If so then this might be the problem, the front half is knackered but the back is ok.

The only other thing I can think of is that I'm not bleeding them properly, but I'm doing it in the right order and the back ones were fine (I'm using a handy thing from halfords where you can bleed them on your own).

This car has been sat idle in the garage (in the dry) for 15 years. Bodywork was all redone and sprayed (see photo) and is perfect, no rust anywhere. Just needs putting back together.

Any help appreciated as usual!


p.s. long post but best to get all the info to you!
See less See more
1 - 4 of 4 Posts
You should be bleeding the fronts from the top bleed nipple (as air will rise to them).

Make sure you're actually backing the nipples out enough to let fluid through. Sometimes it takes more than you might think....

As for the master cylinder. It isn't unknown for an old M/C to pack up upon bleeding, due to the fact it's getting used to the full extent, and any signs of wear or debris soon make themselves known...it's usually the last straw for a half worn M/C.

I'd try bleeding the fronts again and see how it goes. You shouldn't need to do all four wheels as you'll have a dual circuit M/C, so just do the fronts (starting from the one furthest from the M/C and see what happens :)

As always, this is just my thoughts, and I'm quite often wrong :D
Seperate one front brake pipe from the brake hose, master cylinder side, then see if you get a good flow of fluid through the open end of the pipe when you bleed.
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.