Brakes aren't "biting"

[DEV0 E30]

After pulling my engine (m50) a few times in the last month I go for a test drive and my brake pedal is very firm, but when I push the brake pedal it barely feels like there is any force on the brakes, like the caliper is barely pushing the pads to the rotor resulting in pitiful stopping distance even at low speeds.

I've been bleeding the brakes the past 2 days, but it isn't helping much.

Could this be a master cylinder problem? I really hope not because I have an E34 M5 MC, and replacement I don't think would be too easy to find or cheap.

Thank you.

[Mike B.]

I am having the same issue with my M50 swap. I think it may be the vacuum source to the brake booster.

[dude8383]

you know, im having this issue as well...i bled the brakes on saturday and the pedal feel is the same. I gotta really get on the brakes in order for them to really dig in.

im thinking its a vacuum leak or the calipers are fucked...

[DEV0 E30]

Anyone, I'll check for vacuum leaks but I think it's pretty much sealed.

[der affe]

your prob is brake booster/vac related. that is the way they behave when there is a vacume leak, usuallt right at or very near the booster.
greg

[dude8383]

your prob is brake booster/vac related. that is the way they behave when there is a vacume leak, usuallt right at or very near the booster.
greg

anyway to check where the leak is?

[DEV0 E30]

Bump, didn't have that much time to work on it today, but still isn't braking like it should.

[der affe]

spray (water bottle) some water around the leak and see if it momentarily seals itself up kinda like a intake leak. if you have shop access use the smoke machine to fill the vac lines see where the smoke comes out. this one might work, but since there is vac, and not pos pressure it might not, but spray windex on and arround the lines and look for bubbles.
greg

[DEV0 E30]

Just to update.

Had the damn vaccuum line reveresed. Had to bleed quite a bit to get out all the air I was letting in since the check valve was reversed.

[dude8383]

Just to update.

Had the damn vaccuum line reveresed. Had to bleed quite a bit to get out all the air I was letting in since the check valve was reversed.

woah! which line are you talking about? aren't there several vacuum lines?

[DEV0 E30]

It haven't worked under the hood of an M42, but the line that goes from the intake to the brake booster to supply the vaccuum. I thought the angled connector worked both ways or at the least had it right, but it's a valve that doesn't let air escape from the booster once it comes in. I had it backwards.