Can't Bleed My Brakes

[mistermeena]

So I had to replace my calipers because the fronts were leaking badly. I got a 2nd hand set and fitted them up no problems yesterday. So today I went to bleed the brakes (using the usual two man procedure) and the rears went fine - some air came out and the new fluid came through both sides so no problem at the back. But when we tried to bleed the front left we get basically nothing. We went for ages and never got more than a little air and fluid, but no substantial amount dropped through from the resi and the pedal goes straight to the floor.

I blew air through the bleed nipple and it seems to be fine. Also tried swapping the nipple for the one on my old brakes. Removed the brake line from the caliper and get basically nothing from there either, just a bit of air and fluid but again nothing substantial. So do I have a blockage somewhere between the master and caliper? Or a problem with the master maybe? In either case what do I do about it? The old brakes seemed to work ok other than a slightly spongy pedal and the fairly obvious leaks. I expected this to be a quick job so now I'm stressed!

oh and its a non-ABS r33 gtst

[PN-Mad]

Nipples pointed up on both calipers?

Wouldn't be the first or the last to install them upside down.

[mistermeena]

What do you mean by pointed up? As in are the calipers L & R on the correct sides? The nipples are at the top and pointed in and calipers are on the correct sides

[Dobz]

Try open and closing bleeder with pedal pressing.

Open bleeder and push down on the pedal. Close bleeder and let the pedal off. Repeat.

Hopefully the suction created when you let the pedal off with the bleeder closed will help draw fluid through.

The other alternative is finding a suction bleeder.

[mistermeena]

yeah we tried that already and did it for ages actually. It's as if no fluid is ever reaching the caliper, and the level doesnt drop in the resi either.

[89CAL]

Doesnt have ABS does it?

[mistermeena]

No ABS. One random question I have though is why does the rubber hose go to a little block on the suspension, then come out an go into the caliper? i.e. what is the block for?

[mistermeena]

this thingo:

[PN-Mad]

Yup! sounds like you've put them on correctly.

People install them with the nipples pointed down, and wonder why they can't get the air out....

The pistons moving freely within the caliper? They aren't all jammed and gummy inside?

[zebra]

I cannot remember

but can you bleed the master cylinder?

I remember having to do that with the clutch on the 33

[mistermeena]

It's hard to know if the pistons are ok really, they were pretty tough to compress but I got the brakes of someone I know so I trust his word that they were in good working order when they came off his car. Also, the fact that I can't get a good stream of fluid out of the hose when it's disconnected from the caliper suggests that the problem is before the caliper anyway?

Zebra: yes, there appears to be a bleed nipple on the side of the master. I didn't mess with it because I've never done that sort of thing before lol

[zebra]

Give it a go.

could be that there is an airlock

[blind_elk]

You really need to bleed the master first.

Also, try bleeding the RH caliper, see if helps.

[mistermeena]

Would it be the same bleed procedure on the master? hold the pedal down, crack it, close it, release pedal?

[Ben C34]

That block is just for mounting purposes.

[PN-Mad]

Strange to be an airlock, considering he hasn't touched the master, only take off some calipers and replaced them. You didn't let the master run dry anytime?

Try going back to the rears and bleeding them again. Thought process is to make sure the piston isn't stuck within the master.

[mistermeena]

nah was careful to make sure the resi was topped up. Will try to bleed the rears again tomorrow and see what happens. So if I get nothing through the rears the outcome is replace master cyl?

[mistermeena]

OK so I tried bleeding the rear left again and its fine. Fluid came out strong so I assume the master is ok

[Plattsy]

may sound stupid. but start the engine for a few mins and pump the brakes.

then try again.

[warps]

The master will have separate circuits and pistons for the front and rear brakes. It's possible for one circuit to fail while the other is fine. Also could be something simple like the piston not uncovering the port, or a blockage in the port preventing the master from filling from the reservoir (I had this on a 1960's Mazda about 20 years ago - tho I'd imagine MC design would have moved on since then).

Try to bleed the master, but you might find it needs a rebuild. Remember these brakes are around 20 years old, so even if they worked well on a car doesn't mean they aren't close to failure. To be safe I'd run a kit through all calipers, and even the master. But then again, I'm anal when it comes to brakes.