No brakes!!

[Chris]

Well after another mammoth session today, the new cruiser is back on its wheels and running. Well it goes, but it doesn't stop. I have replaced all the calipers (with bona fide good ones off GW) and this afternoon, bled them through. No more air coming out of the calipers but pedal still going to the floor. Now I must have bled a thousand brakes and rebuilt dozens of calipers, but I have never had to bleed a master cylinder. Even when I have drained it completely.

Does this sound like the likely cause? Procedure looks simple in the FSM. Everything else including LSV looks OK. No leaks, drips or anything. Now it HAD pressure before I drained it - so I don't think the MC is stuffed. Just caught me out I guess. Any one been here before so I can walk in your footsteps?

Just to reiterate, rest of system is in very good order. Calipers nearly new or at least fully rebuilt in last thousand miles or so. Discs all spot on too. I just need to be able to sleep tonight knowing that this is all it is. I WANT THAT MOT on Monday!!!!!

Chris

 

[Brett]

Chris,

I had to replace two brake lines for my 80's first MOT under my ownership.

Just bleeding the calipers didn't result in a hard pedal, I also bled the LSPV & Master cylinder following the manual & all was good!

Have faith in the manuals

 

[Rob]

Chris if you let the system run dry then you might have emptied the ABS pump and that is tricky to bleed, might have to drive in a way to engage the ABS and them bleed again. Might have to do that a few times. Im sure there is a way of doing it properly but unsure how. Otherwise bleed the master cylinder as you said.

 

[karl webster]

Chris

Have you also blead the load sensing valve on the rear axle.

Ive had probs bleeding in the past and that could be part of the prob

karl

 

[Chris]

Done that Karl. There is no air coming out of any of the bleed nipples. Rob, ABS light did come on too. Hmm, well I'll go for the Master Cyl in the morning. The FSM says nothing about the ABS pump. Let me get some pressure in the pedal and then see where go. Can't be that tricky.

Chris

 

[Rob]

AFAIK the FSM that covers bleeding the ABS pump is not in PDF form. I think it was released in 1995, Julian Voelcker has a hard copy.

 

[Chris]

Hmm, that I could do without. Let's hope it's not that complicated. Remember that running out of fluid is a pretty predictable eventuality. It's probably not going to be that tricky.
Let's hope the ABS plays along in the morning.

C

 

[Keith Shuttleworth]

Chris if all else fails...Try opening the bleed valve on each wheel and with a couple of screwdrivers or suitable levers push the calipers back into the housing then lock of the bleeder valve, then with the levers still holding the calipers back bleed the brakes as normal. Hopefully when all done after a few pumps the pedal should build up.

 

[Chris]

Cheers Keith. That's not it I'm afraid. The pistons were pushed fully home before I started. I always do that. This isn't air in the pistons / calipers. That's just as sort of spongy feel. Like I say I have been bleeding brakes since I was a lad. This is no pedal pressure at all. Not just not very good brakes - like NO brakes. I reckon as has been indicated, it's the master cylinder that has air in. The fluid running out of the pots is clear. I've shoved nearly a litre through them.

Just find it odd that in all these years I have never had to bleed the master on any vehicle. But it has been standing empty for a couple of weeks now.

Chris

 

[Chris]

Well, fancy that

Went to the car this morning ready for another day of bruising and it appears that to a greater or lesser extent the master cylinder has bled itself. I guess there is the potential for bubbles to rise up into the reservoir over night. But pedal is hard and doesn't creep anymore. Obviously I won't take this as read and will check it all through, but it feels quite normal.

So if it's OK I can spend the the day on other stuff!!

Chris

 

[adrianr]

Result. Hope it stays fixed!

 

[Scott]

Excellent! The 80 has finally decided to assist, rather than resist it's return to active service after it's 8 year hibernation.

Good luck with the rest of the days tinkerings.

 

[sae70]

You're keen Up & out before 08:00hrs on a Sunday

 

[Chris]

I was on it at 06.45 Steve. Still not got it sorted. Something is trapped in there and going round and round.

Just can't get rid of the creep in the pedal. Wondering now if maybe the seals on the master have gone. Standing for 8 years takes its toll.


Chris

 

[Scott]

Chris, when you were bleeding the brakes were you pressing the brake pedal all the way to the floor? Sometimes the master cylinder seals can be damaged when they run over the rougher part of the piston that they don't normally run on in normal operation.

I know some people only pump the brake pedal through it's normal operating range when bleeding the system, to try and guard against damaging the master cylinder seals.

Have you tried an ezibleed brake bleeder? These can be very useful for forcing trapped air out of a system, without having to operate the master cylinder.

The ezibleed has worked for me before when all else has failed trying to bleed a hydraulic clutch system that had air trapped in a damper built into the system.

I don't think the ezibleed kit comes with a cap that fits the 80's brake reservoir, so some improvising, or adapting of a spare reservoir cap is needed.

Good luck, hope you get it sorted in time for the MOT.

 

[Chris]

Scott, I have tried Nick's ezibleeder. What a complete pain in the a55. You're right they don't fit Toyotas. We had all the extra caps that you can buy. Ended up with fluid absolutely everywhere. Spawn of the devil that thing was. Now when they fit - they are brilliant.

Anyway, never heard of the rough / smooth argument in the MC. Hmm. Bit late I think. I can't believe I have come so far in so little time. I have got just about every darn thing working. Had to replace the bus in the end of the gear selector rod today. Couldn't get the lights on the dash and the shift stick to line up with the gears. Replaced window motors, fixed main beams - some weird bulb no one had ever seen so had to make a new adapter harness and put H3s in. Got bumper back on, polished the glass!!!!

Barely a thing left to do except for the fnurking brakes. Shattered and disappointed. Sure this isn't just some air in the lines. It's behaving really strangely. And making odd noises too. I have to say that when you get pressure the pedal is solid. I mean rock hard with no creep. They you start the engine and the pedal goes to the floor. Bleed one corner, rock hard, then the next - loose all pressure. It's been making clanking noises that I can feel coming down the brakes lines. Then next time it doesn't do it.

Beer.

Chris

 

[sae70]

Chris, when you were bleeding the brakes were you pressing the brake pedal all the way to the floor? Sometimes the master cylinder seals can be damaged when they run over the rougher part of the piston that they don't normally run on in normal operation.

I know some people only pump the brake pedal through it's normal operating range when bleeding the system, to try and guard against damaging the master cylinder seals

I had this many moons ago (MkV Cortina), didn't damage the seals though, but turned them inside out from what I can remember

 

[Chris]

Spoken to Lord Voelcker who says it's classic master cylinder seals. Nothing else it can be given the rest of the history. Standing for 8 years in manky old brake fluid - then having me pumping away at them. Well, fill in the blanks.

I kinda knew it would be but always worth grasping at that final straw in case I missed some details somewhere.

Chris

 

[Scott]

It's a shame, seeing as you've come so far. As you said, the finger of suspicion was pointing at the master cylinder. At least it failed on your drive, and not out on the road.

Hope you can get the bits from Milners and still make the MOT appointment.

 

[Chris]

£50 from Milners. Looks complete. Just bolt on. No one to bleed the brakes though!!

Will nip over in the morning and get one ! think. Cheaper than the parts to rebuild mine.

C