Morris Minor Owners Club

Rear brake cylinder problem on my pick up.
I've bled the system again using Eezibleed. Put a full bottle of fluid through to each wheel, NO bubbles coming out. Still had a spongy pedal.
I clamped off the rear brakes at the flexy in front of axle ...resulted in a very SOLID pedal.
Therefore ...the problem is definately air trapped in rear cylinders.
Looking at my photo, and the relative position of the bleed screw, it's not hard to see why you can't properly bleed these cylinders.
So, how do I prime the cylinders and succesfully bleed them?
I've done a search on here and have found bits of info on this, but I'm not sure whether my set up is the same as others (and I couldn't fully understand the suggested process).

The set up regarding the brake cylinder and bleed nipple is factory correct.
Have you checked the condition of the rear flexible brake pipe?
Morris Minor rear brakes either bleed easily of are a right bu--er to bleed.
In the past I have had to raise the rear of the vehicle as high as possible and then either leave overnight before bleeding or bleed after raising the rear of the car.
There is little if any chance of priming the rear brake cylinders.

Thanks Phil
I'll check the condition of the flex. Also it does actually look longer than it needs to be (see attached).
I've had the back end lifted for a few days and that didn't help.

Thank you for the picture.
The hose does look to be extra long but where and how it is fixed either end I do not think you could get away with a shorter pipe.
When I said high I meant having the axle at least waist height.

I wonder if the rear bleed nipples were left open for a good period of time, that any air bubbles in the cylinder might naturally rise and find their way out.
I seems that if just pumping fresh fluid from the pedal, it will all just go straight out of the bleed nipple and leave any air in the cylinders undisturbed.

I have never tried this, just wondering if it is feasible, as not many of us have the facilities to get the back axle up to waist height.

Phil P

philthehill wrote: ↑Sun Apr 18, 2021 8:26 am Thank you for the picture.
The hose does look to be extra long but where and how it is fixed either end I do not think you could get away with a shorter pipe.
When I said high I meant having the axle at least waist height.

Yes Phil, I've had it that high previously.
I would have though that any rising air bubbles from front to back of car (with back higher) will just collect in the loop of the flexi as that is still the highest point in the system (higher than the rear cylinders).

Actually, that's just given me an idea! Maybe the high loop of the flexi is where the air pocket is?
When I clamped the flexi I clamped it at the front end of it which would give the resulting firm pedal.
I'll try bleeding it with loop pulled down lower and see if that helps.
FINGERS CROSSED!

When you bleed give a good stamp on the brake pedal to thrust any air to and out of the bleed nipples. You will need someone to quickly shut the bleed nipple when the pedal is down and do not allow the pedal to rise until the bleed nipple is tight.
Good luck.

Is it possible it's the flexi expanding giving a soft pedal? I know my brake pedal was transformed once I replaced all 3 flexis-i had a much firmer pedal

Just a possibility. After replacing all brake hoses (the rear one was balooning) and after three bleed sessions and my "tame mechanic" being assured that no ore air could be bled out of the system, I still had a soft pedal. On replacing the brake light switch on account of excessive pedal pressure required to make the brake lights operate, I found that there was air trapped in the old switch. I filled the new switch with brake fluid via a syringe and filled the open base on the T piece, quickly upending the new switch and quickly screwing it in to avoid any loss of fluid. Result, a hard pedal and much better braking, thus confounding my mechanic pal who was convinced there was no more air in the system.

Have you adjusted the rear brakes? if the adjusters are backed off you get very similar symptoms to air in the system.

... no ore air could be bled out of the system
...
there was no more air in the system.

I give your mechanic a bit of credit. I expect his version was the first and the second is your interpretation of what he said and meant? There is a subtle difference.