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cathastrophic brake failure

The first step is to put it on your own schedule. Check electric connection for corrosion, running time from zero to full pressure, and excessive noise.
 
UHU, Bob, great write ups and pics. It is possible to have the unit repaired, but I'm more inclined to replace it with new, simply because its the brakes.

In terms of preventative, yes I think at a minimum the unit needs to be inspected on a regular basis. A 100k miles is not that high a milage to expect somthing like this to fail (in my case is was 225k miles) - on the other hand you also need to factor in the age of the vehicles.

There are safety implications with the motor failing as it does. You wonder whether this should be reason for a recall...
 
Ours just did the exact same thing Rein last night with the missus driving the youngest to gymnastics :-(

The brakes haven't failed but it sounds imminent...

Have you sourced the replacement yet? £2.5K ffs...

Cheers dawg
Gav
 
As post 6, have a chat with Mike at Robson and Francis. I’ve just spoken to him and it turns out the motor is a fairly standard design. Others are fitted in various forms to power steering, and gearboxes on minis, BMWs, Fords etc. They are rebuilding lots of the motors.
Talk to Mike, he may get you to send a photo but will likely be able to help.
 
Nice one SC - I'm booked in to have the codes investigated on Monday & will go from there :)
 
Pulled into the garage car park this morning to get the ole tub of crap looked at (driving with that bluddy alarm ringing away isn't good for the tinnitus!!!) & the dashboard illuminations disappear & the alarm stops ffs...

I know the garage is pulled out with work & staff shortage so I decided to just go to work in him. No recurrence of any faults.

So, are codes stored on the OBDC (sp.) thingy or will they have disappeared too?

I am obv driving like Miss Daisy with hand hovering over the hand brake!!!

Cheers
 
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The code(s) should be stored. iirc there's a power connection on the side of the pump under a rubber boot that can corrode and stop the pump getting up to pressure.
 
Wow
UHU, Bob, great write ups and pics. It is possible to have the unit repaired, but I'm more inclined to replace it with new, simply because its the brakes.

In terms of preventative, yes I think at a minimum the unit needs to be inspected on a regular basis. A 100k miles is not that high a milage to expect somthing like this to fail (in my case is was 225k miles) - on the other hand you also need to factor in the age of the vehicles.

There are safety implications with the motor failing as it does. You wonder whether this should be reason for a recall...

Wow … What's wrong with the concept of "fail to safe" ?

If you have a part number and keen to replace with new, let me know the number and I'll see if Toyota Qatar don't have it as one of their amazing bargains. I fly into the UK 1st week in July.
 
The code(s) should be stored. iirc there's a power connection on the side of the pump under a rubber boot that can corrode and stop the pump getting up to pressure.

Thanks Jon, I'll get it into them when they are less busy for a look over. He's driving as he ever did so I'm wondering if there was a bit of water got into it & caused a gremlin...
 
Been away for a few weeks and hadnt updated this ... The master cylinder was replaced with a new unit from Dubai. Cost of the unit was just short of £2k, so an expensive replacement but one that should give peace of mind. The brakes feel pretty good and solid - just like new :)
 
Good to hear you're running well again Reinhard.. it's about the same expenditure to buy new gearbox parts for a hj60... shocking for both application's but need's must and back on the road safely!:thumbup:
 
Does the motor or pump give any signs of imminent failure e.g noise etc ? I'm thinking i should check mine..
 
When you turn the key the motor will start pressurising the system. Should be a smooth buzzzz and no squealing, grinding, etc.
Before turning the key press the brake pedal a few times until it drops. Then turn the key. The benchmark is it to finish buzzing in 30 (+/-) seconds. Might pause for a moment midway, that's ok.

That is sourced from ih8mud and seems to be true for 100s in good working order and not in ones with brake system problems.
 
Thats a really helpful thread UHU, I've looked on the Toyota parts fiche and can't find any numbers for the brake master cylinder seal kit can you tell me where you got yours please ?
 
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04493-60330 - piston kit, brake master.
From dealer? or Amayama? or PartSouq? maybe.
 
Hi everyone,

If this should be in a separate post please let me know, figured it was good to keep similar info together in one thread but happy to move.

Just had the brake booster motor die on the driveway at 190k miles a week before it's MOT.
The least worst place to fail in fairness!

No real warning, pump-on cycle time was well under 30s, only evidence of potential problem was the external corrosion on the casing and the age/mileage (2002/+190k miles).
It's been on the list for refurbishment after a lot of other work... arm twisted now...
Please check yours!

Techstream codes:
C1252 - hydro-booster pump motor
C1256 - accumulator low pressure

IMG_20210822_140732.jpg
IMG_20210822_140740.jpg


IMG_20210822_141323.jpg
IMG_20210822_140751.jpg


On inspection:

Bad bits
- commutator rings worn
- brushes worn
- quite a lot of carbon and rust inside the casing (a good teaspoon full)
- armature enamel appears to have been abraded off
- internal case corrosion
- heavy external case corrosion
- multi-layered gasket heavily corroded, delaminating
- aluminium motor, pump faces corroded
- vent port mostly blocked with powedery corrosion on pump face

Good bits
- braided copper cables to brushes ok
- external electrical cables and screws not corroded at all

It's off to Robson and Francis rewinds tomorrow.

I'm trying to find out (from those who've been through this) what did you do when reassembling as there is a gasket (se below) between the motor and the pump face which is in poor condition.
FIPG? Generic gasket material cut to size? New part available from somewhere?

IMG_20210823_121200.jpg
IMG_20210822_141329.jpg


It doesn't appear to be a part which is available separately from the motor/pump assembly (as below)

1629716195807.png


Any help greatly appreciated.

Also, is it adviseable at this mileage to change out the piston + seals regardless as per uHu's post #37?

Kind Regards,

Graham
 
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