VACUUM PUMP for Power Brakes

LAND ROVER DEFENDER 300TDi

LR Part No ERR3539   made by WABCO

• The pump in bits...
• makeshift repair
• SYMPTOMS OBSERVED
• LATER ON

Disassembled unit (Oh? They are sealed and not repairable?). Shown on right fender of 300TDi during investigation.

A fifth hole is visible in the photo above.
I suspect that THIS is also a valve - I can't remember now. Nor can I work out where is connects!

Ooops.

Vacuum is created on each side of the diaphragm and plastic one-way valve capsules ensure air is sucked from the power brake booster back into each side of the diaphragm cylinder and through into the engine down past the return spring. There are two valves on each side of the diaphragm, one to allow into the cylinder from the brake booster, and one to allow air out of the cylinder on the opposite stroke of the diaphragm.

In the unit removed from the Whitlock Defender (UCU512) the two valves on the underside of the diaphragm had come out of their setting.

One was crushed to pieces (even the spring was a flattened twisted mess) with plastic and metal circlip/springclip pieces embedded in the underside edge of the diaphragm rubber seal.

The other was partly out of the socket and the spring and rubber valve pieces were in the "tunnel".
 
 
 
 

makeshift repair

• refitted the reassemblable valve (salvaged parts), and relocated the accessible valve from the cover plate (above, with circlip) to the underside openings.
• The diaphragm was refitted into the body and the spring refitted with the colletts- (similar to engine cylinder valve stem colletts)
• One valve was left in the cover plate (on the "up" stroke or clearing stroke) [because it was not accessible!] and the cover replaced and fixed with large aluminium poprivetts.
• Unit refitted to engine and pipe connected.

So we have 3 of 4 one-way valves actually in this unit. (or at least ONE LESS than we should have!)
Power assistance for braking appears to exist now, but the test drive is tomorrow....

TOMORROW CAME and the brakes are good. Wow! Takes some getting used to it again to have power brakes, huh?

SYMPTOMS OBSERVED.

Pedal action is very hard, requiring lots of pedal pressure. The pedal has very little movement, as if something is jamming behind it (sort of like less than 1cm travel!)
This means we have had to learn to push REALLY hard on the brake pedal.

When the engine was started, whilst holding the foot on the brake, the pedal did NOT move as it does if the pump is functioning properly.

Braking from speed is still good, but holding the vehicle stationary at traffic lights etc, and not bumping poles in carparks (low speed manoeuvres) is VERY difficult.   [ooops]

LATER ON

• Fit: At least one more one-way valve must be fitted
• Replace: one of the 3 existing circlips.
• Replace: Rubber diaphragm seal if possible.
• Get: thinner arms   :-)

PO Box 51, EASTWOOD NSW 2122, AUSTRALIA

phone  (02) 9638 1142               fax : (02) 9638 1131
international 61 2 9638 1142   international 61 2 9638 1131

LRMan@whitlock.com.au     website    www.whitlock.com.au

Workshop Manual  (Publication Part No LDAWMENBW Volume 2 of 2)
Section 70. Page 28 (ADD: JUNE 94)

Haynes Manual - LAND ROVER 90, 110 & DEFENDER
Pages 10.17 & 10.18



 

Rubber Seal