420G bleeding brakes

Looking at the photo it appears that the pipes leaving the booster are at 90 deg to vertical? That’s probably going to be hard to bleed air out of.

True, any suggestions?

Never been inside a 420 so no real idea apart from dismounting the booster to see if it can be rotated?

The pipes emerging from the master cyl on a 420G go out parallel, then down.

It is easy enough to bleed the master cylinder in situ, but be careful to avoid fluid getting on the paint

I think you said the pedal goes to the floor, with no braking ?

This is usually failed master cylinder seals…almost certainly if the fluid level in the resevoir isnt dropping due to lost fluid.

How old are the MC seals ?

Hi Tony

Master cylinder has not been serviced for at least 30 years! However, was breaking correctly last Summer. Two years ago, a number of new brake lines were installed, calipers replaced and system flushed.
Fluid in resevoir is not dropping…I had the car turn over for approx. 30 min and held level, cannot see any leaks…
Is it logical to replace the seals on M/C?

THx

B

I would suggest the Master cylinder be removed and assessed by a very experienced brake specialist.

The rubber seals inside become soft, and “bypass”.

if this happens, you have no brakes !

In addition, the bore can become worn or pitted, and (usually) require sleeving in SS

I have had this done on several Jaguars, at a cost of about $A200, including seal kit.

There is very few places that can re -sleeve the stepped master cyl, not sure where you are at.

Thanks Tony,

Well “no brakes” is were I’m at!..Wonder if (due to limited options and time) if I don’t replace the MC?

B

Specialist machinery is needed, (invented & exported by Halray in Australia)

Your pic indicates LHD…I think there is a place in USA called White Hydraulics.

It is better and cheaper to post the item off to them. (ring or check them online)

so called new ones are of suspect quality, and more expensive than sleeving

sleeving lasts a lifetime

seals still need renewing every ~20-30yrs

It’s called White Post Hydraulics and there is also Apple Hydraulics. Google them for details and give them a call.