420g Brake Servo

I have a slight hissing coming from around the brake pedal area when engine is running. It stops when I put slight pressure on the foot on brake, so after reading the service manual I’m guessing there is a vacuum leak in the servo on the back part of the diaphragms. The servo is a Dunlop with a split clamp so I presume it can be taken apart. Has anyone rebuilt one of these and if so is there a service kit you can get??
I have a feeling it the lip seal on the back part that’s leaking …



there were service kits but i think most people upgrade to an xj unit as it is superior

I do not know whether there is presently a major overhaul kit for a Dunlop 90 booster.

At one time, there was not, which is why many MKX have the later Girling Supervac 100 fitted

I would contact SNG Barrats or a specialist brake supplier in your country

I have seen a photo of a very expensive restored car with one, so perhaps you will be lucky

Thanks guys.
I had a good search already with no luck. Next step I’ll pull the unit out and have a look inside. If it’s the seal I suspect then might be possible to get off a seal supplier… There is a company in nz who rebuilt boosters so will also talk to them…thanks for the replying

the above is the 3.8 kit 61-64…not the 4.2 kit 65-67…the OP needs that one