Brake booster issues, oil and pedal travel variations

[ken cheers]

I have 1985 gx diesel cruiser. 210,00 tar road km. I had a booster fail and changed it over from a wreck. The failed booster had a lot of oil in, 400ml aprox and also the clutch booster had some oil. No oil was found in the pipes from the vac pump, no smear even. I cant work this out? maybe the times at full temp, the mist of oil vapours passes into boosters and then liquifies? After this change i noted the pedal often went about 70% down in travel rather than 30% aprox. This is intermittent. I changed the master cylinder as i thought it may be the case, but it still has the intermittent pedal distance travel.
Can somebody tell me what is the cause (brakes work well regardless of pedal travel) of this pedal travel changing?
Why is oil getting into the brake booster. It is not brake oil and could only be engine oil.

thanks, ken

 

[unklwedy]

Where does the vacuum pump draw in air ? Is it near a leaky valve cover gasket ?
One possibility for flakey brake pedal could be the push rod (adjustable) in booster.

 

[mongoose2231]

U know my pedal sinks too towards the bottom slowly after I apply brakes. I haven't looked into it but feels a bit like a vacuum leak. Must check and report

 

[ken cheers]

It appears to come fro a pump at the rear of alternator. i should know more about this car but it has required such little work over 15 years. from the alt, it goes to a cylindrical canister on the passenger firewall. The pedal travel varies. its a guess each time you apply brakes on whether its a 30% travel or a 70% travel. So i cant see it being the rod?
Mongoose, that would occur if you were losing fluid, but i will assume that would soon be obvious. Air in the system will make a spongy pedal. Master cylinder not holding fluid, with leak back occurring?

 

[unklwedy]

What about brake calipers and/or pads that haven't been lubricated in 15 years ? Pads mite ocassionally get stuck a bit further away from rotor.

 

[ken cheers]

Than

What about brake calipers and/or pads that haven't been lubricated in 15 years ? Pads mite ocassionally get stuck a bit further away from rotor.

I changed the pads a year ago for the first time. There is no lub point here on front. But the whole issue identifies that the wheel ends are functioning correct with no change to braking pedal force and there is no binding or heat build up that supports binding. Its just the pedal position achieved when braking that changes randomly. Im advised it is a booster issue? but $350 for a exchange booster seems a little high (plus frieght $50)

 

[ozcrusier]

The alternator vacuum pump is oil lubed and once the vanes get worn and chipped oil can get through into the vacuum tank.

 

[ken cheers]

The alternator vacuum pump is oil lubed and once the vanes get worn and chipped oil can get through into the vacuum tank.

awesome and thankyou. I am planning to replace the recently added 2nd hand booster to a reconditioned one. Ill check if there is oil in it again. although there was no residual oil in the lines and fitting and maybe near half a liter of oil in booster when i took it off a year ago. This whole car has done 220,000 km or 137,000 miles. Spoke to others who have had much more out of this and never any of these issues or booster failures. Maybe its a time issue also as it is now 30 years old. I have no issue with vacuum supply except the last booster lost all vacuum assistance (when in the city towing a loaded trailer and seeing an up coming red light. Handbrakes were my friend)

 

[ozcrusier]

Ken
Oil wont make it past the vacuum tank into the booster unless there's no tank. If you find the vac tank it should have a drain plug for draining.