brake booster full of oil

[rob4wd]

hi all,

had the vacuum warning light come on my bj40 and a loss of brake assistance. i put another booster on the truck and decided to open up the faulty one . odd thing is the valve apeared to be working ok in that you could suck but not blow, but obviously oil's been getting in the booster.the one i have replaced it with is deeper so pushes the master into the air filter housing so would like to put the original back on if servicable.
other option is to use a shorter master and do a front disk conversion . i have most of the parts for this but seems a shame as the front axle and drums/shoes are rebuilt and fine (although a pita after offroading and getting mud in).
can i empty this ,twist it back together ,change the valve and call it good or is it toast?
if not it means another knuckle rebuild and discs or relocating the air filter.thoughts and comments welcomed please

 

[vk7ybi]

I think you have a bad vacuum pump on your alternator. I suspect a seal has gone bad letting the lubricating engine oil get into the pump and then your booster.. Theres a vacuum canister in the system somewhere, you'll need to check that too.. Fix the vac pump before replacing other bits otherwise youll have the same problem again..

 

[rob4wd]

I think you have a bad vacuum pump on your alternator. I suspect a seal has gone bad letting the lubricating engine oil get into the pump and then your booster.. Theres a vacuum canister in the system somewhere, you'll need to check that too.. Fix the vac pump before replacing other bits otherwise youll have the same problem again..

thanks -that make sense-looks like i'll have to pull the vac pump and install new seals and then make sure all the vac lines and reservoir are all clear?

 

[vk7ybi]

I dont know a lot about the vac pump, but thats where I'd start. Might be best to ask in he Diesel section of the forum, the Diesel gurus hang out over there..

 

[lostmarbles]

Is it oil or brake fluid in there Rob? (I think brake fluid is far more likely.)

If it is really oil then I suspect your booster diaphragm (and other internal rubber components too) will be damaged because engine oil is harmful to most (if not all) rubber components in braking systems. And that's bad news because AFAIK new diaphragms are unobtainable.

Note that it is quite common for brake fluid to enter a booster when the main seal on the brake master cylinder fails.

Sure ... your diesel does use a vacuum pump to provide the booster-vacuum and the carbon blades within this pump are indeed lubricated/sealed with engine oil. But the non-return valve on your booster (where the hose from the vacuum reservoir connects) should prevent any reverse flow. And I believe there is another non-return valve on your vacuum pump banjo that would have to fail too for any oil to leave the vacuum pump in the wrong direction.

 

[bj40green]

To me it look's like oil because it's pretty black. Is it slippery?
The vacuum cannister/tank/reservoir is under the bottom under the drivers seat.