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Bad Master cylinder/brake booster leaking brake fluid into the engine?


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Well, this is definitely something I've never heard of, and I've spent a fair amount of time tinkering with/fixing cars.

I changed all the fluids yesterday (Oh lord, the rear diff and gear oil on my 620....lets just  not talk about it), and used a vacuum bleeder to bleed the brakes. 

All seemed well, until I hit the brakes, and the pedal was surprisingly not hard. 

I started the truck to see if the booster might help...and HOOOOLLY SMOKE!!!!!


Only, it wasn't oil, I could smell brake fluid when the smoke hit me. 

Has this happened to anyone else?

I've got a lot of experience with automotive repair, but nothing older than mid 80's.

If brake fluid is really getting into my engine, I feel like having a hydrophobic fluid inside my engine is going to wreak absolute havock on my seals, and no telling what it could do to the internals...

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You would have to have a failed master also to pass fluid to the rear past the push rod into the booster. Brake fluid isn't going to harm anything, in small amounts. It is safe on rubber or any other synthetic 'rubber' like urethane, neoprene...



Likely spilled brake fluid on the exhaust burning off.

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