The Stovebolt Site Forums The Shop Area Driveline Engine oil in brake booster

About a week ago my 235 in my truck started to run really rough when i would hold the brake pedal hard to the floor. When i would let up and only apply light to med pressure to the pedal it would smooth back out.

By disconnecting the vac line to the booster i confirmed it was the booster for sure. Im currently running the booster vac line from a T fitting on the manifold that has the other end connected to the PCV valve. I see lots of other people do the exact same thing on all kinds of setups to feed the booster so i think im still safe to do it.

As i tilted the booster to get it out about 1/4 cup of engine oil poured from the vac inlet port. Found out after that my booster one way valve was not restricting air from flowing in, thus every time i would release the brakes the booster would suck in air from the t fitting where the combined PCV port was attached. Im a little concerned as to the amt of fluid that accumulated. It could have been pulling fluid for some time now. I think the rubber in the booster finally gave in and developed a hole in a location where it would fail and full travel.

Possibly my PCV is getting splashed where it is installed in the old breather tube location but it still has the oil baffle installed in the crank area. Its got me a bit concerned that im pulling too much oil mist or something.

Any suggestions?

It may be gasoline or brake fluid. The vacuum hose should go up above the booster & come back down. You will notice all original factory units are like this. GM puts a filter in the line. Brake fluid can get in from a leaking master cyl.

100% its engine oil and not anything else. My booster is under the floor of the cab.

Have you tested the booster check valve.
It allows vacuum into the booster when manifold vacuum is high and traps it in when manifold vacuum is low. It's a one way check valve that allows air to flow in only one direction. If it does not trap the low vacuum state then the higher vacuum in the booster can suck oil in.

Yes and I found it was bad. I know that's why the oil is in the booster. It's easier to suck air in that side rather than the opposite fresh air side thru the boot breather holes and filter.

I'm looking for solutions on possibly other things I can do or add to possibly catch the oil if this happens again.

You could add a vacuum canister into the system, the one I bough from JEGS before had a check valve on its input.
It also help smooth the vacuum level stay low a bit longer.

wolffcub,

What year and size and make Canadian truck?

Does it already have a vacuum tank/canister?

I added a tomato can (vacuum canister) to my 59 for added vacuum for my under floor brake booster. I have an extra one that I took off a 60's model Ford truck for sale.

With a little tinkering, a disposable Propane tank for a Coleman stove or lantern makes an excellent vacuum reservoir. It's much thicker than the "tomato can" reservoir and it can be fitted with a drain petcock to remove any oil it might trap. PM me for a sketch of how to do the modification necessary to convert one.
Jerry

Ford used "Tomato cans" for years, light, work well and look cool. When plumbed correctly there should be no oil in can. Should be a dedicated line to manifold vacuum source. As my buddy says about the old vehicles " When you veer from the stock design you become your own engineer". So true, good luck with it.