Squeal from Master Cylinder when Applying Brakes

So I've had this problem since I bought my 03 taco a couple of years ago. When applying the brake, a high pitched whine was coming from somewhere around my master cylinder. I am assuming it is a vacuum leak? But if you pressed down on the cylinder, the squeal would stop.

I ended up rigging up some wire down through my wheel well and around the metal body of the cylinder to make it stop. Any ideas what the fix for this issue could be?

 

old school technique is when its squeling spray starter fluid where you think the vac leak is if eng accelerates replace the master cyl...other than that id need more info or even look at it.so you think brake booster is leaking? could be..

 

Did you pedal effort increase at all when you noticed the noise? If that is the case I would say the vac booster is the most likely cause and needs replaced.

 

Nope, pedal effort had no increase. I mainly noticed this was when I was at a light or something similar and if I pressed the brake a little bit harder while sitting at the light, it would begin to squeal. The harder I pushed the louder it became.

 

I'd be squealing too it you kept pressing on me harder! Do as lunch box suggests, get a can of starter fluid and give the booster a squirt.

If you have a small propane bottle, that will work as well, but the engine will lug down instead of rev'ing up as with the starter fluid if there's a vacuum leak.

Just don't pull a boner and light the propane first, it may have catastrophic results.