Squeek Coming From Brake Booster - Sign Of Impending Doom?

[kings1527]

I recently developed a loud squeek from the brake booster area and the overall breakdown is something like this:

-Happened suddenly
-No recent work done
-Brake performance is not affected at all.
-Pedal is nice and firm
-Pedal travel is within normal limits
-Squeek can be intermittent; some days louder, some days not so loud. Possibly affected by temperature. The colder the temp, possibly the louder the squeek.
-Brake master was replaced by me about 5.5 years ago. No known fluid leaks
-Brake calipers and pads replaced by me about 5.5 years ago. No issues. Yay.
-Booster is original to car

I listened to the brake master and the brake booster with a stethoscope while someone pumped the brakes and it's most definitely coming from the booster with spillover sound to the master. Seems like the squeek is getting better with a bit of age; been going on for about a week.

Is this kind a squeek an early sign of an impending booster failure? I know the overall failure rate is very low. Or is this just a case of some part needing lubrication? Seems like that'd be tough to access and not sure how the best way to go about it would be.

Thanks in advance.

[David T]

The squeak could be from the pedal linkage, it just reverberates and gets amplified by the booster. It can be the booster. It can also be the pushrod. You could undo the nuts holding the master cylinder to the booster, move it enough to put a tiny dab of grease on the ball end of the pushrod. If the squeak persists you have to rebuild the booster. The squeak won't affect performance.