TR5/TR250 Brake Booster

[glemon]

I replaced the old (presumably original) brake booster on my TR250 a few weeks ago as I noticed in addition to making a sucking sound when I pushed on the brakes, it also was accompanied by about a 400 rpm increase in the idle speed, brakes on vs. off.

I replaced the master cylinder last year, and it does not appear to be leaking, but I still get a pretty noticeable sucking air sound when I step on the brakes (with a slight variation in idle speed but settle back to normal after a brief blip when brakes are pressed).

I haven't had too many British cars with a servo, is this normal? Or should I try to exchange the unit while still reasonably new? Or?

 

[poolboy]

No matter the car vacuum assisted servos all work the same...Air does enter the servo from the cockpit side, thru a small filter when you depress the brake pedal..That's where my whistling sound was coming from, but it ended up being just debris....kind of like the reed on clarinet, but it didn't affect the idle.
Click the 'red arrow' in this animation:
https://auto.howstuffworks.com/auto-parts/brakes/brake-types/power-brake2.htm

 

[glemon]

Thank you, I did know they all worked the same, I did not know sucking outside air was part of the process in addition to the engine vacuum. Still think it is making too much noise. Will investigate further.