Please help identify source of engine noise

Its your brake booster pump. Seems louder than it needs to be. I can hear mine sitting in the driver seat. Always comes on when I open the driver's door and will cycle on again after using the brakes a little bit. Its normal. What is not normal is if it cycles on when you are not using the brakes. That is a pretty good indication that there is a leak

I swapped out my master cylinder (accumulator?) and it definitely helped, but I have read of others that had the cycling going on for years.

 

Monitor how often you hear the noise... Once you hear it more than once in a minute its time for a brake booster pump swap.

 

houston, all systems normal

 

I normally hear this sounds whenever I am coming to a stop (using brakes of course) and it goes away as soon as I am fully stopped. Perhaps it's not the same sound, but I definitely do not get it when the vehicle is stationary, unless the car is not on and I open the driver's door.

 

Mine has been cycling at 22 seconds for several years.....

 

So no brake fluid leaks anywhere? Reservoir is good? All pads look okay? No check engine lights? Brakes are working nominal?

If everything is good, I'd not start a "parts canon" just yet but I would do a good brake fluid drain and fill if it hasn't had one in 4-years or more.

 

A brake flush won't fix it for more than a day.