Low boost. Hard brakes


New member
Oct 6, 2020
2004 bew
Hi all i just recently purchased a 2004 jetta tdi 5spd manual. When i bought the car i was aware of a low boost issue. Being that it has a brand new turbo on it with maybe 30k miles on turbo i figured the problem is somewhere else. I believe the egr pipe is cracked or broken as it sounds like it has a massive exhaust leak under the dash. Anyways was just curious if i could get some more info on places or things to check for the boost issue and the brake issue. Brakes are rock hard to push, pretty much seems like its a issue with the brake booster. Any info helps thanks.


Top Post Dawg
Apr 23, 2010
2007 Seat Alhambra 2L tdi
Check the vacuum lines, could be a leak affecting brakes and boost.

Also common one for the brakes is also often the hard pipe to the booster, often cracks underneath where you can't see them.

If the egr pipe is leaking that might explain low boost too, the turbo needs the exhaust gases to drive the turbine and if it's leaking there it's going to have a big effect on how much exhaust hits the turbine.


Veteran Member
Aug 17, 2008
Reno, sort of...
2001 Jetta TDI
Until you have at least 22" of vacuum, you will have no boost, and no brakes. I would use a cheapo vacuum gauge and test different locations. Disconnect the vacuum line at the vacuum pump, start engine and check vacuum, if less than 22" your vacuum pump is wonky. Otherwise measure vacuum at everything that plugs in and keep checking vacuum. I agree with Seatman, it is very likely that the pipe that attaches to the brake booster has a crack in it.