Hi.

having a problem with my Octavia 1.9tdi. wee bit of history first:

Noticed a hissing noise when engine running, left it for ages then had unrelated problem with front brakes. brakes all sorted but garage advised me brake servo was faulty (hence the hissing noise). it's a dealer only part at £300 + installation which isn't an easy job.

found a dismantler with a servo with same id code from same model, which offered a 3 month warranty. bought the part, garage agreed to install. supplied part was larger than existing but dismantler advised should do same job. garage fitted part (took 2 days) and i collected it yesterday, expecting my troubles to be over.

driving it back to work, i found the brake pedal to be very stiff and the braking to be very poor. i spoke to the garage and the mechanic told me the replacement servo must be faulty. the dismantler has offered to supply a replacement part but asks that i check the vacuum pump operation first.

so, on to the reason for this post - where is the vacuum pump and how do i check it?

You might already know some of this, but the 1.9TDi produces a very low engine vacumn depression (which is why it is so economical). A side effect of this is that it doesn't produce enough vacumn to run a servo off engine vacumn, but needs a vacumn pump instead. If you can follow the vacumn line from the servo to the nose of the engine, you'll find the vacumn pump.

Anyone else think this looks like another dodgy diagnosis by a "vehicle technician" who has never been properly trained in car mechanics and fault-finding?

Either a dodgy diagnosis or they cocked up fitting the servo and go the master cylinder rod in wrong.

thanks for that Ken, i will try and locate the vacuum pump tomorrow. i guess it will be pretty simple to test its operation.

Lummox, is there any way to check the master cylinder rod without stripping it down?

hi.

just thought everyone should know - when the replacement servo was fitted, the mechanic damaged the pipe from the vacuum pump.

had the pipe replaced, hey presto brakes operational !

big thanks to the dismantler (motors in motion 01909 531537) for the expert advice. thanks to all you guys too for pointing me in the right direction.