Leak in the brake booster line.

[brewey]

Evening ladies and gents. I started the car this morning and the revs at idle we're bouncing all over the shop. It runs fine when moving and pulls strong through all the gears although when the clutch is dipped it does bounce a bit. But when stood still there is some bouncing. It's way more noticeable when cold.

Now when I got home I was having a poke around and noticed that at the 90 degree bend in the brake booster just before it goes into the bulkhead (under the airbox) appears to not be connected flush. Now my question is should the two pieces sit flush or are they purposely slightly gapped. When I tried pushing them together there was a noticeable hiss of air as if it were a release valve.

Sorry for the length of the post but it's annoying! Especially with a poly bushed dogbone.

[james2]

It might be lose, it should not hiss by touching it.

[Wayne]

Look for a s/h replacement, stupid money new I priced one for the Octavia once and it was the same as the Golf and over £140 and that was a few years back.

Make sure you get the part number from it as they have changed many times over the years, they were once one piece then a multi piece set up.

[brewey]

Can you replace with silicone hose as tbf that would be much easier.

[Wayne]

Can you replace with silicone hose as tbf that would be much easier.

Nope as it needs to be a solid plastic pipe or it will suck inwards and you will lose servo etc.

[brewey]

Hmm. That sucks. Although I'm not sure that a vac leak is the problem anymore as I gave her a good going over yesterday and noticed that the boost gauge doesn't move up and down with the revs (not noticeably anyway). I decided to give the car a service with new oil and plugs etc the car is improved from doing this but the revs are still dipping when started. Next weekend I'll whip the TB off again and clean it, as it's been a while.

 Then I'll be at a loss.

I also wondered about the clutch switch having something to do with it as it happens when there is no clutch engaged.

[brewey]

I got my scanner through yesterday (thanks Nav) and gave it a quick scan this afternoon, it has two fault code stored for the maf and n75 so that's my first port of call.

I had a look under the manifold today and I think I'm going to replace the vac line to the FPR. Most of it is already silicone for the boost gauge, but there is a section of original pipe.