Car had been idling badly. It was rough and occasionaly the revs would drop and jump back up. I only ever noticed a problem at idle.

On inspection i found the vacuum pipe attached to the bottom of the throttle body had 2 splits in it. The general area around the throttle body has a film of oil covering it.

I have a couple of question that maybe somebody could answer.

1. Is the oil normal? (I assume it is not)

2. What problems could the holes in the pipe be causing? I know it affects the Idle.

3. Does anyone have a part number or know where I can get a replacement pipe?

mmm, what model do you have mate??,if the leak is after the throttle butterfly unmetered air will get in causing a rough idle.A small amount of oil is ok but a heavy film isn't,try to trace where the oils coming from.

Its a Mark 5. The engine prefix is AKK.

I think the oil might be related to the split pipe somehow.

ok could be coming from the pipe.Was there any oil in the air filter housing?this comes from the crankcase breather and ends up contaminating the throttle body leading to rough idle and the engine hunting.I cant remember what pipes go into the tb.....

Yes there appeared to be oil in the filter housing. There are 2 pipes/tubes that are attached to the throttle body. One goes to a charcoal canister. The other is the vacuum pipe that has the split in it and it goes to a small plastic part. It is about 2-3 inches in diameter. Not sure what it is.

there should be a few pipes there...

crankcase breather - into airbox

brake servo vacuum - into inlet manifold

EGR - solid pipe into throttle body

Charcoal canister pipe - into throttle body

I have just attached some images of the pipe.

Just been doing some Googling.

I am right in say that this pipe is the vacuum pipe for the brake servo. The brake servo is located beside the throttle body?

So with the split pipe I should have had 2 issues:

1. rough idling

2. less braking efficiency.

There are a number of VW and seat cars that were recalled up to year 2000 with the same problem.

There could be other people on the forum with the same problem that don't realise.

Mine's split a while ago, I just use insulation tape round it for the time being, Will get a new one soonish...also need an engine cover with airbox from a scrappies

I have ordered a new pipe for €12 from the dealer. part should be in next week, on order from Germay.

For the moment I placed a spring inside the pipe and used insulating tape on the outside.

Is that defo part of the servo pipe?? its usually hard plastic with rubber ends and runs from the servo behind the brake master cyl on the drivers side bulkhead to the inlet manifold under the tb.

Nice bodge,has the running improved??

I am not sure what the pipe is for now. It is a rubber pipe about 4 inches long and 1/2 inch in diameter.

The car is idling much better now, I think even gear changes could be smoother.

Here are a couple of images of the pipe with a temporary fix. I have since replaced the pipe. The valve that the pipe connects to had a part number on it. I googled it and found this page for a VW caddy.

parts diagram

The pipe would be number 36 and the valve is 35.

The valve seems to has some oil and slght dirt inside the port that connects to the damaged pipe. Should I replace it or could it be cleaned.