mk2 golf gti 16v kr. vacuum at block breather

[Monkeymagic]

I have been helping a friend set up their mk2 golf gti 16v.
I have set up countless numbers of these engines.
However when i was setting up the co i pulled the breather pipe that runs from the front of the block to the air box so as to not affect the reading.
However i immediately noticed lots of vacuum from the block at the end of the pipe.it should be venting not creating vacuum.
Anyone got any ideas. The engine pulls well and gave 180 psi on each cylinder. And doesn't use oil.
Anyone got any ideas obviously the pipe does t off the inlet manifold but i have never noticed vacuum on the pipe before.

[martinws]

I cant think of any way a crankcase can be in vacuum. Or am i getting the wrong end of the stick and its another pipe you have removed?

[Rusty]

It's connected to the IM so will give 0.6 Bar vacuum. There's no 1 way valve or anything. Didn't the idle go mad when you did that?

[Monkeymagic]

No neither can i. It is the big main breathes from front of block to the air box. It is td into the inlet manifold with a tiny pipe but i have never seen vacuum here.
I can only think the throttle body isn't closing properly.
However it is touching the throttle position switch and the isv is buzzing.
Confused!

[Monkeymagic]

Yes it messes up the idle and there is no valve you.re right. The correct way of setting up the co is to unplug this from air box then block it off.
I don't think ill disconnect it when i re tweak it.
I have never seen vacuum at this pipe before just lots of oil. That could be because they were tired i guess.

[Rusty]

IIRC, it T's in to the TB on a small bore hose, so is subject to vacuum at idle and partial throttle. Use a hose clamp on that small hose?

Does the breather T in to the lower section of the airbox?

http://www.clubgti.com/showthread.ph...ather-pipe-mod

[Monkeymagic]

It has a small bore t off the inlet mani. And yes it goes to lower half of the air box Eg below the metering head flap.
I could only think the vacuum is direct result of inlet vacuum however i never recall it on any other kr. They normally smoke from the pipe when disconnected.

[Rusty]

My mate's KR had this - 1990.

[Monkeymagic]

Well maybe its just me. I see no other reason to have vacuum coming from the block.
Ill clamp the small bore hose and it should stop the vacuum.
Thanks for the re assurance . Steven.

[Rusty]

From a brief search, not all had this small pipe.

[Monkeymagic]

Maybe that's the difference then. Ill have to check on the next valver i work on. Strange little differences between chassis i guess.

[Sleeper_Avant]

i had loads of issues with my 6a Quattro, turned out to be mostly the full throttle switch and idle switch being shagged and being open circuit.

on my old ford days pulling the oil cap off a CVH would make it cut out too!

i will ask some of my KV guru mates and report back

[Monkeymagic]

I've worked on and built many kr engines. Personally I like 8 valve digifants.. However I have never known such vacuum I struggled to pull the pipe off the air box. It's probably just me.
This one doesn't idle as smooth as normal. That said it s been running off for some time. Now it's set up and done a few miles I'll re tweak it clean out the sticky throttle body and ISV. Thanks for the help so far

[K Simmonds]

I'll have a look at mine in the morning, it's my daily at the moment so I'll pop the breather off when I get to work as the engine will be warm by then.

Will let you know tomorrow evening, I'm curious myself now as I wouldn't expect vacuum on that pipe.

[afterburner]

My ACE also has vacuum on idle when I disconnected the block breather pipe to relocate it...