Breather pipes and oil vapor

[afennell]

I want to stop the oil vapor being sucked up into my nice new turbo. There are 2 breather pipes going into the induction kit, one feeding the catch can from the cam cover.

Where does the other one go, it’s a little difficult to follow.
Is it okay to have these venting to the atmosphere via a little filter or do they need the vacuum from the induction?

[jimGTS]

Vacuum helps, but most just vent it. The catch can one.
I used to vent the catch can with a filter, but it gets oily quickly and becomes restrictive. (This was on my old car)
Current one I just vent via the pipe that goes into the intake (I point it down)

The other pipe is the idle line to the throttle body.
You need this.
However you can fit a filter by the throttle body (just follow it around), and in turn you don't need the other pipe in the intake.

[shinny]

The standard induction has three pipes going into it:
1) The largest is the BOV recirc
2) The next largest is the crank case breather that connects to teh stock catch can
3) The smallest is the idle control line

You want to block line 2, which IIRC is 19mm ID. Then place a micro-filter on the catch can

[fred130111]

I have to agree with that, my oil breather lasted about 6 months before I discovered it had got sludgy and blocked! Apparently this can cause the rocker cover gasket to start leaking.

[Mr Bognor]

why do people vent this pipe .

What is the gain to be had .

Alan

I have to agree with that, my oil breather lasted about 6 months before I discovered it had got sludgy and blocked! Apparently this can cause the rocker cover gasket to start leaking.

[shinny]

I have to agree with that, my oil breather lasted about 6 months before I discovered it had got sludgy and blocked! Apparently this can cause the rocker cover gasket to start leaking.

Depends which engine you've got. The rev3 has the catch can with a return to the sump, making the breather much less likely to block up.

I wouldn't stick a vent on a rev2 turbo engine without also using a catch can, that'll probably get messy

why do people vent this pipe .

What is the gain to be had .

Exactly as the OP stated... to stop oil going all over the inside of the induction tract

[fingers99]

The blow by gases won't hurt the turbo, but will coat the innards of the intercooler/charge cooler and reduce its efficiency. This is a bad thing.

Any breather venting to atmosphere (rather than back to the inlet manifold) is (although a lot of folk get away with it) an MOT fail.

So, a decent catch tank.

In my experience, turbo engines in rude health don't vent a lot of oil, indeed, most of the contents of a catch tank, especially in winter and shortish runs, will be water.

Flame trap recommended, just in case.

[Peter Gidden]

Any breather venting to atmosphere is an MOT fail.

Can you post a link to the relevant part of the tester's manual please.

http://www.motinfo.gov.uk/htdocs/m4i00000001.htm

[fingers99]

Any breather venting to atmosphere is an MOT fail.

Can you post a link to the relevant part of the tester's manual please.

http://www.motinfo.gov.uk/htdocs/m4i00000001.htm

You may even be right -- if you're asserting I'm wrong. I'm waiting for the searchable version to come back with a fixed search engine, and I'll ask my MOT man next week assuming he's still talking to me.

To my mind, though, blow by gasses by definition contain exhaust gasses (otherwise they wouldn't be blow by gasses, eh?). You'd be barking mad to pump those into the engine bay.

[Peter Gidden]

Any breather venting to atmosphere is an MOT fail.

Can you post a link to the relevant part of the tester's manual please.

http://www.motinfo.gov.uk/htdocs/m4i00000001.htm

You may even be right -- if you're asserting I'm wrong. I'm waiting for the searchable version to come back with a fixed search engine, and I'll ask my MOT man next week assuming he's still talking to me.

To my mind, though, blow by gasses by definition contain exhaust gasses (otherwise they wouldn't be blow by gasses, eh?). You'd be barking mad to pump those into the engine bay.

Fortunately, your mind and difinition is not important. It's the MOT Tester's Manual that matters.

Venting to atmosphere is not and never has ben a reason for failure to issue an MOT Certificate.

[fingers99]

One day your ego will betray you. I hope I'm around to see it.

But I will check, and I will ask my MOT man.

[Peter Gidden]

One day your ego will betray you. I hope I'm around to see it.

But I will check, and I will ask my MOT man.

Ego has nothing to do with it. Knowledge is what matters.

Posting seemingly authoritive statements which are in fact total b0ll0x does not assist other forum members.

Assuming your MOT man uses the same Tester's Manual as VOSA are kind enough to publish online, and which I provided you a link to, then he will agree with me.

[shinny]

One day your ego will betray you. I hope I'm around to see it.

But I will check, and I will ask my MOT man.

Seriously... Peter asks you to prove something you've said and you have a go at his ego rather than backing up your statement with a section of the manual?

Peter is entirely right in that it's the letter of what's in the manual that matters, not what you "think". TBH, even asking the opinion of an MOT "guy" isn't exactly proof. Ask anyone who's had to explain their way through the '94 import / decat loophole to your common or garden MOT tester knows testers don't know every single regulation in the manual and make all kinds of assumptions because they spend most of their time on "normal" cars.

[shinny]

I'm waiting for the searchable version to come back with a fixed search engine

Why not use google? It can very easily search individual sites you know!

http://lmgtfy.com/?q=site%3Amotinfo.gov.uk+breather

Nope... no mention of "breather" anywhere on the government's MOT site, which includes the full manual. In fact, if you cut the search to "breath" the only result is a spelling error of "breadth":

http://www.motinfo.gov.uk/htdocs/m4s09000401.htm

Also, there is no mention of the terms "vent" or "crank", and the only reference to "ventilation" is regarding the testing location:

http://www.motinfo.gov.uk/htdocs/tgs0d000502.htm

[ashley]

Interestingly- no mention of venting to atmos in the IVA regulations either

[fingers99]

I downloaded it, searched the .pdf, as I promised, and can find nothing. I'll see what the MOT man says --

It looks like I made a factual error. Mea culpa. I'm quite happy to admit when I'm wrong.

As for the wisdom of venting into the engine bay, well........

I actually find I was refering to the wrong document (was sure it was there somewhere!).

The Road Vehicles (Construction and Use) Regulations1986:

54.—(1) Everyvehicle propelled by an internal combustion engine shall be fitted with anexhaust
system including a silencer and the exhaust gases from the engineshall not escape into the atmosphere
without first passing through the silencer.

And more pointedly:

3 Vehicles first used on or after 1st January 1972 and propelled by a spark ignition engine other than a 2-stroke engine.

The engine shall be equipped with means sufficient to ensure that, while the engine is running, any vapours or gases in the engine crank case, or in anyother part of the engine to which vapours or gases may pass from that case, are prevented, so far as is reasonably practicable, from escaping into the atmosphere otherwise than through the
combustion chamber of the engine.

Can be downloaded from www.persona.uk.com/ashton/Core_docs/New/D43.pdf but doesn't seem to contain later amendments.

Of course, the Construction and Use regulations, not the MOT regs, not the SVA or IVA regs, define the legality of a road vehicle.

I rest my case.

[ashley]

"as far as is reasonably practical" does it for me

[fingers99]

"as far as is reasonably practical" does it for me

There's some wiggle room there, but it's difficult to argue that you've taken the "reasonably practical" step of by passing the system Toyota fitted as stock!

[ashley]

"as far as is reasonably practical" does it for me

There's some wiggle room there, but it's difficult to argue that you've taken the "reasonably practical" step of by passing the system Toyota fitted as stock!

In my judgement I find it neither reasonable, nor practical, that I should pass oily gasses into my nice clean compressor wheel

[ashley]

All joking aside, and being purely pragmatic, I've never been pulled up on any MOT for venting crankcase gases (via a catch can) to atmosphere (on 3 or 4 cars so far)...it may well be against the spirit of the text you've linked, but in practical terms you'd have to be unlucky to get pulled up on it.

On my old vauxhall I even used the old coke bottle mod instead of a catch can, got some funny looks on the test, but no fail