Breathers

[SteveG]

I've seen lately a few people making manifolds for their breather pipes to have just one to raise..

What's wrong with just tapping them into the airbox?

I was told that it would produce a suction effect - but can this really be true with a snorkel providing plenty of air in. I'm sure some snorkels do restrict air flow slightly, but how this would cause a suction effect on breather pipes I'm not sure.

So what's you opinion?

Cheers

Steve

[minivin]

I've seen lately a few people making manifolds for their breather pipes to have just one to raise..

What's wrong with just tapping them into the airbox?

I was told that it would produce a suction effect - but can this really be true with a snorkel providing plenty of air in. I'm sure some snorkels do restrict air flow slightly, but how this would cause a suction effect on breather pipes I'm not sure.

So what's you opinion?

Cheers

Steve

classic motorcycles that are being fitted these days with modern engine breathers work on the principle that a negative pressure in the crankcases will help keep the oil in. Certain people have been using crankcase read valves from Ducati Pantehs fitted into cylinder head inspection caps et cetera to do this same thing and thereby reduce crankcase pressursation.

If you got a leaky gearbox or axles et cetera, may help to solve that problem, just keep an eye on the swivel oils/greases if you think it's REALLY leaky

[Turbocharger]

As you say, the airbox pressure should be negligible. I fitted a vacuum/pressure gauge so I could see the manifold vacuum at high revs under no load, but in fact there's a slight pressure generated from even the raw air passing through the engine and turbine. There shouldn't be any condition when there's less than atmospheric in the airbox, unless you put your hand over the end to test the seals and empty all the oil out of your axles...

[white90]

They are designed to breathe to the atmosphere only

if you put them into the airbox the oils will be drawn up the breathers blocking them

the suction on a diesel is huge, best let them breathe as they are designed.

PS if the main breather from the manifold picture gets blocked all breathers are now defunct.

my reason for keeping them seperate.

[BogMonster]

If you got a leaky gearbox or axles et cetera, may help to solve that problem, just keep an eye on the swivel oils/greases if you think it's REALLY leaky

Note: If you can hear bubbles being sucked into the gear oils then you really do need some new seals

I don't see why the idea shouldn't work; on a later model Td5 some of the breathers (EGR for one and I think on some models, turbo modulator) are routed into the clean air side of the airbox, and that works fine. They used to each have their own little in-line filter but they used to keep blocking up in dusty environments. If it works for the EGR system I don't see why it shouldn't work for anything else, and anyway I doubt the manifold depression on a diesel is that great, because unlike a petrol engine there is no throttle mechanism.

As JB said though, best to disconnect before testing the sealing on the snorkel, diesels probably will run on EP90 but I'd guess there will be a bit of smoke

[white90]

John/Stephen there is no vacum but there is a LARGE amount of suction

SteveG This is a bad idea to route them into the airbox it will suck the oils up the breathers.

anyone with a snorkel just go and stick your hand on the top with the engine running you'll see what I mean.

if you block the snorkel top the engine will collapse all the rubber piping to the intercooler and the large pipe from the airbox.

if you cover the snorkel top with a plastic bag or thick plastic to check the sealing it will probably disappear into the tube.

[simonr]

I agree that there is a large flow of air - but in the air box the pressure difference to atmospheric is very small. It is a vacuum which will suck oil up the pipes - not flow (unless you have a venturi).

Unless your air inlet gets blocked (I once found a dried bird in the snorkel of my 110 - not such a clever place to build a nest!) I think it's highly unlikely that it would suck oil up the tubes.

Having said that - I still have separate breather pipes, figuring that if one blocks / gets submerged - only one expensive bit will be affected.

That manifold looks very bling though!

Si

[will_warne]

John/Stephen there is no vacum but there is a LARGE amount of suction

SteveG This is a bad idea to route them into the airbox it will suck the oils up the breathers.

anyone with a snorkel just go and stick your hand on the top with the engine running you'll see what I mean.

if you block the snorkel top the engine will collapse all the rubber piping to the intercooler and the large pipe from the airbox.

if you cover the snorkel top with a plastic bag or thick plastic to check the sealing it will probably disappear into the tube.

I've nearly lost a road atlas down the snorkel when testing its sealed.

[LandyManLuke]

when i fit my snorkle in the next couple of days, I'll block it and check for leaks, stalling etc.

In the future, i shall probably repeat this test often to check for leaks.

If the breathers are connected to the airbox, everytime you did this test you would be applying full engine suction to your breather - no thanks, i'd much prefer to keep the two seperate.

my opinion.

Luke