Technical Rocker cover breather pipe (leak)

[dtimmins1985]

Morning everyone,

So guys, i changed two coils a few weeks back as i had a missfire on cyl 2 and 4, it drove better than ever afterwards and had since started acting a bit rough on idle and sometimes hesitating again.

So on friday i changed the other two coils and shes running sweet again.

Also had manicat replaced under warranty as mine (6months old) had cracked on the down pipe due to the gearbox bracket restricting its movement and vibrating on the down pipe to flexi (well we think that was the cause)

Now when changing my coils i noticed the breather pipe on the rocker (cam) cover is leaking onto the cam cover.

The pipe has a split at the top where it connects to the air intake, but has been tightened with a jubilee so should be ok.

Why is this leaking, its only a tiny leak but worrying me, i cleaned the right hand side of my cam cover the other week but there is fresh oil on it again... I want to stop this from happening, can anyone help?

 

[shanehane]

Just replace the pipe. These types of rubber pipes break down because they are low pressure so just made with cheap flexible rubber.

If the head pressure is leaking entirely out of this pipe it can ruin your idle because of the way the engines are tuned so best to simply replace it

 

[Artermis]

That could well be linked to your idle issue as you're leaking metered air.


The air intake and breather pipe setup is all linked together. I'm not sure what engine you're running so the physical locations may vary however the technical aspect should remain broadly the same across everything.


So your air intake has an airbox, airflow meter, throttle body (valve) and intake manifold.


All this is connected as a circuit to your crank case and breather setup. Engines being the big compressors that they are inevitably move some air around which mean you're going to have some air being drawn in to the crank / block and some being forced out.


You should find that somewhere after your airflow meter (MAF) that there is a breather pipe that is to supply fresh air to the engine casing. Being this is post MAF this is metered air and the engine is using this in it's calculations to run the AFR (air-fuel ratio).


There will be a second pipe somewhere too that vents the engine case into the manifold - this will be venting into the manifold somewhere after the throttle body.


This is technically a PCV setup - positive crank ventilation. There may well be a valve in this vent line to the manifold called a PCV valve, some engines (generally speaking - don't know about Fiat) have a restrictor in place rather than a physical valve.


These valves are to prevent the engine just hoovering up all the oil etc out the engine by vacuuming too hard on the engine casing.


An engine is at max vac at idle. This is because engines always need air to run yet at idle the throttle body is closed, meaning the engine is trying really hard for it's air - so it vacs through the engine casing vent - remember this is metered air.


When you press throttle, throttle body opens and air can flow much more easily through the big throttle body and the vac drops way down as air rushes in.


So at idle, when she is vacing hard any air leak is going to draw in unmetered air and mess up the AFR.


There is also the second potential issue that if you're crank case is hitting quite high positive pressure then the ventilation setup might not be functioning correctly.


Remember back in the good old days everyone used to fit little K&N style filters on their casing breathers - nice idea on older engines as they were designed to vent to atmosphere. venting to atmosphere is now illegal as the air contained oil vapor fumes and alike that are considered harmful. So now we have the more complex sealed systems.

 

[dtimmins1985]

Ahh that makes total sense bud.
Ill get the pipe replaced tomorrow, does anyone have the fiat part no for this pipe? Its a 1.2 16v active 2003

 

[dtimmins1985]

Also remember my Nissan k&n setup and the small breather filter on the rocker cover i had to fit

 

[Davren]

Ill get the pipe replaced tomorrow, does anyone have the fiat part no for this pipe? Its a 1.2 16v active 2003

This is for the 1.2 16v engine. Item 5 perhaps?
.

 

[dtimmins1985]

Thats it bid, thanks, will price it up today

 

[dtimmins1985]

Just called clemo fiat, that part is 38 quid inc vat, wtf!! For a rubber tube less than 10inch long, joke!!! Gonna have to go hunting now...

 

[Davren]

Just called clemo fiat, that part is 38 quid inc vat, wtf!! For a rubber tube less than 10inch long, joke!!! Gonna have to go hunting now...

If you're looking for a secondhand one, the same part number pipe is used on 2003 - 2010, 1.4 16v Pandas.
.

 

[dtimmins1985]

Excellent thankyou Davren.
One last thing - i checked samco for a hose kit, they have them for the 1.2 engine for £28 ish - a full hose kit, does that sound right?

If so, might aswell just buy the hose kit and replace the lot if its only around 30 bob, will look nice too

 

[Davren]

Are you looking for the correct pipe? I can only see turbo hoses on the Samco site.
.

 

[dtimmins1985]

Are you looking for the correct pipe? I can only see turbo hoses on the Samco site.
.

I didnt have a good old look, from a quick search they listed the 1.2 hose kit from 28.odd