Jump to content

Thor breather setup


Recommended Posts

Hi All

Trying to sort the breather setup out on my 4.6 with a Thor top end, can someone help confirm the following:


Right hand (drivers) bank rocker breather has a spiral oil separator in the rocker 'spout'. 

Breather pipe on RHS bank goes to vacuum source after the throttle body. There's no additional PCV / restrictor in the hose.

Breather pipe on the LHS bank goes straight from rocker cover to inlet pre-throttle body. Again no restrictor / PCV?

Just trying to figure it all out - from my research air is drawn in through the LHS rocker, round the engine and out of the RHS, pulled by vacuum. However normally there's a PCV valve somewhere to stop it drawing air through the breathers all of the time, yet LR didn't seem to fit one from what I can see...

Link to comment
Share on other sites

Hmm - OK - the inlet on mine was originally on a 3.5 with open breathers, so where the 4.6 breather would normally connect to has been repurposed for the brake vac hose.... Typical LR, nothing is as it was from the factory :D


It looks like the original breather -> manifold fitting is ERR6880, so you are saying that has a 4mm ID restrictor in it?



Link to comment
Share on other sites

Yes, probably : D

The earlier system was very similar, but ran the 4mm restrictor inside an unequal plastic T-piece. 


I am sure there is a diagram somewhere, but one end goes to before throttle body, the other to one of the rocker breathers, and the other, smaller one with restrictor to the plenum. If you have this T from the earlier setup, then you could use it?

Link to comment
Share on other sites

Found a description of the factory setup:


It doesn't seem to mention anything about a restrictor, and there's varying conflicting reports as to if it's needed! I probably have a spare PCV from another car kicking about somewhere, I suppose I could plumb that in if needed...

Link to comment
Share on other sites

That last link has the arrangement.  On the drivers side of the inlet crossover pipe - there are three ports one for the brakes, one for crankcase ventilation and a small vacuum port.  The crankcase port connects to the top of the rocker cover and sucks the fumes out of the engine.  In the pipe at the rocker cover end is this small restrictor - it slows the flow and catches the mist allowing the oil to drop back into the rocker cover.

On the passenger side, a pipe goes from the rocker cover to the throttle body, and connects just before the butterfly on the airfilter side.  Basically the manifold suction on the drivers side is much greater than the inlet side and it sucks air through the engine.


Edited by garrycol
Link to comment
Share on other sites

Thanks - I'll need to have a proper check of mine, it looks like there's a metal restrictor at the bottom of the rocker spout that has the spiral in:


I plumbed mine in yesterday as per the manual and developed a really bad pick up stumble from idle, so not sure if the slight air bleed round the system is throwing it and I need to reset idle / idle enrichment or if something still isn't quite right...

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy