The CVH standard breather system has a outlet on the lower rear of the
block which is connected via a rubber pipe into one end of the rocker cover.
The other end of the CVH rocker cover goes to the crankcase breather
system (filter, back into the inlet manifold etc).
Initially i duplicated this system on the ZVH with the Zetec block.
As the Zetec block breather hole is behind the turbo i had to blank it
off and drill a new outlet on the rear of the block.
As you know.
Initially i connected the rocker cover outlet directly to a "catch tank"
that i created out of some stainless steel tube with a breather filter
on the top and several levels of steel mesh inside to hopefully collect
the oil.
I say catch tank but the idea was that the oil would drain back down the
breather pipe into the rocker cover and back to the sump.
This didn't work, to much oil seemed to sit in the pipe between the
cover and the tank.
I later modified the tank so it had 2 pipes, one still from the breather
in the rocker cover and the other now went downhill to Y piece in the
pipe between the block and the other end of the rocker cover.
The idea was that the new pipe on the lowest point of the tank now went
almost straight down so oil wouldn't be able to sit in it.
This is better but it still doesn't work, oil still gets blown out of
the catch tank filter after a while under boost.
I think because the crankcase fumes find it just as easy to go up the
drain pipe as they do through the breather pipe so they keep the oil up
in the tank.
Plan 3 is to remove the Y piece from the crankcase to rocker cover pipe
again and this time take the return from the catch tank down into the
sump below the oil level.
That way there can't be any fumes blowing back up that pipe.
I think i'll have to use a solid pipe up until block level as a rubber
pipe splitting there would empty the sump.
I don't feed anything back into the inlet, i blanked off the 2 holes in
the CVH manifold that used to do that.
You should have enough spare oil pressure to feed the turbo without
affecting the main oil pressure.
Jim
On 05/02/2012 15:06, nigelp wrote:
I'm slightly confused by the plumbing here. On your ZVH you drilled
the block to an 18mm hole and put in a separate line which I thought
was the breather going to your catch tank, I also thought the catch
tank had a line from the rocker cover breather. I thought the fumes
went out of the catch tank filter and the excess oil gathered in the
catch tank which had to periodically be drained off. I asume there is
no PCV in these lines. Confusion is that is the hole you drilled out
in the block to drain your catch tank or is the breather and the drain
is a different line? Do you vent any gases into the engine inlet or
plenum?
One thing I did notice on the Garrett web site is that the turbo
return should not be in an area that receives backwash from the
crankshaft. I think but haven't looked that the crankshaft views
directly onto the breather hole. I guess to solve my confusion, could
you please explain your connections to the catch tank Jim. I have
noticed on one web site an alum block to screw directly onto the block
in place of the breather to take the line to the catch tank.
Unfortunately I seem to have found lots of bits of info on this, but
nothing definitive. I am now trying to make the sum of all the parts
make a whole. As is usual with things like this there is also lots of
conflicting information around.
Thanks for the info on the turbo Jim and Hamish. I had always expected
some play for the reasons you mention and when guys say no play I am a
little sceptical, but this did appear excessive and as Hamish
mentioned I am a litle concerned by the flow to the turbo resulting in
an oil pressure drop. I am still to sort out where to take the flow
from as the Black top doesn't seem to have the additional hole you
mentioned in a previous post. It probably will end up coming from the
pressure sender unit hole - a task for next weekend!!
Thanks
Nigel
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