Right, the last couple of weeks have been Rnd focused in the shed. None of us have ever fitted a catch can and it's safe to say we have learnt alot about how the CCV system works and it's impact on the engine running.
First job we did was remove the CCV system in its entirety and fitted a rubber bung on the dip stick tube.
To make things easier we reused the original fittings, if you gently cut the plastic tube it reveals a nice barb fitting.
This next image shows the CCV system totally removed, the two red circles are the reused fittings and the line at the bottom is the blanked off dip stick tube. The two fittings at the top is where the catch can sits. So you have gases and oil vapor leaving the rocker cover going through the catch can and the left of vapor entering the inlet manifold to be reburnt... in theory.
This was where the fun begun, the Mk1 catch can setup so to speak had all 3/4" (19mm) pipe this included the connection to the catch can. Also we fitted a non return PCV next to the inlet manifold. I've heard some stories of the sump being emptied back via the ccv system.
The large size pipe makes you stand back and go that looks really odd... and once we started the car it barely wanted to run, you could hear a really loud wooshing noise! it was sucking too much un-metered air in via the manifold. When I squeezed the pipe the engine began to run normally. This lead the re design and dropping everything down to 3/8.
It ran better with the smaller pipe but still not great. I connected Carly and looked at the fuel trims, they were round 10% when they should be below 5% so I was still getting too much air. I fitted another restriction in the Manifold line with a 3mm hole and everything dropped into acceptable figures.
The big question Does it work...... are you using less oil. In short yes it does work but theirs a trade off. Where you've increased the vacuum in the case the rings are pulling harder in the bores in tern creating a more "Laggy / delayed" throttle response. The M54 has never been the most responsive flyby wire setup but it was really bad now. I'm also using less oil and the guys report seeing less puffs of blue smoke.
The long an short of it. The piston rings 'oil scrapper ring' need to be replaced so this will be my next venture. I'll pull the engine out in the near future and replace/gap/hone and give the engine a new lease of life. This is the risk you run buying a second hand engine in a hurry.
Also I've managed to find a 3.0 being broken nearby, finally got my hands on the OEM airbox.
Watch this space
