300Tdi Crankcase Ventilation Valve

Oil is leaking from the point where the valve goes into the rocker cover. I've taken it off to clean it and the rubber O-Ring seemed flat. Will any O-ring of the right size do as a replacement (does it have to be oil resistant?), and also, is there supposed to be a gasket anywhere? If there's a specific O-Ring, does anyone have a part number?

Cheers,
Lewys

no gasket just an o ring but needs to be suitable for engine temperature...

Hello,

Can I just remove the small crankcase ventilation suction hose from the turbo air inlet and block it off (both ends)?

In effect the crankcase and the rockercover would be connected directly together via the crankcase ventilation valve.
Would this cause a pressure problem? or absolutly must I put a waste-can or oil-separator on the end of the small hose from the crankcase ventilation valve?

I replaced the whole valve.

I've read a fair bit more since, and it seems the norm is to simply fit a catch can to the end of the hose.

Jason F said:

Hello,

Can I just remove the small crankcase ventilation suction hose from the turbo air inlet and block it off (both ends)?

In effect the crankcase and the rocker cover would be connected directly together via the crankcase ventilation valve.
Would this cause a pressure problem? or absolutely must I put a waste-can or oil-separator on the end of the small hose from the crankcase ventilation valve?

Click to expand...

Hi Jason, just for your info, the device (black plastic cylinder) attaching to the side of the rocker cover is in fact called a cyclone filter and there to release any pressure in the rocker cover, not the crank case.

It works on the basis of separately oil and fumes. Fumes go to inlet tract and oil goes back to the sump.

I eneded up disconnecting the feed from the cyclone breather to inlet hose, and put an empty coke can on the outlet from the breather lol. Worked a treat.
Only just taken it off for the MOT today, thought the tester might think thats really taking the ****! (the fail ist was long enough anyway )
Alisport to a replacement breather on fleebay about £85 but Im just going to get some big bore pipe, block it off on both ends, put a spigot for the hose and a hole in the top for the air to get out.

Hello, I've had a think about this.

I installed an atmospheric ventilated catch-can on the end of the cyclone filter but I think this may be a wrong move. With the factory set up, the air oil vapour was being sucked out of the rocker cover (neg pressure) via the engine air inlet and by positive pressure in the rocker cover. A cyclonic filter works best the faster the air flow (i.e. more centrifugal force to throw out the oil particles against the outer wall of the cylinder where they condense and fall downwards to the bottom drain hole). Now that the rocker cover is only being vented to atmosphere with no negative suction from the engine air inlet the speed of air flow through the cyclone filter is nowhere near as high (as its only the rocker cover pressure that pushes out a small amount of air). This means that the filter cannot separate as much oil as it did before, due to the low air speed. I have found this to be the case. This design is a radical change potentially allowing pressure to increase in the rocker cover at high revs ?. I am running the old girl hard with air inlet at up to 1.5Bar measured on the manifold. I am concerned that the pressure in the rocker cover could cause a problem? Does anyone know if this is ever likely. Seems to me that the most efficient design is simply to leave the factory setup as is, but add another cyclone filter in series to try and remove any oil that gets past the factory fitted version. This way the air velocity remains essentially the same, but less oil into the intercooler.