Thread: Fitted pro vent to td5

Originally Posted by onebob

I would leave it in..... it’s a DCV ie a Depression Control Valve, it’s there to regulate the crankcase pressure. It’s normal state is open - unless the engine is breathing really hard, whereby it progressively closes as engine speed increases, thereby limiting depression in the crankcase. Its operation is the reverse of Positive Crankcase Ventilation. Nothing is gained by it’s removal.

Any disadvantage to its removal? Just curious!

Originally Posted by Bohica

Any disadvantage to its removal? Just curious!

Any disadvantage to its removal? .... yes, but how much depends on how hard the engine works. The CDV actually controls pressure/vacuum in crankcase to prevent oil consumption through the intake system via the turbo air inlet. For example when the Td5 takes a sudden deep breath, like what happens when the auto trans kicks down and the revs slam up to 3000+ plus in a nano second, the CDV valve will in that circumstance be pulled and held closed until the revs diminish.

Originally Posted by Kaaaiju

We're do people put the provent when there is an ARB compressor then? As I don't much room any where else?

I bolted mine to the Aux battery shelf’s heat shield...

Originally Posted by onebob

Any disadvantage to its removal? .... yes, but how much depends on how hard the engine works. The CDV actually controls pressure/vacuum in crankcase to prevent oil consumption through the intake system via the turbo air inlet. For example when the Td5 takes a sudden deep breath, like what happens when the auto trans kicks down and the revs slam up to 3000+ plus in a nano second, the CDV valve will in that circumstance be pulled and held closed until the revs diminish.

I’ve had my PROVENT installed 1 week now and I’ve changed my thinking - yes the CDV in a factory configuration is there to prevent the engine consuming (sucking) oil under high inlet vacuum / high engine speed situations, however a PROVENT will perform that function also when installed. I imagine also that a PROVENT would be most efficient operating with a constant air flow, especially under high speed engine conditions / high inlet vacuum situations when blow-by gasses would be at their greatest, however a CDV under these conditions would be pulled closed, and shut off crank case breathing altogether for the duration....
I have replaced my CDV with a brass elbow.

Originally Posted by onebob

I have replaced my CDV with a brass elbow.

Welcome to the club! You’ve reached the same conclusion a group of us had in discussions sometime ago.

Originally Posted by twr7cx

Welcome to the club! You’ve reached the same conclusion a group of us had in discussions sometime ago.

Thank-you .... at first it occurred to me that with the CDR and now a PROVENT inserted into the breather circuit it would slow down the air velocity and volume and perhaps work to pressurise the crankcase instead of maintaining the normal de-pressurised situation. Although the normal state of the CDV is ‘open’ a peek inside of it revealed it’s design created some restriction and that a 3/4” or 19mm elbow would allow more more air / gas to pass. All things considered i thought it best to have ‘full time’ crankcase ventillation. Cheers

I must admit I haven't looked closely but my impression is that the diaphragm in a Provent and others is a pressure relief valve that opens when the filter is blocked.
Regards PhilipA

Originally Posted by PhilipA

I must admit I haven't looked closely but my impression is that the diaphragm in a Provent and others is a pressure relief valve that opens when the filter is blocked.
Regards PhilipA

The valve in discussion (CDV ie crankcase depression valve) is the disc shaped valve at the end of the factory breather pipe that connects onto the rubber bellows pre turbo.