Thread: Where do you put the catch can?

Originally Posted by AndrewMilne

Thanks, Discorevy, I was indeed missing the fact that when the turbo is working, its boost pressure would reverse the crank-case ventilation flow and pressurize the crank-case, if the rocker cover were connected directly into the intake manifold.
For my further education, why is crank-case pressure not positive when the engine is under load?
Where does the pressure that results in crank-case ventilation actually come from?
Regards, Andrew

OK , the reasons are manifold ( pun intended..........for philipA ) crankcase pressure is still positive under load but less so as the pressure of the higher combustion ( bang) is greater therefore pushing the compression rings harder into the bores providing a better seal, but because this occurs with increasing revs you still have some combustion gases from the power stroke and air from the compression stroke escaping into the crankcase past the rings as well as a small amount from turbo seals etc. The crankcase ventilation valve on the td5 works on the same principal as a petrol engine but it's calibrated differently ( vacuum at idle being one factor) sierrafery replaces them frequently as when they gunk up they allow more of the gases into turbo intake ( not inlet manifold) than normal ,affecting performance.

Originally Posted by Bohica

Can you post a photo or two? I have the rack for a second battery.

You won't get back pressure if catch can is connected to the air inlet.

That sounds right. It should be connected to the air inlet. will send some pictures tomorrow night

Originally Posted by Bohica

You won't get back pressure if catch can is connected to the air inlet.

You will if the internal diameter of the hose is too small

Folks,

where is the 'drain' at the bottom routed?
how is oil 'if any' collected?

Run drain down somewhere where it is accessible from under the vehicle,but out of the way,it should have a valve at the end,drain into suitable container every 5000Km,approximately.
Replace strainer in can every 30000Km,with anoher genuine one.
This is important,or it can clog up and then increase crank case pressures if the relief valve in the can isn't working correctly.

Originally Posted by Parker

Folks,

where is the 'drain' at the bottom routed?
how is oil 'if any' collected?

Looked to route it down but then just decided to loop it and cable tie it... The provent has a ridiculous long drain tube really.

20211204_135912.jpg

Thanks for that, it makes sense.

BUT I should have asked: how do you know when to drain, would you check by opening the top?

Thanks

Originally Posted by Parker

Thanks for that, it makes sense.

BUT I should have asked: how do you know when to drain, would you check by opening the top?

Thanks

Drain it periodically - or watch for the oil level to rise in the hose and drain it before the filter drowns. The hose is there to hold the captured oil and to allow the filter to drain and the canister to breathe freely. For it all to work the hose needs to be straight downward run so gravity can do its job.
I collect around 20ml per 1000kms …..