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Discussion Starter · #1 ·
Got a low oil warning today. Was pretty low on the dipstick. Pulled off engine cover and oil trap hose got brittle and snapped off. Bought some new 1/2” oil cooler hose and cut to fit. I took off the oil cap at idle and now it’s under a pretty firm vacuum. Is that too much? Is the trap diaphragm shot perhaps? It hisses pretty hard when removing. I took a video but can’t see a way to post it on mobile.

2014 XC60 T6
 

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You will want the inner diameter of the hose the same as OEM. Same with all other vacuum lines.

Not sure about the diaphragm, perhaps there is a way to test it. This topic has likely been hashed over before many times. Have you tried searching the forums for any other info? Or YouTube?
 

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That cover has an integrated crankcase pressure regulator with a diaphragm. The diaphragm cracks and it lets the manifold vacuum on one side go to the passage back to cylinder head and it will have noticeable vacuum inside engine. The valve and diaphragm is not serviced separately so the whole black cover is replaced. The hose doesn't go to vacuum on the T6 6 cylinder, it is connected to the air filter to turbo inlet pipe where crankcase vapors will go through turbo to intake manifold. The vacuum source is a passage from cylinder head on intake side that leads to the top of head and to where the breather cover fits.
 

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Discussion Starter · #4 ·
I bought a new oil trap from FCP just in case. Installing it this weekend. So far there hasn't been any noticeable issues as it is. The rubber hose I replaced does lead to the inlet of the turbo, but that should always be under vacuum anyway.
 

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Vacuum if you consider .05 inch at idle and maybe 1 inch at WOT to be that. The only reason there is any pressure below atmospheric is air filter restriction. Numbers will be greater with dirty filter. There is no throttle upstream of that pipe the vent hose goes on. When the intake goes to pressure above idle due to turbocharger pressure there is no possibility for crankcase vapor to go through the passage on back of head around to the intake side where head is drilled lengthwise above intake ports with a 3 mm hole drilled from each intake port into that passage. Then the breather box port which is not controlled by the crankcase pressure regulator diaphragm and valve will allow any crankcase pressure to vent into turbo inlet where there is no pressure. When the diaphragm ruptures on crankcase pressure regulator you can have turbo pressure going into breather box crankcase/internal engine and then blowing through the vent hose to turbo inlet. That can lead to oil loss when the breather box is overwhelmed and the baffles in there to allow oil vapor to condense cease to work well.
 

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