PCV System Replaced--Mixed Results

[Astro14]

Clean with kerosene and a .22 caliber bore brush (fits perfectly), or just buy the kit from IPD...

[Carllay]

In light of the all the comments subsequent to my original post after replacing the PCV components on my 2004 XC70, today I took the vehicle to Don Beyer Volvo in Falls Church, Va and requested the PCV system to be checked.

I quote from the notes on the service ticket: "Customer requested the PCV system to be inspected on the boost side. Tech inspected the PCV system. Customer is advised the PCV system is operating as per manufacturers specs; suction at idle and pressure when accelerating."

[bugeye]

Our '04 XC70 has ~ 100k miles with what I believe the original PCV system. With the discussions of crankcase positive pressure and blown cranckcase seals, I have been measuring the crankcase pressure a few times over the past year. I use a low pressure gauge with a tube into the dipstick hole. At idle pressure negative at -0.8" water and in gear (brakes on) at 2000 rpm pressure more negative than -1.0" water. I have never seen a specification for crankcase pressure from Volvo.

[Carllay]

Bugeye,

I was surprised by this response and plan to locate a source to get the actual specifictions.

Thanks

[bugeye]

If anyone can post the Volvo crankcase pressure specification or expectation or actual measurments, much appreciated. I have seen and used the glove test. I have watched the YouTube ball in a tube tests. I think a measured crankcase pressure would be more useful in evaluating the health of the PCV system. Somewhat related, my 2007 Volvo S80 V8 pulls a negative -4" water pressure at idle.

[KJAY]

ALWAYS replace as it cannot be cleaned thoroughly/perfectly
What take a chance for 15 bucks?

My dealer says they don't sell the PTC valve except as part of the fresh air tube, which of course is not $15, and IPD said that they don't sell it either. Where do you purchase it?

[skibo]

Is there some accepted way to measure crank-case pressure? i'm thinking of wrapping a small hose in tape, put5int it in the dip-stick tube and running it to a gauge taped to a wiper. What is the recommended range for this if I can measure it?

[Nightair]

I just went thru all this PCV system fiasco with my 2006 XC70, the original breather tube had been broken where it went through the intake, for how long I am unsure as it was not easily seen. Replacing the breather tube caused the VVTs to get plugged and the CEL to come on with associated rattling. Volvo dealer found the Oil Trap full of crud and the crankcase breather plugged with carbon. The Oil Trap,system was replaced and the crank holes unplugged. The trap requires the intake manifold to be removed. IPD and ARD sell replacement kits including the intake gasket. The dealer removed and cleaned the VVTs and flushed the oil system. The cars fuel economy has improved and it runs smooth and doesn't surge at high speeds as it did before. The PCV system was costly but was done right and I am free from anymore problems. Hope this helps.

[Pennhaven]

In light of the all the comments subsequent to my original post after replacing the PCV components on my 2004 XC70, today I took the vehicle to Don Beyer Volvo in Falls Church, Va and requested the PCV system to be checked.

I quote from the notes on the service ticket: "Customer requested the PCV system to be inspected on the boost side. Tech inspected the PCV system. Customer is advised the PCV system is operating as per manufacturers specs; suction at idle and pressure when accelerating."

Can anyone definitively confirm or refute (with evidence) what Carllay was told by the dealer? Other posters have stated that there will always be negative pressure in the crankcase if the PCV breather system is functioning properly. But based on my recent test results and what Carllay was told I'm doubting this.

There are only 71,000 miles on my '04. More than half of that is highway, the rest suburban driving, not very much stop and go, engine usually fully warmed before sitting. Oil has been changed at least every 5,000 miles or annually using Valvoline Durablend (synthetic blend) up to 50,000 and full synthetic since. Since 50,000 miles I've checked my crankcase pressure with every oil change using a latex glove rubber banded on the oil filler. Initially I only checked at idle, but the previous two changes I also had my wife rev the engine to 3,000 rpm and there was still negative crankcase pressure per the glove.

However I recently read that the test really should be done under turbo boost, so after last week's oil change, using my Torque app on my smartphone to measure boost via OBDii, I put the car in Drive, held the brake pedal with my left foot and revved the engine until there was positive manifold pressure. The glove stayed sucked in right up until the boost kicked in and then it inflated, then back to suction when I cut the boost.

So it seems to me that the PCV is functioning as commonly described for idle and for cruise, but boost is another condition, and my results might confirm what the dealer told Carllay. FWIW I pulled my intake tube and checked the PTC. It is open, clean and dry, as is the line at that end from the breather box to the PTC, which is what I would expect seeing negative crankcase pressure under "cruise" conditions. It seems to me, based on Howard's description here on how the system functions, that any blockage impeding flow through the breather system under turbo boost would also impede it under cruise, so it appears there is something else going on that differentiates how the system works under boost from how it works under cruise.

So I guess what I am asking is if anyone else has actually tested crankcase pressure on our cars under boost and maintained negative pressure? That would refute the theory. Or, on the other hand, has anyone, in addition to Carllay, with a fresh PCV system also still seen positive crankcase pressure under boost? That would be further confirmation that this is how it's supposed to work.