Crankcase pressure from boost

mikesavara · Post by **mikesavara** » 31 Jan 2020, 12:07

Hi there,

I have a 2008 S40 T5 that has some crankcase pressure issues. I replaced the PCV system 2 years ago when the diaphragm tore. I have some oil leakage around the TCV valve area on the Turbo and a few days ago my rear cam cover on the intake side fell out (assuming it was from pressure). I am currently driving with the oil dip stick out to avoid seals getting pushed out, but oil is shooting everywhere due to that.

I am getting good vacuum at idle using the glove test, but I believe my car is increasing crankcase pressure when it is driving at boost - how do I test this theory, since I can't get it to boost in park?

If it is having excess crankcase pressure at boost, what are my remedies? I've been reading about something called a "PTC" nipple but I'm not sure where that lives on the s40 - somewhere on the intake?

I also have read about a Hollow Screw or Banjo Bolt and bought one from FCP but again, not 100% where that lives in order to replace it. I heard they get clogged with carbon and can cause these symptoms. Is that in the IM?

I also think it's possible that my TCV valve is broken and needs replacing, but I'm not getting any CEL or limited boost feeling. The TCV valve area may be leaking just due to the pressure issues.

Any help is appreciated! I can replace the PCV system again but don't want to do that if it's not useful.

Post by **RickHaleParker** » 02 Feb 2020, 03:37

It sounds like you are getting Blowby, to much for the PCV system to process. Is there a raw gas smell coming from the dipstick tube? You can use a plastic hose over the dipstick tube to find out.

mikesavara · Post by **mikesavara** » 04 Feb 2020, 21:45

Hey! I'll take a sniff soon - lots of oil is coming out of the dipstick tube since i've run it without the dipstick fully in to prevent seals being pushed out.

I also tested using a manometer - I got -.41 PSI at Idle and upwards of 2.0 PSI (positive) when boosting. This makes me think that this is when the blowby/positive crankcase pressure is happening.

I am going to replace the PCV system and check the lines going into the sump, as well as the PCV Banjo Bolt going into the IM to see if that changes anything with the pressure in the system.

One other thing: I may have screwed up and put in slightly too much oil, like maybe .5-1 extra quart. Stupid move. Could this cause my woes?

Post by **RickHaleParker** » 04 Feb 2020, 23:01

mikesavara wrote: ↑04 Feb 2020, 21:45 One other thing: I may have screwed up and put in slightly too much oil, like maybe .5-1 extra quart. Stupid move. Could this cause my woes?

If you see any oil foaming or low oil pressure correct that immediately! By doing a oil and filter change.

A little over would be much of a problem but if it is too much over, Air and Oil aerates ( Crankshaft dipping into the Oil reserve) . Which can lead to Catastrophic engine failure. Oil pumps are designed to pump liquid not foam.

If it is blowby. It might be a stuck ring. It is possible to unstuck rings with Seafoam.

The data from a compression test would be real helpful.

Mikesavara1 · Post by **Mikesavara1** » 11 Feb 2020, 19:50

Hey all, so I'm scheduling an inspection later but I replaced the PCV system including the two hoses and today I had a rear cam seal pop out due to pressure. The car has vacuum at idle but generates crankcase pressure In excess of 2 psi when boosting still. Can a faulty turbo cause this? Like if it's leaking or the TCV is slowed (it's currently covered in oil) could this cause pressure to go to the crankcase at boost?

Mikesavara1 · Post by **Mikesavara1** » 11 Feb 2020, 19:52

Also, the oil level is back to a normal amount now. I don't think it's the rings causing this cause if I'm at idle, and the car is parked the vacuum remains in crankcase pressure when revving, it's only when boost is active that positive pressure happens.

Post by **jimmy57** » 12 Feb 2020, 10:05

: InkedP1 turbo_LI.jpg (596.92 KiB) Viewed 2712 times

On the turbo on P1 models is a check valve fitting that is supposed to let crankcase pressure in but vacuum lifts the ball and seals it. The check valve goes in the location circled on the turbo pic. The ball may be gummed up, lifted and stuck. Or the hose to it is crimped or obstructed.

mikesavara · Post by **mikesavara** » 12 Feb 2020, 12:22

Thank you so much Jimmy57! I think that is a really good lead. I have oil on the turbo, so it makes me think that there is an issue with this breather hose assembly. I believe this is the part https://www.fcpeuro.com/products/volvo- ... 24#fitment

I have ordered this from Volvo dealership to be delivered tomorrow and I'll try to take it apart shortly. I think it should be fairly easy to get to from the top of the engine with a crowfoot wrench and some persistence. Thank you all so much for all the support! Volvo wanted to spend "2-3 hours" of diagnostic time working on this because I've been working on it on my own. This system isn't that complicated, just takes a lot of trial and error sometimes...

Mikesavara1 · Post by **Mikesavara1** » 22 Feb 2020, 08:36

Wanted to loop back with this thread and let folks know that I believe this issue is fixed! I replaced the check valve (it's harder than I thought, important to get a internal snap ring pliers) and took it for a test drive with my manometer set up. It still goes above and generates positive crankcase pressure, but to a lesser degree and only at full boost. I believe this is likely normal, atleast for a car with 172k on the engine. The good news is that no seals have popped out all week and the engine is dry. Now to do a deep clean of the engine bay after all that oil getting thrown around before! Thank you all!