Best Cheap Test for BMW N55 PCV Valve/System - X3 X5 35i 535i 335i

Sharing the method I used to test the PCV system on a 2016 BMW X5 PCV system. There are a lot of videos and tests out there, I didn't find any that showed me exactly what I wanted to know so I made this video with some more detail. Hopefully this helps someone diagnose their system.
Products used in this video (affiliate):
Manometer: amzn.to/3vlYErT
Oil Cap: amzn.to/3H3NACk

[@Salmomlox]

I miss your engineering videos. Very informative and helpful. Thank you, Joe. You're the best. 👍🏻

[@Rightbackatchya]

I carried out this test on my N55 that started to have a squealing rear main seal. Turns out I was getting more than double the nominal PCV pressure after highway driving. Have replaced the diaphragm PCV valve/regulator with pressure returning to normal at this stage, but will likely replace the overall valve cover to be sure. Very happy to have this identified because replacing a rear main seal is a MAJOR job.

[@Rightbackatchya]

Thank you for the best and very approachable explanation of how to diagnose this system!

[@derekkchung]

Very good and detail oriented. You are the kind of people who can achieve.

[@meslzr1]

Loved this video, and I wouldn't even dare to check it myself

[@aleschenfelder3559]

Yes! Finally! Thank you sir! This video needs to make its way to the forums, I have yet to see any troubleshooting like you demonstrated. All I’ve seen and heard is what you debunked, and I honestly thought they were busts too but I don’t have a very good understanding of the vacuum system on the n55. I am currently chasing an issue where the vacuum lines are filling with oil as well as the vacuum chamber in the valve cover and I am hoping it is an internal crack and a new cover remedies the issue. I will surely be adding your inexpensive setup to my tool box! Great video!

[@JoeDidItTV]

Yes! I test the pressure every time I change the oil now, takes 2 minutes but can save thousands if the system has failed. Mainly because you will be damaging your crank shaft seals and not know until it’s too late. As for the other tests I’ve seen like using a lighter, it is actually very difficult to do because there’s a lot of wind in the engine bay.

[@aleschenfelder3559]

@@JoeDidItTV agreed, I couldn’t tell if it was the wind or valve. Upon further research I think my vacuum pump is going out here soon and need to get it replaced before a catastrophic failure. It seems although the pump supplies vacuum through the hose routed across the VC oil can still travel upwards through the line into the vacuum chamber.

[@janangmixvlogs]

Watching sending support ❤❤

[@erikforsberg251]

I have a problem where i get 60mbar of positive pressure instead of 50mbar negative pressure and the car is burning oil. Any input what could cause that?

[@JoeDidItTV]

There are a number of potential causes of this. First off, the positive pressure is caused by blow by from the pistons, if you’re lucky it could just be a clogged port on the top of the PCV diaphragm. The small port that I connect the hose to in the end of this video. Check to make sure it’s not blocked.

[@JoeDidItTV]

The reason it’s positive instead of negative is because something is preventing your intake vacuum from sucking that excess pressure down. One possibility is a bad or stuck valve.

[@erikforsberg251]

I applied vacuum to the top side of the diaphragm and then got negative pressure meaauring through the oil cap. Like the spring in the diaphragm was broken!? Then i changed the valve cover and i got normal -50mbar and all is good again.

[@nitrovdubs9795]

I have same vehicle and engine combo in my wife’s 2011. It has small hiccup idle just changed plugs/coils and valve cover. Did you figure out what was wrong with yours?

[@JoeDidItTV]

I changed plugs, coil packs, serpentine belt (with the tensioner and idler pulleys too it’s a kit). Then I did a bottle of Techron fuel system cleaner. In that order, all of them helped a little and the stutter is almost completely gone. All of these are things that should be done anyway so it wasn’t a waste of $$. But you could start with the fuel cleaner because it’s the least expensive option.

[@nitrovdubs9795]

@@JoeDidItTV thank you!!

[@JoeDidItTV]

Actually I did the belt before the plugs, but the fuel system cleaner made a noticeable difference. There’s still a little excessive vibration but that might just be normal aging of the motor mounts. It’s so minor that a dealer would tell me I’m crazy if I mention it for sure. No more idle hunting tho.

[@SuAmigo12]

@@JoeDidItTV , were you getting any Service Engine Soon fault code that led you to suspect faulty PCV/CCV valve? I am changing down annoying P1112F issue. Already replaced valvetronic sensor gasket flange and crankcase vent hose as they failed smoke test.

[@andrewperkins4047]

I changed the turbo solenoid and it ran better for a couple weeks. Then jitter in the tensioner and P0112F again. My next step is to check that again, and change spark plugs. I had a bad pcv valve - loud whistle from seal, so I changed the valve cover. Still has P0112F. PCV was cracked. Not totally sure. I replaced rotted hose on boost solenoid and new solenoid, but can’t imagine it failed so quickly. Must be an internal leak. I saw no smoke leaks when I tested.

[@sunyoungg5634]

S55 PCV 'SQUEAL' - Easy Fix (so you don't have to replace the entire valve cover) - search that forum thread title and see this great video linked

[@mircebob]

Just done that to my F80 M3, replaced the pcv valve with a new klifex one from amazon. Cut the old one out, fit the new pcv vavle using jb weld and optionally you drill 4 small vent holes under the breather nipple on the pcv if you decide to gut it out completely.

[@JoeDidItTV]

For sure that’s a good option. I wanted to show an effective way to test if a repair is necessary with this video.

[@sunyoungg5634]

@@mircebob I don't understand what it is you've done - is it the oil filler cap that you've gutted and now have 4 small vent holes in it? - if so that may allow more air into the engines intake downstream of the mass air flow measurement device.

[@mircebob]

@@sunyoungg5634 no, i was talking about the PCV valve itself that sits on the valve cover. Not the oil cap, my bad.