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Old 05-12-2019, 08:35 AM   #1
bignslow
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Where is the PCV?

Does M42 have a PCV valve? I see there are 2 hoses running from the intake to the throttle body. The one in the front is just a straight hose. The one in the back has a small silver canister with electrical connector attached to it. Is that the PCV?
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Old 05-12-2019, 12:06 PM   #2
fresh_TD
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M42s have ICV's. A quick Google search would have answered your question. Yes, the piece with the electrical plug, near the firewall, is the ICV( Idle Control Valve)

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Old 05-12-2019, 02:46 PM   #3
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Fresh_TD answered half of your question, so I'd like to elaborate and say that the M42, while lacking a PCV valve, does have an oil/CCV separator built in to the valve cover. This part is not readily replaceable, nor does it need any type of service unless you are getting an extreme amount of oil in your throttle body. The exit for the separator is the forward hose that routes to the throttle body.
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Old 05-12-2019, 04:05 PM   #4
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Ok so that leads me to my next question. With engine running if I pull the oil cap off I feel a considerable amount of air and some oil splash being blown out. Is this normal? All of the other cars I've worked on the PCV system took take care of any air that is generated in the crank case.
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Old 05-12-2019, 04:19 PM   #5
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Quote:
Originally Posted by bignslow View Post
Ok so that leads me to my next question. With engine running if I pull the oil cap off I feel a considerable amount of air and some oil splash being blown out. Is this normal? All of the other cars I've worked on the PCV system took take care of any air that is generated in the crank case.
You pulled the oil cap, what did you think was going to happen? C'mon lol. Is there a particular reason why you're asking these questions. What's the goal here? Or are you just asking to ask? There's lots of info out there, do research my friend. GOOGLE

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Old 05-12-2019, 05:02 PM   #6
bignslow
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Quote:
Originally Posted by fresh_TD View Post
You pulled the oil cap, what did you think was going to happen? C'mon lol. Is there a particular reason why you're asking these questions. What's the goal here? Or are you just asking to ask? There's lots of info out there, do research my friend. GOOGLE

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This is the first engine I've ever worked on that generated enough crank case pressure to be blowing out of the oil filler and not venting out of PCV or breather. On any other car if there was pressure generated in the crank case that wasn't sufficiently venting it would start blowing oil through the seals. This is usually a symptom of PCV not working correctly or blow by.


Every other car I've seen actually has a bit of vacuum at the oil filler.



I already Googled, only thing I found was other people asking the same question. Wtf is the point of this forum if people are gonna be told to use google anyway?

This guy asked similar question. Nobody knew the answer.

http://www.318ti.org/forum/showthread.php?t=39742

Same here, just a bunch of random guesses but nobody knew for sure.
https://www.bimmerforums.com/forum/s...of-the-oil-cap

Last edited by bignslow; 05-12-2019 at 06:01 PM.
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Old 05-12-2019, 08:10 PM   #7
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I dunno why the hostility. Also dont know why Fresh_TD starting jabbering on about ICVs when the question was PCVs.

I must admit i just tried for about 10mins trying to find the one for the e30, no luck finding a concrete answer.

the e36 m42 has this listed as the PCV, maybe e30 is the same?

https://www.ecstuning.com/BMW-E36-31...ons/PCV/Valve/

little black disc thing. Unsure where it goes though, maybe it goes in the rocker cover somewhere?

that part number doesnt show up in real oem under e30 though, so im not convinced its the same as yours.

To have that much pressure in your crank case something is wrong. On the m20 the entire crank case is part of the vacuum system (you'd think this would help with the oil leaks!). Maybe it is the same on the e30 m42 (since there is no PCV listed), but on your particular engine something hasn't been installed correctly and the crank case is actually sealed up, and thus it is over pressurising due to blow by.

Last edited by e30davie; 05-12-2019 at 08:17 PM.
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Old 05-12-2019, 09:02 PM   #8
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Quote:
Originally Posted by bignslow View Post
Ok so that leads me to my next question. With engine running if I pull the oil cap off I feel a considerable amount of air and some oil splash being blown out. Is this normal? All of the other cars I've worked on the PCV system took take care of any air that is generated in the crank case.
I don't know why you would open the cap while the engine is running, but when you do so you are short-cutting the flow to oil separator/PCV system.

Are you experiencing some sort of issue with your car as this is normal operation for an M42? Remember, some of that oil is sling from the timing assy and cams.

If you want a catch can you install it in line with the forward port on the valve cover. To be clear, PCV runs from inside the VC through the plastic separator assy riveted to the interior of the VC, through the hose and to the TB.
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Old 05-12-2019, 09:28 PM   #9
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But why is his crank case pressurising to the point of "blowing out the oil filter"? (not quite sure what that means, sounds bad?
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Old 05-14-2019, 12:29 AM   #10
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If you still have the original mess under the intake there is a chance that something in there is blocking the PCV hose.

No it does not have any kind of actual PCV valve like modern cars have. There's a separator in the rocker cover but I have not heard of it being serviceable at all.

Do the mess under the intake cleanup, then after that, ignore it. Aside from doing a compression test and verifying the rings are still existing.
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Old 05-14-2019, 05:58 AM   #11
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Main reason for me even looking into this was due to an oil leak. It turned out to be unrelated but this got me wondering if there is a PCV issue.

Mess under the intake has been cleaned up and all hoses are brand new and hooked up correctly. I double checked several times and compared to others.

The car is not smoking and doesn't stink like exhaust fumes so I don't think the rings are shot but without compression test no way to be sure. The only other thing I noticed is passage inside the intake plenum where the PCV connects is super tiny. Makes me wonder if it's sufficient enough to pull out the crank case gasses.

Perhaps one of you guys can pull your oil cap and see if it's blowing out any air?
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Old 05-17-2019, 06:09 PM   #12
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They all blow air because rings do not provide a perfect seal and there is a big ol chunk of metal spinning around down the bottom. Do a compression test, otherwise don't worry.
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Old 05-17-2019, 07:26 PM   #13
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Yeah, slinging oil is just from the cam sprockets and cylinder 1 cam lobes doing their thing. I am not sure how much air you feel coming out, but some small amount seems normal just from pistons tossing around in the crankcase and whatever blow-by occurs around the rings.
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