N52/N51 Vaccume Line Replacement

Fritzer · 06-01-2020, 07:13 PM

I'm pretty confident I have a vacuum leak and it's causing some of my rough idle issues. Considering they are all original and my car it at 155,xxx miles, I might as well get it done. I can't seem to find a reliable DIY or guide for this. Does anyone have any links that would be of use? As well as what size I should purchase? Thank you.

hassmaschine · 06-02-2020, 12:21 AM

They're all plastic, and AFAIK, there's only a couple lines related to the PCV heater system. The 328i has even less vac lines than the 330i due to the integrated PCV in the valve cover.

I think the reason you don't see any DIY or much info, is because it's not really a common issue. As long as you don't touch the plastic lines (which crumble into a million pieces when you do), the chances of a vac leak are really small.

Could your VC be cracked or leaking? That seems far more likely to me.

heh, thinking about this, my E30 still has some original rubber. I'd really like to replace the aging fuel lines. If they were plastic like a modern BMW though, I bet they'd have broken ages ago.

AoS810 · 06-02-2020, 11:52 AM

I recently replaced the CCV hose from the rear of valve cover to the intake manifold on my N51 and that unfortunately didn't really make a difference with my minor rough idle issues.

Interested in this thread to see what else can be done to address it! Fritzer I also sometimes still get that weird gear-shift selection rpm fluctuation as well, do you still have this issue?

Our vehicles have very similar mileage, I'm at 157K now.

nsjames · 06-05-2020, 04:53 PM

would smoke test it before I started monkeying with it.

06-01-2020, 07:13 PM	#1
Fritzer No one sleep in Tokyo 945 Rep 1,507 Posts Drives: 2011 E90 328i//1995 E34 530i Join Date: Oct 2018 Location: San Diego, California -> Austin, Texas iTrader: (3)	N52/N51 Vaccume Line Replacement I'm pretty confident I have a vacuum leak and it's causing some of my rough idle issues. Considering they are all original and my car it at 155,xxx miles, I might as well get it done. I can't seem to find a reliable DIY or guide for this. Does anyone have any links that would be of use? As well as what size I should purchase? Thank you. __________________ 2011 E90 328i, 1995 E34 530i, 1992 E32 740i, 1991 E34 525i
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06-02-2020, 12:21 AM	#2
hassmaschine Major General 3966 Rep 7,215 Posts Drives: "NBO" 330i Join Date: Jun 2014 Location: earth iTrader: (0)	They're all plastic, and AFAIK, there's only a couple lines related to the PCV heater system. The 328i has even less vac lines than the 330i due to the integrated PCV in the valve cover. I think the reason you don't see any DIY or much info, is because it's not really a common issue. As long as you don't touch the plastic lines (which crumble into a million pieces when you do), the chances of a vac leak are really small. Could your VC be cracked or leaking? That seems far more likely to me. heh, thinking about this, my E30 still has some original rubber. I'd really like to replace the aging fuel lines. If they were plastic like a modern BMW though, I bet they'd have broken ages ago.
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06-02-2020, 11:52 AM	#3
AoS810 Lieutenant 97 Rep 414 Posts Drives: 2008 E90 N51, 2011 E91 N52 Join Date: Oct 2009 Location: Los Angeles, CA iTrader: (6)	I recently replaced the CCV hose from the rear of valve cover to the intake manifold on my N51 and that unfortunately didn't really make a difference with my minor rough idle issues. Interested in this thread to see what else can be done to address it! Fritzer I also sometimes still get that weird gear-shift selection rpm fluctuation as well, do you still have this issue? Our vehicles have very similar mileage, I'm at 157K now.
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06-05-2020, 04:53 PM	#4
nsjames Brigadier General 2440 Rep 4,330 Posts Drives: 08 328xi Touring Join Date: May 2017 Location: ohio iTrader: (0)	would smoke test it before I started monkeying with it.
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