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Thread: Vacuum Leaks help

  1. #1
    Join Date
    Jan 2015
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    US
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    160
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    1995 bmw 325is

    Vacuum Leaks help

    Ok so I have been extremely busy for a long time but I want to carve out some time to do some work on my E36. I want to tackle vacuum leaks under the hood. I have seen some videos on youtube with other makes of vehicles where they "smoke" out the leaks through the brake booster or by removing the throttle body intake hose. Is there a how to anywhere on this site to show the best way to do this on my model in particular? I've been hearing a little hissing for a while and I'm sure there's some hoses or clamps that can be tightened somewhere plus I feel like I've lost a little power in the last year and it's been irking me for a while. Any suggestions on what to do and how?

  2. #2
    Join Date
    Feb 2005
    Location
    Long Island, NY
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    6,479
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    1995 M3 - 2007 X5
    Quote Originally Posted by innerbimmer View Post
    Ok so I have been extremely busy for a long time but I want to carve out some time to do some work on my E36. I want to tackle vacuum leaks under the hood. I have seen some videos on youtube with other makes of vehicles where they "smoke" out the leaks through the brake booster or by removing the throttle body intake hose. Is there a how to anywhere on this site to show the best way to do this on my model in particular? I've been hearing a little hissing for a while and I'm sure there's some hoses or clamps that can be tightened somewhere plus I feel like I've lost a little power in the last year and it's been irking me for a while. Any suggestions on what to do and how?
    An old trick is to spray carb cleaner around the throttle body, intake elbow, manifold etc. The RPMs will dip if you hit a leak.

  3. #3
    Join Date
    May 2017
    Location
    Mb, Canada
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    75
    My Cars
    1998 BMW 328ic
    Take off the easy to remove intake system components and then check the easy stuff first. This consists of the intake bellows and all the easily accessed vacuum hoses.PLUS check all the hose plastic tee's for cracks or breakage. Next for the inaccessable hoses you have the option of using an inspection camera or a inspection mirror. Worse case you may want to take the whole intake out and correct everything all at once. This is what I ended up doing as I also had to replace a bunch of the small cooling system hoses at the same time. There is a rubber grommet that the ICV goes into at the bottom of the intake manifold and one that goes into the intake bellows as well. Sometimes they dry out and you lose the seal.

    For what it's worth unless you are extremely cash strapped I would just pull the manifold so you have easy access to all the vacuum systems. I replaced my intake manifold gaskets, cleaned all my injectors and did the cooling hoses while I was in there. Most of the components are fairly inexpensive and you shouldn't have to do it again. BTW, you can just use locally available rubber vacuum hose, no need for OEM here. I had a lot of vacuum hoses with the ends split and they were leaking but it was hard to tell just by a casual inspection. Same with the plastic tee's although my car seems to have a lot of these types of components that are very brittle.

    Don B

  4. #4
    Join Date
    Jan 2015
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    US
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    My Cars
    1995 bmw 325is
    Hey what do you mean by "cleaned all my injectors"? How do you clean them? Because I'm still trying to narrow down a stuttering-start issue and I just thought maybe one or more of my injectors could be a culprit. Anyway I have replaced my injectors on a saturn I used to own. It was pretty easy to do but just by the looks of the 325 it could be a little more time consuming. Plus I never knew they could be cleaned.

  5. #5
    Join Date
    May 2012
    Location
    Central Wisconsin
    Posts
    640
    My Cars
    '94 325i, '93 325is
    Injectors are easy to install/remove, unhook the fuel lines, and remove the 2 m6 screws holding the rail down and it pulls right out. I prefer the OEM vacuum line because it lasts way longer than parts store replacement hose. It is cheap from FCPEuro. It would be good to replace the orange intake manifold seals to the head, the throttle body orange seal , etc. Remember the car is 23 years old... You won't find tiny vacuum leaks with carb cleaner spraying method.
    '94 325i Sedan, Arctic Gray: UUC LTW FW, EVO 3 and DSSR, +.020 Maxsil pistons, ASC delete, Eibach shocks/springs, 16" contour reps 238k
    '93 325is Coupe, Schwarz, work beater 299k
    '89 325i Vert, Alpine White: 5spd swapped. Sold
    '04 Toyota Sienna XLE Limited AWD, In progress swapping to M50/G250, http://www.wibimmers.com/board/index...nna-25i-build/
    '05 Volvo V70 R, 6mt, mostly stock, kid hauler 200k Sold
    '85 Toyota LandCruiser: Lifted, gas hog. 205k

  6. #6
    Join Date
    May 2017
    Location
    Mb, Canada
    Posts
    75
    My Cars
    1998 BMW 328ic
    For injector cleaning, I used carb cleaner, put in new pintles, screens and o-rings on all the injectors. To clean the injectors I made a sealable rubber end that I could pressurize with air on the end away from the injector. You hookup the injector to the rubber fitting (tube) with a hose clamp and then fill the tube with some carb cleaner. You then attach your air line and pressurize the system, don't use too much pressure and be sure to wear eye protection in case it lets go. Having hooked this up you energize the injector with 12 volts in short bursts while you have the end of the injector in a jar. The injector will spray and once it's spraying well you are done. You may not want to rebuild your injectors but my pintles were brittle and cracked as soon as I even looked at them. There are a couple of you-tube videos on how to do all of this and it's not too difficult. Worked well for me.

    Don B

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