+ Reply to Thread
Results 1 to 9 of 9
  1. #1
    Registered Member
    Location
    BRONX, NY, United States
    Member No: 104792 DAGERM50 is an unknown quantity at this point DAGERM50's Avatar
    Join Date
    Mar 2004
    Posts
    126
    Rep Power
    0


    Yes | No

    valve stem seals

    hi guys, how can you tell if you need new valve stem seals? what are the symptoms? your help is greatly appreciated.


  2. #2
    Registered Member
    Location
    Germantown, MD, United States
    Member No: 11857 gkrea1 is an unknown quantity at this point gkrea1's Avatar
    Join Date
    Jul 2001
    Posts
    2,227
    Rep Power
    0


    Yes | No

    Search archives for more details, but...

    The two commom symptoms are blue smoke on start up and higher than normal oil consumption. What usually happens is oil leaks around the seals while the car sits and so you have a few drops in teh combustion chambers after is sits overnight. Once it's running you'll burn a little more, too, but probably not enough to cause a blue exhaust. I would guess that it isn't good for the O2 sensors of which you have at least two (or is it four?).
    Greg Rea
    1986 E24 arctic blue turbo shark
    1989 E32/M30 white whale

  3. #3
    Inner Circle Member Inner Circle Member
    Location
    Castro Valley, CA, United States
    Member No: 13814
    Inner Circle ©156 since: Aug 14, 2003 cheung1 is an unknown quantity at this point cheung1's Avatar
    Join Date
    Sep 2001
    Posts
    2,485
    Rep Power
    0


    Yes | No

    I believe mine has worn seals but harmless

    Since I acquired the 88 750 three years ago oil consumption has been steady around 1 quart per 700 miles, and I attribute the oil loss as a result of worn valve stem seals, because the entire system otherwise works fine. I don't particularly see blue smoke upon engine start, though. Gas mileages before and after I changed out the O2 sensors were much the same, and if there is any discrepancy, it is the mileage after sensor replacement that has dropped slightly. Thus I conclude that the two old O2 sensors were not particularly damaged because of stem seal leak (or whatever reason that causes oil consumption).

    Funny thing is that by adding 1 quart every 700 miles the effective oil life stays around 5000 miles even if I don't change oil forever (for detail see my post below).Patrick C 88 750 137K

  4. #4
    Registered Member
    Location
    Sydney, , Australia
    Member No: 93706 thebottomlesspit is an unknown quantity at this point thebottomlesspit's Avatar
    Join Date
    Nov 2003
    Posts
    292
    Rep Power
    0


    Yes | No

    You can tell by...

    Hi,

    Remove some spark plugs (not easy on the 750!) and see what they look like. If they have wet oil on them, your stem seals are shot.
    Mine were. Smoke after extended cranking, and a little smokey at high revs.

    Hope this helps.

    John-STATIONARY- 1990 750iL Glacier Blue 145k

  5. #5
    PaParon
    Guest
    Location
    , ,
    Member No: PaParon's Avatar


    Yes | No

    Re: valve stem seals

    Can you replace the valve stem seals while the heads are on the engine?

  6. #6
    Registered Member
    Location
    , ,
    Member No: 13858 elmerblues is an unknown quantity at this point elmerblues's Avatar
    Join Date
    Sep 2001
    Posts
    238
    Rep Power
    0


    Yes | No

    Re: valve stem seals

    Excessive oil consumption (mine 1 liter/800km), blue smoke when you heavily deaccelarate, idle a certain time and after that accelarate.

    When you pull the intake manifolds you can look insided the intake ports (seeing the intake valves) and when the valve stem seals are worn, you will see the intake valves covered in oil <b><font size=2 face="Verdana">Sean750</b></font>
    <p><font size=1 face="Verdana">BMW 750i '88 Porsche 928S '86
    --------------------------
    <a href="http://bmwe32.student.utwente.nl/" target="_blank"><i><font color="blue">Johan & Sean's E32 page....a technical E32 reference</i></font></a>
    <a href="http://bmwe32.student.utwente.nl/" target="_blank" class="postlink"><img src="http://bmwe32.student.utwente.nl/sean750/screendumpSite.jpg" border="0" />

  7. #7
    Registered Member
    Location
    Sydney, , Australia
    Member No: 93706 thebottomlesspit is an unknown quantity at this point thebottomlesspit's Avatar
    Join Date
    Nov 2003
    Posts
    292
    Rep Power
    0


    Yes | No

    Yes, but with MASSIVE difficulty. You wouldn't.

    -STATIONARY- 1990 750iL Glacier Blue 145k

  8. #8
    Scott Marzahl
    Guest
    Location
    , ,
    Member No: Scott Marzahl's Avatar


    Yes | No

    Pat, did you ever change yours out yet?

    Oil burning is also not good for the "cats". Changing the oil seals is not that big a deal if you are mechanically inclined. You need a spark plug compression adapter to hold the valves up using compressed air and of course numero uno is the correct valve spring compressor tool which is available by rental from Koala motorsports.
    I was at the point of changing mine, intakes off, rocker covers off, but the PCV system was the big cuprit on my car. My intakes were filled with oil. If I have an extra day to kill in the future I will end up changing out my seals as preventative maintenance.

  9. #9
    Inner Circle Member Inner Circle Member
    Location
    Castro Valley, CA, United States
    Member No: 13814
    Inner Circle ©156 since: Aug 14, 2003 cheung1 is an unknown quantity at this point cheung1's Avatar
    Join Date
    Sep 2001
    Posts
    2,485
    Rep Power
    0


    Yes | No

    No I haven't. This URL calls for bigger stem valve

    George Mann on this board explained why it is difficult to change valve stem seals (I suppose same as v.s. guides) on a M-30, and again I suppose the reasoning applies to M-70, which also features an aluminum head. Thanks for pointing out the potential damage to the cat. I don't know how to judge the way to fix but since I have no other reason to open up the head I probably keep it this way until I fail a smog test.Patrick C 88 750 137K

+ Reply to Thread


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

     

Bookmarks

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
1e2 Forum