<E28> Purchase/Maintenance Observations, Part 3 of 3

[Pearson-Franks Family <pearsonf@xxxxxxxxxxx>]

Part 3 of 3 of my long post.  More E28 look-for's:

6)  Driveline
    - Check guibo, the rubber flexdisk connecting the output of the
      tranny to the driveline.  At 100K it will be cracked, and may be
      the cause of a shudder at certain speeds (frequently 25 to 35
      mph), especially while under load.
    - Ditto the center bearing and support, but much harder to check,
      as you have to dispose of the exhaust system (well, remove
      enough to get the heat shield off, but you know what I mean!).
    - Do the traditional twist-drive-components-and-note-any-play
      of the two U-joints.  The rear one is the more likely to fail,
      and is easily observed.  Bear in mind that if they are bad,
      you will need to get the driveline rebuilt, $450ish if you
      rebuild the whole thing (recommended).

7)  Suspension, Steering and Brakes
    - There are books written on the subject of the front control
      arms, but the exec summary is:  they all die.  Symptoms of
      impending doom are shuddering when braking, especially from
      say 65 down to 45.  May get very jumpy at the steering wheel.
      There are upper and lower control arm bushings and ball joints,
      and lots of alternatives (bushing upgrades, etc.).  FAQ's
      abound.  $160-$800 in parts.
    - And, of course, the front rotors warp.  $120ish.  Always replace
      the 5mm hex that secures the rotors.  Cheap insurance.
    - The 535i boost system feels weird (the 528e is a very vanilla
      vacuum boost.)  The point is; in a perfectly healthy hydralic-
      boosted system, you can 'surprise' the system if the engine is
      running but the car is standing still by stomping the brake
      pedal hard - you can make it most of the way to the floor.  Not
      to worry; you are 'way past the point that triggers ABS, but
      tech checks for track days may be tricky - the typical M3 driver
      doing the check will panic.  Explain ahead of time!
    - With the engine running for brake boost, stand on the brake
      pedal for 30 seconds or so.  If it drifts toward the floor,
      time for a master cylinder.  Replace, don't rebuild.  $80
      to $180, +/- year and/or ABS.
    - Steering should be 'tight' when gently rocked at the center
      of travel when the engine is off.  'Clunks' may mean Pitman
      arm bushings (_bad_), loose collar nut under dash (easy) or
      bad center track rod (cheap, <$60, but obnoxious).
    - The two senders on the brake pressure regulator regularly leak.
      Replace them both, $32ish.
    - There is a 'nitrogen ball', frequently referred to as the
      'brake bomb', due to it's cartoon-bomblike appearance, that
      dies.  Symptom is a slow-to-respond brake pedal, frequently
      accompanied by a flash of the 'brake' idiot light, and/or no
      brake boost immediately after shutting down the engine.  (It
      should give several-to-many 'assists' after shutdown).  Again,
      several fine FAQ's on replacement (somewhere).  $60ish.
    - When checking the p/s and brake boost fluid level, bear in
      mind that if the engine has been running and the nitrogen ball
      is in working order, there is a inch or so of fluid in the ball.
      Fully discharge the ball by stomping the brake pedal 10-20 times
      and watch the fluid level creep up.  Adjust to the line in the
      side of the can at that point.  This applies to the 'i' only;
      as the 'e' uses vacuum boost.
    - Fluid should be pretty; not black.  There is a filter in the
      bottom of the reserviour that should be changed on the 'i'.

8)  Interior, Electrical
    - Alternator brushes ($5.50 at BavAuto) are typical 140K items.
      Two screws pop the assy off the back of the alternator to check.
    - Weird guage problems (tach or mpg guage erratic, etc.) indicate
      a possible SI battery replacement needed.  Very typical, and
      lots written on the subject.
    - Dead SI batteries may also cause the Oil Service lights to be
      on at odd times.  <$10 for batts, couple hundred for rebuilt board.
    - If batt's are OK, lights are very easily reset, refer to FAQ's
      and/or reset tools, or, for the very brave, just ground pin 7
      of the diagnostic connector, turn on the ignition (but don't start)
      for 15 seconds, turn it off, and you're done.  Many will tell you
      this procedure is highly risky, but so is cutting vegetables
      with a dull knife - sheesh!  no rocket science here.  (15 pin version)
    - Jump pins 11 to 14 for remote start.
    - Headrest up/down dies.  Easy fix, good FAQ's elsewhere. $0.
    - Just an observation:  window lift and sunroof switches were
      illuminated 'standard' in late '86 US cars on.  Easy swap,
      wires already in place, as an easy upgrade.  I got a set from
      Jason at Zionsville, very cool outfit (no affiliation, yada x 3)
      Also, they get mechanically sticky and electrically erratic if
      exposed to Armorall.  Switches can be opened and cleaned.
    - Fuse box has chronic, but easy problems.  Fuse clips corrode,
      wirebrush 'em.  Fuses corrode, replace 'em all.  Connections inside
      the box can get erratic or hot.  A real bear to troubleshoot.
    - Several chronic problems show up as 'cutting out' at any speed,
      frequently the 'main' relay, sometimes the fuel pump relay,
      sometimes the position or timing sensors.  Connections to the
      _underside_ of Fuse 6 can corrode and heat up.
    - Several handy voltages to know, measured at the battery:
      10.0v - voltage while cranking starter
      12.3v - 50% charged battery, 'at rest'
      12.7v - fully charged battery, 'at rest'
      13.6v - minimum acceptable alternator output at idle
      14.3v - maximum acceptable alternator output at revs
      Ref:  Mark Calabrese article "In the Dark?"
            March, 1996 Roundel

9)  General
    - Don't believe a _dang_ thing a salesperson says, if there
      is not documentation behind it.  "Changed the oil every 3K
      miles" if literally true means they _never_ changed the
      filter.  Semantics?  Maybe.  The car tells the real story,
      a salesperson has a car to sell.
    - Lots of exhaust replacement opinions, choose one you like.
      The E28 cats crack, but can be successfully welded for years.
    - Water in the trunk is usually a bad (hardened and/or cracked)
      rubber gasket around the taillight assy's.  Replace them both.
    - Buy a Bentley manual, and an ETM (Electronic Troubleshooting
      Manual) if you are electrically astute.
    - Check to see if it has the TRX tires.  If so, you face one of
      the classic $$$ delimmas - discount asking price $400 if tires
      OK, $1000 if tires need replacement.  Many details elsewhere.
    - For an excellent treatment of all the E- and M- numbers, check:
      http://www.unixnerd.demon.co.uk/enumber.html, John Burns' page.

That's it!  As before, comments, corrections welcome.  Larry F.

Larry Franks
Issaquah, Washington
'86 535i x 2
'83 245 GLT (Swedish iron)

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