[Prev][Next][Index][Thread]

FAQ part 5/10

Section 12.4:	Adjusting valves

A:	(by Justin Seiferth: seiferth@domain.elided
	Peter LaPine: plapine@domain.elided
	Don Eilenberger: dje@domain.elided

>I plan to attempt to do a valve adjustment on my car this weekend (my
>first time!).  I have a feeling that the job is really easy, but that
>having someone experienced offering tips like pointing to the valves
>:-) would be handy.  I have the Bentley book, which is reasonably
>clear, but I was wondering if one of you old pros could recall some of
>the "lightbulbs" that went on the first time you did it yourself.

>Before starting, looking through the guide, here are some questions
>that arise:

>1) Crankshaft rotation is done on the "vibration damper bolt".  Where
>is that?  Figure 4-25 of Bentley shows the vibration damper: is the
>bolt where the pictured wrench is securing it?  Or is it somewhere
>else?

I don't know about the 325 engine.. but I find it MUCH easier to
rotate the engine using the nut on the alternator. I can fit a large
socket (I think 19mm) and a 1/2" ratchet on this nut.. no way I could
get it on the crank "vibration-damper-bolt" - which is the bolt at
the end of the crankshaft which holds the damper on. (Dead center
at the bottom of the engine, facing the radiator). You may have
to use one hand to put some additional tension on the alternator
belt when turning it.. but it sure beats trying to get a wrench
all the way down to the crankshaft. Always turn clockwise...(or the
nut will loosen up).

Second opinion:
On the 535i, I remove the fan clutch assembly by loosening the large
nut immediately behind the fan clutch.  NOTE: it is reverse threaded!!!
So turn it CLOCKWISE (instead of counterclockwise) to loosen it.  I
use channel locks to remove it.  Then I use a large screwdriver blade
against the heads of the bolts which fasten the fan pulley to the
water pump to turn the engine over to potition the cam lobes for
appropriate valve adjustment


                                o

                            o       o


                            o       o

                                o


Place the screwdriver blade against the top of bolt head in
clock position 1 and against the bottom of the bolt head in
clock position 7.  With the handle sticking out past position
1, push down and the engine will turn over.  Besure to keep pressure
toward the engine.  Be careful not to slip and punch a hole
in your radiator...


>2) The stiff wire tool: can I use a coat hanger?

IF you can find one the right size.. I usually use a allen wrench
(don't remember what size..) it is very stiff, and has the
needed "L" shaped hook in it. Rummage through your tools.. you'll
find something that works. I sorta think a coat hanger wire might
not be strong enough.

>3) Do I really need to take my plugs out to do the valves?  I'm
>planning on replacing them anywaythis weekend as part of the
>Inspection II; does this really help.

YES! Unless you're godzilla! IF you don't take out the plugs, you'll
be attempting to turn the engine over against cylinder compression.
Removing the plugs makes this a WHOLE LOT EASIER! (And if you're
replacing the plugs.. why NOT?)

>4) Figure 4-27 shows the feeler gauge being inserted.  Where exactly
>is it going - between the rocker eccentric and the top of the valve
>stem?

Exactly. And - to really adjust it correctly, I make certain that the cam
lobe is facing exactly away from the rocker mating surface when I make the
adjustment. This does require more turns of the crankshaft-- but makes for
a better job.

Just make all the valves have the same tension- that's important because
you don't want the relative  clearances to change when the engine heats up.

I typically:

        1. loosen the nut

        2. place the feeler gauge between the concentric disk
           and the valve stem

        3. press the concentric disk towards the valve stem and
           at the same time tighten the nut

        4. recheck the clearance (should be a SLIGHT drag -
           you shouldn't have to force the gauge in, nor
           should it slide in with no resistance - just some...
           - this 'feel' is what comes with experience...)
           and repeat, if necessary, until it's right.

           this is where you can spend some time.  I usually
           have 2 or 3 that require diddling back and forth
           a few times until they're right.  Remember, since
           you're taking the time to do it, you may as well
           get it right...


>5) What exactly is being accomplished by adjusting the valve
>clearances - if the valve is closed, and there's clearance between the
>rocker and the stem, why should it matter if the tolerances are off a
>bit? What would the performance implications be?

You're setting the valves so they open the correct amount, and at the
correct time in relation to the ignition/exhaust cycles. The tolerances
are surprisingly small - minor changes do lead to rough idle. As far
as performance.. if they're way to tight, you stand a good chance of
burning the valves (they aren't closed enough to cool), and ruining
a camshaft (constant contact lobe/lifter - can lead to oil starvation
and galling of the cam). If they're too loose, about all you'll have
it lots of noise and a loss of power (not open long enough to let all
the mixture in, or all the exhaust out). I guess it is possible that
the extra impact on the cam/rocker could also cause some damage if they're
too loose.. but I've never seen this personally.

>6) Any tips on different clearances I might want?  '86 325

Set the plug gaps to at least the BMW specs... a bit over won't hurt
(0.002-4) and on 535's is known to improve the idle.  (NOTE, this offers
no advantage on the M20 (2.5/2.7 liter) engines.)

>Any other useful tips

Several to be exact:

1. Do it with the engine stone cold! - Meaning do it after the engine
has sat not running overnight! I have found from experience that you
cannot adjust BMW valves on an engine that is even a little warm.. the
aluminum head changes dimensions so much with temperature that by the
time you've gone from one end of the valve train to the other, the
settings you set at the beginning are not anything like what you set
for the last one.

2. Do it at least twice.. don't ask me why, but BMW valves always seem
to require this. The first time through you get them close.. the second
time you'll get them dead on. I always use three feeler guages. The 1st
is 0.001" smaller than spec, the 2nd is the specified spec, the 3rd is
0.001 larger than spec. When you're done #1 should go through with NO
drag. #2 should go through with a bit of drag. #3 should be very hard
to push through.

3. Get angled feeler gauges (Sears used to have them) that are made
for adjusting valves. The layout of the BMW valve train is such that
the slight (30 deg. or so) angle on the end of the feelers makes the
job MUCH easier.

4. Don't do it when you're likely to be in a rush. If you know you have
to go somewhere in 3 hours, wait until the next day.. the first time
you do this it will take a while, and the job will go better if there
isn't an S.O. popping out every so often asking "are you almost done??
We have to leave soon..."

5. Don't drink and adjust valves (a lesson I learned when I owned a
Jag XKE - which required REMOVING the twin cams to adjust the valves).

6. Buy a new valve cover gasket. Old ones USUALLY work - but when they
don't it's a pain to have to remove everything to get at it again!

7. Change the oil afterwards.. just in case any crap fell in while the
engine is open.

8. While buying the valve cover gasket.. get a few extras of the lock
nut and little bolt that go though the eccentric adjuster. I've never
broken one.. but they are very small and look easy to bust (which would
ruin your day if you don't have a spare). I use the 10MM box wrench from
my trunk tool kit on these - it's about 6" long and seems to provide just
enough leverage to keep me from overtightening these. I don't know what
the torque spec is on them, but it would be difficult to get a wrench in
there anyway while attempting to keep the eccentric from moving.

9. Doing the actual adjustment.. I usually loosen the nut enough so the
eccentric moves easily, then insert the feeler and move the eccentric
until I can feel it contact the feeler/valve stem. I then tighten the nut
just a bit, and try moving the feeler. You'll find that tightening the nut
tends to close up the adjustment, so you will have to now move the
eccentric with the slightly tightened nut. When you think you have it
right - use feelers 1, 2 & 3 to check. If it feels OK - then tighten
the nut a bit more, and check with the feelers.  After you do the
first few, this will become easier. Make sure you check after each
tightening of the nut with the feelers.. the clearance does tend to
change *just* a bit. Don't overtighten the nut/bolt - I use 3 fingers
on the end of the 6" wrench.. haven't had one break or come loose yet!

10. Replacing the plugs.. hopefully you're using the silver ones that
BMW specs.. others just don't seem to work as well. You should not
need anti-seeze (the plugs are nickel plated).. and you should TORQUE
them to the correct specs. Overtighten and you stand a chance of
stripping the threads in the head. Undertighten and they'll back out
while driving.. a good torque wrench (Sears ones are OK) is a cheap
long-term investment that any driveway mechanic SHOULD have.

==============================
+ Section 12.5:	Spark plg lube

A:	(by Charles:CHMORRIS@domain.elided)

Steve Bernstein recently recommended using oil on the spark plug
threads. While I agree that some lubrication is desirable, I have
also read that using oil can cause problems later on,
because the temperature is so high that the oil can carbonize. This
could cause damage to the threads of the head when removing the plug.
  I have used Wuerth CU-800 (a high-temperature copper paste) on
all my BMW engines (in fact the box recommends it for plug threads)
and have never had any problems...not so for motor oil!
This stuff is VERY expensive (I think I paid $18 for the large
tube) but it's wonderful when used on exhaust manifold nuts,
catalytic converter flanges, etc... VERY easy to remove the nuts
even when rusty on the outside!

<<<<<	(by Ben:bthongsa@domain.elided)

Putting regular motor oil on spark plug threads prior to installation
in probably not a very good idea.  In the intense head of the area,
the motor oil will break down and gum up the threads, making removal
of the plugs difficult, and possibly causing the threads to pull
out of the head as well.

If you feel compelled to lubricate the threads prior to installation,
use some kind of copper anti-seize compound.  This stuff is designed
to withstand intense heat, and will serve the purpose of making
installation/removal easier.

Bosch does not recommend the use of any thread lubricant with their
plugs in most cases.  Apparently the threads are nickel plated,
and do not need extra lubrication.

A good rule of thumb for tightening new plugs is to hand-install them
until the crush washer seats onto the head, then tighten an extra
1/4 turn.  This is for plugs with washers (obviously).  Taper-seat
plugs should be hand-seated, then turned an extra 1/16th turn.
A torque wrench is ideal, but this method works as well.  (all of this
info is in the Bosch Spark Plug Catalog)

==============================
+ Section 12.6:	Loose Big 6 Oil Spray Bar Bolts

(Editor's note:
The hollow bolts that hold and take oil to the bar which
provides oil to the cam lobes on the big 6 engines are
prone to loosen up, with potentially serious consequences!)

A:	(by dje@domain.elided (Don Eilenberger))

Actually - there are two of them to look for (and it turns out
BMW-Alfred of the 528i/533i's has had them come loose also,
plus my mechanic friend ALSO said "they all do that...").

So.. whilst the valve cover is off for your periodic valve
adjustments - check the TWO bolts (13mm heads) that go
THROUGH the oil spray bar line that runs forwards/back on
top of the engine (over the camshaft).  They'll be pretty
obvious.

I tightened to something like 10-11 ft/lbs - more than this
I wouldn't go - these are hollow bolts - and possibly
aluminum - so there is a GOOD chance of shearing off
the heads if you overtighten them.  At about where I
stopped, I could just see a bit of deformation of the
actual oil spray line..


	(by "norm (n.) grills" <grills@domain.elided>)

OK - I remembered there being a tech bulletin on this so I called my
local dealer and confirmed it.  The fix is to replace the crush rings
(TWO per bolt, one above and one below the spray bar), Locktite the
threads with BLUE (242) and torque minimally (5 ft/lbs) or two fingers,
whichever comes first.  The Locktite will hold the bolt.


- - ---------------------------------------------------------------------------
Chapter 13.0: Brakes

Section 13.0: How to change fluid

	(by hertz!efd@domain.elided (Ed Dennison))
	Subject: Bleeding E36 Brakes w/ABS

In order to properly bleed the brakes on an E36 3-series
BMW equipped with ABS (which is all of them in North
America), it is necessary to open an internal valve within
the ABS hydraulic unit.  A BMW dealer does this by connecting
the BMW Test/Service unit to a diagnostic plug on the ABS
unit, then choosing the correct choice from the screen
menu.  Failure to follow this procedure can leave air in
the system.

No info on how to DIY this!


Section 13.1:	Why should i change brake fluid?

A:	(by Kinports Brian: kinports_brian@domain.elided)

The main reasons brake fluid requires regular changing is internal
contamination  and water mixed in the system.  Contamination comes from any
number of sources from calipers to brake lines to master cylinders, etc.  Brake
fluid is hydroscopic (absorbs water).  The older brake fluid gets the more
water it can absorb particularly in wetter climates as one person suggested.

This water/brake fluid will easily boil under continual hard braking
conditions.  When this happens, air (boiled water) is now in the brake system,
pand this air is compressible.  In the extreme case, when you push the brake
pedal, it will go all the way to the floor compressing the air without
providing firm breaking.

Higher temperature brake fluid is an excellent remedy that helps to reduce the
chance for boiling.  I have found that the Mercedes factory fluid (good to 500
degrees is excellent).  Castrol LMA is 400+ degrees and is usually adequate for
regular driving conditions.  It is quite common to change fluid or bleed brakes
during track sessions with my 2002.

One other way to keep your brake system cooler is to use shorter time braking
periods.  A short firm brake is much better than a long slow riding the brakes
technique.  The hotter the brake system the more chance you have of boiling
fluid and worse yet warping rotors.

My advice is to change your fluid yearly regardless of the car you are driving
or how often you use the car.  I change mine probably 2-4 times a year just
before track events.

On brake fluid bleeding/changing:  I purchased a hand operated vacuum pump kit,
Mighty Vac from Imparts for around $60.  This is an excellent kit that allows
you to accomplish the job with only one person.  No more making your wife sit
in the car to push the pedal for you.  This kit includes multiple adapter for
almost any type of car.  Imparts advertises in the Roundel.

==============================
Section 13.2:	How come most of the cars dont do  brake fluid change?

A:	(by Rick Kjeldsen: kjeldsen@domain.elided)

I can think of a couple of reasons for this:

 - I think BMW is unusual in how much technical info they put in the
owners manual.  On other cars I've owned this kind of info is in the
shop manual, not the owners manual.  The owners manual just says to have
"maintenance" done every so many miles, not what should be done.  Most
people who own appliance cars don't have the shop manual.

 - There is a trade-off between high temp performance and
suseptability to moisture in brake fluids.  The performance fluids
tend to have lower wet boiling points.  BMW's recomended fluid is
pretty good, it has a higher dry boiling point than most dealer fluids
I've looked at (with a few exceptions).  It may be theirs is also more
suseptable to moisture.

 - Even when brake fluid gets wet, it is fine for the average
driver on the road, there is just less saftey margin.  As a data
point, before she met me, my wife never changed her brake fluid, and
never had a problem.  But the first time I "soloed" in her Rx7 and
fooled around a little, I felt the brakes fade.  Another example: I
had my first car for 8 years and never changed the brake fluid.  The
only problem I had is toward the end, I lost the master and a couple
of slave cylinders to rust.

 - Another disadvantage of old fluid is poor pedel feel.  The buyers
of an expensive luxury/performance car are less likely to put up with
that than the typical appliance car buyer.

 - One of the selling points of Japanese cars is low maintenance.
That isn't accidental, they work hard at it.  Combine that with the
last couple of points.

==============================
Section 13.3:	What are silicone brake fluids?

A:	(by Richard Welty: welty@domain.elided)

well, silicone fluid can be an excellent choice for an older car
which is undergoing a complete brake system renovation and which will
not be seeing heavy service.

other than that, it's not necessarily a good idea, especially in cars
which are seeing service at driving schools such as those offered
by the bmw club.  also, it is a particularly bad idea in ABS systems
- - -- i'm not sure of the reasons, but i note that nearly every car with
ABS has an explicit warning against silicone fluids in the brake system.

first of all, silicone is difficult to pour cleanly; it will always
have a little air in it, and the pedal will always be a little spongey.

one of its supposed advantages is a higher dry boiling point; what is
not generally publicized is that unlike glycol based fluids,
silicone fluids become compressible independently of boiling, and at
a lower temperature than they boil at.  thus, the higher dry boiling
point is merely a technicality that doesn't actually do much in
practice.

one good feature of silicone fluids is that they don't trash paint, although
it is possible that if left on paint they may cause "fisheyes" when the
time comes to repaint the car (but i'm not sure on this point; it is merely
speculation based on what silicone based car "waxes" do when repaint time
comes around.)

while they do not absorb water, neither do they keep it out of the
brake lines; a well sealed brake system is still necessary as the water
will simply pool up and rot out the brake lines in a localized fashion
with silicone fluids.

they are _not_ compatible with DOT-3 and DOT-4 fluids; you must switch
completely if you switch at all.  since everybody i know at the track
uses Castrol LMA or other similar high quality fluid, somebody using
silicone fluids had better look to their own sources of supply (allison
and i once borrowed a bottle of LMA from Klaus the infamous Roundel
photographer at a Mid-Ohio track event once.  can't do that if you need
silicone fluid.)

there is some indication that DOT-5 fluids based on Glycol may appear
soon; if so, these would become the prefered fluids for street cars
at track events, i should think.

<<<<< 	(by Ben Thongsa: bthongsa@domain.elided)

Silicone brake fluid has the advantages over regular brake fluid of being
non-water absorbing, doesn't attack paint, and has a higher boiling point
than most regular brake fluids.

The disadvantages are that the fluid tends to trap tiny air bubbles more
easily, is more compressible than regular fluids, and doesn't absorb water.
Not absorbing water can be a disadvantage because if there is water trapped
in the system, it will settle out in the lowest points, causing rust or
possibly freezing.

I believe BMW says not to use silicone fluid in ABS-equipped cars.  This
is probably due to the compressibility of the fluid.  The ABS pump would
have to work harder when activated to keep pressure in the lines.

I personally would use good DOT 4 fluids in all but antique/show cars.
Silicone fluid would be acceptable for those because it wouldn't attack
the paint and if installed properly, would help keep the hydraulics
from rusting.

==============================
Section 13.5:	Tips to remember while using Mighty Vac

A:	(by Rick Kjeldsen: kjeldsen@domain.elided)

>I have this same unit and find it absolutely useless, due to air leakage around
>the bleeder nipple. Under all circumstances, I get a steady stream of bubbles,
>making "air in the brake lines" impossible to discern.

A couple of tips to help avoid this:
First use the pointy tool that goes inside the nipple hole, rather
than the one that is supposed to snap over it.  That one never snapps
tight enough, so you get bubbles.

Second, before you open (unscrew) the nipple, put a drop of oil on
the threads.  Works like a charm in stopping the air.  I've been doing
it for years with no evidence of the oil contaminating the brake
fluid, but just in case, I make sure to keep vacuum preasure applied
whenever the valve is open, so that any contamination will be
immediatly sucked out.  And, of course, wipe off the oil when you are
done so it doesn't attract dirt or get on the rotors/pads.