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>From: lethin@ai.mit.edu (Richard A. Lethin)
Date: Fri, 15 Oct 93 12:15:03 EDT
To: bmw@balltown.cma.com
Subject: Valve Adjustments
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?
2) The stiff wire tool: can I use a coat hanger?
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.
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?
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?
6) Any tips on different clearances I might want? '86 325
Any other useful tips
-- Rich
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Date: Fri, 15 Oct 93 10:54:16 MST
>From: Justin Seiferth
Subject: Re: Valve Adjustments
To: lethin@ai.mit.edu (Richard A. Lethin)
X-Mailer: LeeMail 2.0
>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?
It's easier to pull the distributer cap and use the rotor to determine where the
crankshaft is. Just point the rotor at the cylinder to be adjusted and adjust
the cylinders in firing order. It's also easier to use the starter motor to
turn the crankshaft. Just disconnect the line from the key and use a remote
button (available at most automotive places) to turn the crank. Make sure you
do above first!
>
>2) The stiff wire tool: can I use a coat hanger?
I do.
>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?
There's a gap. You'll feel it when you do it. 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.
>
>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?
>
I set my valves looser than spec because it seems to help idle and improve
performance here in the desert. Then again, I have a 3.5 not a 2.5
C. Justin Seiferth
Phillips Laboratory
(505) 846-0561 (V)
(505) 846-0473 (F)
seiferth@lyra.plk.af.mil
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Date: Fri, 15 Oct 93 10:28:01 PDT
>From: Peter LaPine dtn:381-6007 ZKO3-4/T23
To: lethin@ai.mit.edu
Apparently-To: lethin@ai.mit.edu
Subject: FWD: Valve Adjustments
>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?
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?
You could... 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...
>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.
You're gonna find it *real* tough to turn an engine over with the
plugs in... Remove them to disallow engine compression - i.e.
let the pistons move and expell the cylinder air through the
plug hole.
>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?
Yes.
>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?
The engine is designed to have the valve clreaances made when the engine
is cold - i.e. sat overnight. As things heat up. they expand (!) -
remember, water is the exception... A certain tolerance is required
between the valve stem and the rocker arm for to allow the valves to
close completely as well as to open completely enough.
If the intake valves don't open long enough, you lose getting all your
fuel/air mixture. Same for exhaust valves - with getting rid of all
of the exhaust. Too little clearance and they don't shut completely...
too much clearance and they don't open completely...
You'll find after a while you'll hear your engine getting a little
noisy - and it's time for another valve adjustment. You'll also
find after a while, that some (most?) of the valves don't need any
adjustment, and it's often the same ones which have gotten tight (I
think those are usually the exhaust) and some have gotten loose (intake
I think - maybe it's the other way around - whatever...)
>6) Any tips on different clearances I might want? '86 325
I've only heard of people fooling around with 535i valve clearences
(+0.001). That is, 0.013 instead of 0.012. I haven't heard of any
recommendations for a 3-series.
>Any other useful tips
Take your time and do it right. Allow yourself a couple of hours if
this is going to be your first time...
>-- Rich
-- Peter (so much for Zen and the art of valve adjustment...)
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X-Station-Sent-From: eve.bellcore.com
X-Sender: dje@eve.bellcore.com
Date: Fri, 15 Oct 1993 14:25:02 -0700
To: lethin@ai.mit.edu (Richard A. Lethin), bmw@magnus.acs.ohio-state.edu
>From: dje@mail.bellcore.com (Don Eilenberger)
Subject: LONG: Re: Valve Adjustments
X-Mailer:
>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:
Rich... here are the answers:
>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).
>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.
>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
Let some 2.5l owners answer this for you.
>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. 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.
Lots of luck, and let us know how it works out!
Don Eilenberger
Bellcore
331 Newman Springs Rd.
Red Bank, NJ 07701
Voice: 908-758-3167
FAX: 908-758-3166
EMAIL: dje@mail.bellcore.com