RE: E28 valve noise

["Karl Zemlin" <karl@xxxxxxxxxx>]

I wrote up a response last night, but my email was hosed so I couldn't send
it.  This reply is much better than what I wrote.  The only thing I don't
see mention of here is cam wear.  If the oil bar bolts over the cam come
loose you can lose lubrication at the outer ends of the cam.  While you're
adjusting the valves, check the cam for flat spots on the lobes at the outer
extremes.  Chances are it's fine and valve adjustment will take care of it.

When you do the valve adjustment, lean to the tight side.  With my first BMW
I tried to aim for very light contact on the feeler gauge when adjusting the
valves.  When I attended my first club tech session, everyone there turned
and looked at my car when I drove up.  When I stepped out they all said, in
unison, "You need your valves adjusted".  When the mechanic was adjusting
them he used a feeler gauge at the low end of the clearance spec (which I
don't recall ottomh) and had to pull and wiggle a little to get it out from
under the rocker arm after the eccentric was locked.  I was amazed at the
difference when he was finished!

Good luck!

- -----Original Message-----
From: owner-bmw@domain.elided [mailto:owner-bmw@domain.elided]On Behalf Of
jkerouac@domain.elided
Sent: Friday, January 04, 2002 4:27 AM
To: bmw digest; Carl Runion
Subject: re: E28 valve noise


re: E28 Valve Noise:
    Oil pressure checks are unnecessary, that would be barking up the
wrong tree.  If there were oil pressure problems the you will likely see
the oil light glow dimly at idle and go out about 1000 to 1500 rpm.  The
fix for that is either to replace your oil pump if the pump is weak, or
to replace the oil pump chain, crankshaft gear, and then shim the pump
properly so the chain is snug.  Generally, low oil pressure will not
cause valve taps, valve wear does.
    I had a 533 that was running great at 225k miles when I sold the
car, and did need to replace the oil around 200k miles.  There was no
tap problem, just the oil light coming on as I described above.
If you have valve noise, the first thing on the old big block motors is
to adjust the valves.
    In doing that you may find too much wear on the rocker arm
eccentrics to get the correct clearance.  If that is the case replace
the eccentrics.  Be sure to use a new bolt, nut, and washer with each
new eccentric.
    Contact a digest advertiser to obtain these parts.
    Also be sure to replace the valve cover gasket and do not
overtighten the valve cover nuts.  Its amazing how seemingly loose the
proper torque for a leak free valve cover is compared to how over tight
most gas station gorillas would tighten them.
    You might also be getting some tick from the chain and/or gear if
the wear is sufficient.  Therefore if you want to get more involved, as
long as you're in there already, if your valves are this worn its very
likely the timing chain is stretched and the cam gear is well worn.
With an engine as worn as yours by replacing the chain and gear you can
regain some idle smoothness and restore some lost low end torque.
Changing them is just another few bolts to take off the front cover, and
connecting the new timing chain to the master link of the old one to
fish it around in place.  Always tie the chain off with hanger or safety
wire just to be absolutely sure there is no chance you could drop the
chain down in the engine, that would put you in deep doo doo, and I
don't mean your dirty oil.
    Another suggestion for a high mileage motor would be to take a
compression check too, only after you have adjusted the valves.
Good Luck,
"jk




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