Date: Mon, 10 Aug 1998 21:42:04 -0500
From: mulhouse_at_juno.com (Dave Mulhouse)
Subject: loose valve clearances
> While adjusting the valves, I could not perform the proper .012
>clearance with the #1 cylinder (foremost piston closest to radiator).
>This leads me to three possibilities:
>1) rocker arm is worn and needs replacement
>2) rocker shaft is distorted at end
>3) camshaft lobe is worn for #1 cylinder
> What do the gurus suggest? I would like to purchase a used
>rocker arm and see if replacing it will rid the car of the tapping noise
>I hear at idle. Otherwise, it runs smoothly as expected of an eta
>with excellent compression and power delivery.
> Joe Kramlinger
> Orlando, FL
I just went though a similar ordeal with the valves on my 84
318i. (I don't know if the rocker part #s are the same, but it is the
same type of setup.) After taking the valve cover off for the 3rd time,
I managed to find the source of the ticking on my M10 motor. A local BMW
guru (mechanic), suggested that I replace all the rocker arm eccentrics
to get rid of the tick. After a lot of miles, the eccentrics start to
develop flat spots which makes it difficult to adjust the valves to the
proper clearance. While the new eccentrics made it much easier to
adjust the valves, it was not the source of the tick. Consider replacing
these anyways, they are cheap.
After close inspection, I found that the tip of the valve stem
on one of the valves was slightly lower than the spring retainer. Thus,
when I stuck a feeler gauge in there I was actually measuring the
clearance between the rocker eccentric and the adjacent valve spring
retainer; (not the valve stem tip). You can sort of feel this with the
feeler gauge. When you move the edge of the feeler past the tip of the
valve stem you can feel the feeler gauge bind up on the spring retainer.
It's hard to describe, but on a normal valve you should *feel* the same
valve clearence no matter what part of the feeler gauge is over the valve
stem.) Because of this problem, it was impossible to measure the
clearance between the rocker and the valve stem. To adjust the short
valve, I first carefully adjusted all the other valves. Next, I measured
the clearance between the cam and the rocker arms on the previously
adjusted valves. Next, I transferred this new clearance to the valve
with the short stem. I did it this way because the clearance between the
cam and the rocker feels different than the clearance between the rocker
and the valve. Now the only ticks I hear are from the injectors...
Hope this helps, and good luck.
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