Despite appearances, I am making some
progress toward remedying the "weird noise" in the VW engine in
N891JF. I'm still not exactly sure whether it was excess play
in the cam's thrust bearing, or it was excessive gear lash
between crank gear and cam gear....because it had BOTH, and they
both sounded very similar. Replacing the cam bearings with a
new double thrust cam bearing (the old one was double thrust
also) reduced the end play to about .002", which is a big
improvement. Next was gear lash, and the cure for that is to
replace the cam gear. Sounds easy enough since the engine is
completely torn down anyway, but replacing the gear turned
problematic.
The gear was fastened to the camshaft with
three Allen button head bolts . I hate Allen headed bolts,
especially in a high torque application, because you're starting
out with a practically rounded hole, and the Allen wrench is
IFFY at best. I clamped the cam gear in a vise (with "soft
jaws") and the first bolt I tried to loosen refused to budge and
stripped right out. For the next two, I heated them up with a
torch to soften potential Loctite, and hit them with a half inch
air powered impact wrench. They reluctantly came out. I then
WELDED the impact wrench into the stripped bolt's hole, and
while it was still warm enough to loosen the Loctite, I hit it
with the impact wrench.....and it immediately broke the Allen
wrench! Now what? I can't drill the bolt out, because it's so
close to a cam lobe that I can't get the drill in there to
access it anyway. Then I looked up the strength of those
particular bolts, and they are M12.9! I could waste more time
breaking drill bits and getting frustrated, or I could just
order another camshaft with a new gear and be done with it. That
sounds easy, but apparently low end "stump pulling" VW Type 1
camshafts are apparently a thing of the past.
I spent a couple of hours trying to find a
cam like what I had and found nothing. Years ago, I spent a lot
of time researching cams in aircraft applications, and
determined the Eagle 2280 to be the best option. I found it in
a few places...."OUT OF STOCK" with no expected IN STOCK date.
I looked at other options, and finally found an Engle W100,
which is similar in profile, with only "ONE REMAINING" and
pounced on it. It should be here in a few days.
A good machinist could probably get that
broken bolt out somehow, but they're so busy in this town they
don't even answer the phone, and the wait time is equally
ridiculous. It never hurts to put a new cam and lifters in it
anyway. I'll get it back together eventually. Meanwhile, back
to the hangar to finish building a work bench addition.....using
TORX head screws!
--
Mark Langford
m...@n56ml.com
http://www.n56ml.com
Huntsville, AL
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