[T3] ? Mystery of the Clacking Valves ?
Keith Park
topnotch at nycap.rr.com
Wed May 11 17:34:50 PDT 2011
The only thing I might mention is that with a 1776 you most certainly have a
non-stock cam in it, so you would also have dual valve springs that require
steel pushrods, if the originals were aluminum that would explain the bend.
Secondly, when the installed the new pushrods did they cut them to the exact
same length as the ones that were in it? If not that could wreak havoc with
the valve train geometry and cause quick wear to the guides and seats in an
extreme case. With a 1776, you wont be running stock geometry or stock
length pushrods.
Keith
Top Notch Restorations
topnotch at nycap.rr.com
http://www.a383ina68.addr.com/radiorest/main.htm
71 Squareback "Hothe"
65 Notchback "El Baja Rojo"
65 Squareback "Eggcrate"
87 golf "Winterat"
93 RX7 "Redstur"
-----Original Message-----
From: type3-vwtype3.org-bounces at lists.vwtype3.org
[mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of David
Yaghoubian
Sent: Wednesday, May 11, 2011 8:13 PM
To: type3 at vwtype3.org
Subject: [T3] ? Mystery of the Clacking Valves ?
If you've got one of those Sherlock Holmes pipes, spark it up... :)
Keeping this as succinct as possible to start, my super clean,
perfectly running 1776 (@~35K miles) developed a bad pushrod tube
leak in the outside tube for the #3 cyl last week. It never skipped a
beat that I noticed, but was spraying oil, so I had to get it fixed
pronto since it's my daily driver. Not having time to do the job
myself I took it to my local shop... highly trusted folks who have
been working on VWs since the mid-70s and who have routinely done me
and my square right over the past decade. What they found was that
the pushrod in the leaking tube was bowed/bent (!) and had been
rubbing on the inside of the tube, causing the leak. They pulled the
engine and removed the head to see if there was any damage to the
valve or seat that might have caused the pushrod to bend, but the
head looked perfect. So they put the head back on with a new tube to
replace the leaking one, installed a new set of pushrods and lash
caps all around, adjusted all valves, drove it around, then adjusted
the valves once again when it was cold. The mystery of the bent #3
pushrod remained... I have it here as a souvenir to ponder.
Soooo... I drive home, and then to work and back the next day (~30
miles total) noticing that the idle keeps creeping up...eventually to
around 1500rpm at idle. The valves sounded loud as hell when I went
back to check the engine, and I could tell something was way off due
to abnormal fumes/smell. So I waited until the next morning until
they were dead cold, and went to do a valve adjustment. I was shocked
to find all of the valves more out of adjustment than I had ever seen
on a VW engine.... I'm talking about 1/8/ to1/4 in. gaps...I don't
have a gauge in the kit to span that canyon!!! The rocker arms were
tight, and nothing looked broken/missing anywhere. So I called up the
shop owner, who was about as surprised as I was to hear this, and
didn't really have an explanation beyond that the rods had possibly
shrunk or reseated somehow, but basically concluded he wasn't sure
how that could happen. We decided I would finish doing the
adjustment, and see what happened after some more driving.
Sooooooo.... I did the valve adjustment all around (.004 as usual)
and did another round trip to work on the freeway (~20 miles total).
The next morning I check the valves dead cold, and am amazed to find
that after my easy freeway commute they were all way out of
adjustment again. The outside #1 valve was so far out of adjustment I
had to use up almost all of the remaining thread on the adjustment
screw to get it back to .004. The other valves weren't nearly as bad
as this one, but were all at around .013, which is still insanely
loose... after only a 20 mile drive! I called up the shop with the
news and they said to definitely bring it back in asap so they could
determine what the heck was going on.
Which brings us to today. They pulled the new rods out (an EMPI set)
and nothing looked bent/broken or out of the normal. They replaced
the EMPI set with a new set of Scat rods, which rumor has it are
superior steel than the EMPIs. (?) Before putting the new Scat rods
in they used a tiny camera to look at the lifters, and aside from
what was described as a stripe of what looked like rust on that
outside #3 cyl, nothing looked out of the ordinary, and the engine
oil is still clean-clean. They test drove it on the freeway today,
and are going to do the valves again before I pick it up tomorrow
morning to give it another shot.
Hence, the mystery of the clacking valves. Does anyone have any
explanation(s) for how the above could transpire? To start, I am
stumped as to how the #3 rod was originally bent/bowed. More bizarre
is the radical change in valve clearance/adjustment on all cyls, and
especially the #1, which used up a full adjustment screw's worth of
thread in less than 50 miles. Aside from the cam lobe getting ground
down severely (which one would expect to see in the oil, no?) I can't
for the life of me understand the physics/geometry behind this. Where
did that ~1/2 inch on #1 disappear to?! Ultimately I'm going to pick
it up tomorrow, drive it, and check the valves again (and again) but
since this engine has thus far been 110% reliable and never seen any
abuse/trauma I'm just very curious, and more than a bit concerned.
Thanks to any and all who might be able to sleuth this and shed light!
Dave Y.
68 Square
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