[T3] Knock Knock

[Dave Hall]

That sounds just like the worn cam I had on my 30hp Beetle engine. On that
the push-rods could be taken out as a single piece with the cam followers,
and one cam had worn the followers concave, through to the internal oilways.
If it's a worn cam, and/or follower, you'll have to split the case to fix
it.

I hope I'm wrong!

Dave
UK VW Type 3&4 Club
===================

-----Original Message-----
From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
On Behalf Of Daniel Nohejl
Sent: 16 September 2017 23:51
To: type3 at vwtype3.org
Subject: [T3] Knock Knock

Over the last few weeks, we've been trying to diagnose a noise....

In Madison, I thought I noticed what sounded like a loose valve. A day or so
later, we discovered that the connection between our heater box and muffler
was loose. We tightened it and applied some muffler repair and the noise
vanished. Now, we have a new louder noise that has emerged over the last few
weeks. It's been hard to diagnose as the noise is generally loudest at cold
start and for the 10 or 15 seconds the engine is running before the high
idle kicks in. To properly diagnose, I had to pinch off the AAR hose at the
air cleaner so I could get a low idle for a longer period. I also required
the assistance of Sean, whose ear has proven indispensable more than once.
Anyway, here are the other general characteristics of the noise:

1. The noise is loudest at idle
2. Above idle, it sounds like a loose valve.
3. While cruising, it can barely be heard, even when driving next to a
concrete divider on the highway.
4. After letting off the gas, the noise doesn't return until just above
idle. It definitely doesn't start up right after getting off the throttle.
5. It's clearly coming from the 3/4 side of the motor.
6. All valves are correctly set, there's no excessive side play (solid
rocker shafts), the springs are fine, etc. I've run the motor several times
with the valve cover off and everything looks right. 
7. After unplugging the spark plug wires at #3 and #4, it's clear that the
issue is at #3. With the #3 wire unplugged, the noise diminishes by a good
80%

Here's a video (credit Sean) that does a great job of capturing the noise

https://youtu.be/sxs1yrFLPl0

I know what all of this suggests, but I'm curious if what I'm describing
rings any other bells for anyone. Or, if we know what it is, can it be fixed
without splitting the case????

Thanks, 

Daniel


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