[T3] Knock Knock

[Daniel Nohejl]

Odd…..after this reply from Dave, I didn’t receive any of the 4 replies to my original message. Nor did I receive the three messages titled “Oil…”. Jessica found them because she uses the archive to read messages. So why have I not received the last 7 messages? I haven’t changed my settings or subscription or anything. 

In any case, the going theories with the motor noise are either valve train or connecting rod so it looks like the motor has to come out and the case will have to be split at some point and that I shouldn’t be driving the car right now. 

I’m less inclined to think it’s the cam itself as we were able to narrow the noise down to the #3 cylinder. If it was a cam lobe, we’d hear the noise on both sides and it’s clearly side and cylinder specific. I suppose it could be a lifter, but then why would unplugging the spark plug diminish the noise? That’s what seems to point towards a rod for me. 

Daniel


> On Sep 16, 2017, at 8:45 PM, Dave Hall <dave at hallvw.clara.co.uk> wrote:
> 
> 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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