[T3] Knock Knock

Sean Bartnik sjbartnik at mac.com
Sat Sep 16 18:01:03 PDT 2017


Actually it does change as the pressure comes up, it gets quieter when engine speed is increased. 

-Sean

> On Sep 16, 2017, at 8:52 PM, Keith Park <topnotch at nycap.rr.com> wrote:
> 
> that sounds like valve train, it doesnt change as the oil pressure comes up
> so it isnt a pressure fed bearing.
> 
> Keith
> 
> 
> Topnotch Restorations
> topnotch at nycap.rr.com
> http://www.a383ina68.addr.com/radiorest/main.htm
> 71 Squareback  "Hothe"
> 65 Notchback  "El Baja Rojo"
> 93 RX7  "Redstur"
> 87 Golf  "Winterat" RIP
> 01 Sentra SE "Boremobile"
> 
> 
> -----Original Message-----
> From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
> On Behalf Of Sean Bartnik
> Sent: Saturday, September 16, 2017 7:14 PM
> To: type3 at vwtype3.org
> Subject: Re: [T3] Knock Knock
> 
> Just to add my impression since the character of the noise doesn't always
> come across in video (though I think this one does a good job).
> 
> It's a very metallic hammering type sound.  Sounds deep; not like valve
> noise.
> 
> 
>> On Sep 16, 2017, at 6:51 PM, Daniel Nohejl <d.nohejl at gmail.com> wrote:
>> 
>> 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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