[T3] Vibrational Sound

[Jim Adney]

On 11 Mar 2014 at 20:05, Gregory Cox wrote:

> I´ve a couple of troubling issues with my beloved ´73 FI. First, it is
> making a strange vibrational sound - I´ve attached a link to an audio
> recording of the sound. Any ideas? 

Can you get the car to make this sound when it is not moving? If so, 
go to the engine and listen while you work the throttle and listen.

> https://www.dropbox.com/s/ifhfexan44m5jvy/G2%20Vibrational%20Sound.wav

I'm not sure that I can make out the sound from your sound file, but 
one thing to check for would be a loose fan housing. Look at the 
engine and grab the "horns" on each side of the fan housing, that's 
to the rear of the engine (rear is rear.) Try to twist it side to 
side. If you can get that part to move with respect to the main part 
of the engine, your fan housing is coming loose. If so, you need to 
fix it quickly, before expensive damage is done. Let us know if this 
is the problem; if so, we'll tell you what you have to do.

It's also possible that this is from your rebuilt tranny. I suspect 
that almost no one bothers to actually rebuild them correctly; it's 
just way to involved and takes too much time. Consequently, the ring 
& pinion gears often don't get mated correctly and will make noise. 
If this noise appeared as soon as the freeway flyer was installed 
then that's a possibility.

If you've reusing an older stock style muffler, then this could also 
be just a loose heat shield.

> Second, on an FI, what mimics a stuck choke - sluggish, no power,
> especially on a grade, doubled gas consumption? New FI harness at
> engine rebuild (balanced, blueprinted @ approx. 500 miles ago) and a
> Freeway Flyer.  

Either a stuck distributor mechanical advance or a worn out voltage 
regulator. Both are common. 

For the distributor, remove the cap and twist the rotor CW. There 
should be a little bit of free play then it should twist smoothly 
against some spring force until it runs against a stop. When you 
release it, it should snap back smartly. If it feels sticky, remove 
the rotor and put 2 drops of oil down the hole in the top of the 
shaft and let it soak in. If it is stuck, send the distributor to me 
to be rebuilt.

For the VR, check the battery voltage with the engine still running 
at medium rpm after a warmup drive. It should measure 14.1 - 14.4 V. 
It helps to have a second person to do this measurement. If it is 
below 13.5 V replace the VR with a Bosch 30-019. I have them if you 
can't find one locally.  

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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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