Touareg: 2004 V8
Join Date: Nov 2010
Location: Canada, Vancouver
Second Vehicle: Other
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Cavitation in the ATF ???
I was outside trying to get a better idea of where the sound is coming from and I am nearly 100% sure it's the transmission.
I am trying to figure out what work is done when the VB is changed. Obviously the last step is reinstalling the filter and an o-ring that has to be in straight.
If there were a leak in the pickup that allowed air to enter would this cause foaming and cavitation of the ATF? This is the sound I am trying to describe.
Imagine a drinking straw with a crack half way between your mouth and the top of the fluid. When you draw fluid up the straw with suction you also draw in air (venturi effect) and this causes the fluid to become full of bubbles. This also causes a hissing type of noise as the air is infused into the liquid.
Is this a plausible theory? Is there anywhere a valve body job can go wrong that would create this type of issue?
On a final note, I ran the rpms up a little in gear to heat up the fluid some then I checked the temperature on each side of the thermovalve on the ATF cooler to ensure that it was open. Both in and out hoses were equally hot to the touch so I am concluding that this valve is opening. While my hand was on the ATF rubber hose I could feel thumping like that of air bubbles running though the fluid. When I did try to add fluid with the engine running the fluid that came back out as overflow was covered in small bubbles. Is this normal?
Is this a possibility? Could the system be drawing air into the fluid before the pump?