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Tech Article

Audi C5 A6 Quattro 4.2 V8 Transmission Drain and Fill Plugs

Last Updated: 09/24/2017
Parts Group: Transmission oil pan
This article discusses the transmission oil pan for the Audi C5 A6 with the 4.2 V8, and the ZF 5HP-24A transmission, as made from 1999 to 2004, with the main focus being on the drain and fill plugs. If you're not here for the technical analysis but would rather buy a used unit from us, guaranteed to work and fit, then please select the link below: The information herein is based on my own car.

This transmission, according to Audi, needs no service over the lifetime of the car. According to ZF, the company that make the transmission used in this model Audi, it's prudent to service it every ten years. Servicing it means, at a superficial minimum, replacing the filter and the pan gasket. It also means draining away the old fluid and filling the transmission with fresh fluid.

As preventative maintenance, I also make a point of replacing the pressure regulator in the lower front housing in the valve body of the transmission. When worn, the pressure regulator can allow a pressure spike to blow out the rim of the A clutch drum, and then the transmission loses the first four forward gears and the transmission needs to be removed, stripped down, reassembled with fresh parts and re-installed ... which normally costs thousands of dollars.

In more-mundane transmissions, the dipstick is where we fill the transmission with fresh fluid. Not so in this case: there is no dispstick. We drain the transmission using the small drain plug, and we fill it using the large fill plug.

The plugs are towards the rear of the transmission ...

Here is a close-up:

Zoomed in more yet:

Both of these plugs require Allen key wrenches.
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