[A8] Crankcase breather hose replacement

Martin Karo martin.karo at verizon.net
Sat Oct 6 16:02:40 PDT 2007

I had posted this on AudiWorld D2 forum, but thought if someone here didn't read that, this might be of interest.  

My crankcase breather hoses (at the back of the motor) turned to gum, and I tore the driver-side one while replacing the valve cover gasket. I'll be damned if I'm going to pay the $132 Audi charges for a simple foot-long breather hose, no matter how fancy the moulded shape, so I looked for a substitute.

Abbott Rubber in Elk Grove Village, IL sells suitable standard fuel line hose, thicker and tougher than the Audi original; the 3/4 inch size is perfect for the rear breather hose application. It's less than three dollars per foot, and two feet is plenty for each hose.


The OEM hose hugs the back of the motor and has a fancy moulded flange for the rear valve cover connection. To use normal hose, after much experimentation I concluded that the best path was to connect it at the bottom, arch it over the heater hoses and rearwards through the vacuum hose loop mess, then bring it around and straight forward to the valve cover, going under the heater hoses at the top. It's easier to see when the car is in front of you. Pep Boys sells a wire spiral apparatus that enables you to bend a straight hose fairly sharply without kinking it; not necessary, but nice.

Know that this job is a truly painful bloody b!tch due to the fact there is practically zero clearance at the back of the motor, plus a maze of vacuum and heater hoses, plus lots of sharp edges. Don't even bother with latex gloves, they'll be ripped to shreds in seconds. To gain a few precious inches of clearance I removed the cruise control linkage. Removing the vacuum and heater hoses would probably help more, and if I ever have to replace that hose again I will do that.

The original clamp at the bottom of the original hose is a one-use strap affair. To secure the new hose, I used a worm clamp, reaching down from the top with an 8mm box end 12 point wrench, moving the clamp screw/bolt a few degrees, then repositioning it to do a few more degrees, something on the order of forty times. DO YOURSELF A HUGE FAVOR AND USE A SPRING CLAMP. It doesn't have to be very strong, and the spring can be positioned from the top relatively easily.  Someone else suggested using a big zip tie, and that would probably work too.

'98 A8Q 90k

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