I found a break in a rubber hose at the rear of my V8's engine block. This hose originates from the air intake system. It splits off from the air filters housing and runs to a centrifugal pump, and then to the back of the engine where it connects to a metal Y split and continues. What is this sub system for?

 

What year is your car? I know the 2.7t made after 2001 has a brake breather hose plugged into the intake just before the Y pipe.

 

It's part of the pollution control system. You should replace it. You might get away with glueing it back together.

Bob

 

ahh I see, Thank you! must have been a lucky break to find this while removing a crushed fender! and I have a 2000 A6 4.2.

 

That happened to me too the fumes eventually eat the rubber. I used heater hose from advance auto store just bring in a sample for them to match it up. If you need to make a turn you can either use a piece of copper tubing or they have 90 degree fittings for heater hose at the auto store. it does not have to run exactly the same way just sort of out of the way and no dips for liquid to accumulate.
get some hose clamps too.

 

It has been about 2 weeks and 350 miles since the repair, and I have noticed that my car is much smoother on startup, and it seems that the gas milage has increased. Also, I have always had a check engine light because of the left bank catalytic converter's threshold is under spec. I know the cat is not functioning properly, but after clearing the codes the check engine light refuses to return. Could this broken hose have possibly caused my catalytic converter to over heat and wear out?

 

Well a solid check engine light means the emissions or pollution control system problem. If you fixed a hose that is part of the pollution control like bob said you should be golden. If might never have been the cat in the first place, just a hose that somehow is effecting its performance.