nick n

What past audi's were chain (not just cams) driven?

Žob

none...all had timing belts

nick n

Chains usually last longer and can be 'pushed' harder, before servicing.

Maybe a belt is more cost effective for audi?

The euro S4 makes a good enough amount of power to deserve a chain imo.

Lucas_Gchips

They run a cam Belt from crank to Exhaust cam
Then the run a Cam chain to connect Exhaust & Intake Cams.
So there are two separate tensioners.
Cam Belts are not the only item that is prone to failure, the tensioners may fail also.
The Rear Cam Chain tensioner is very prone to wear along the Chain guides.

nick n

So tensioner failure is definatly not as disasterous as a belt snap that would throw off the timing and cause the valves to hit.

If the rear cam chain fails (or pops off the teeth/guides) then what amount of damage should expected?

TIA

Žob

BMW offers chains...they still recommend similair service intervals on their chains. They stretch, etc, just like a belt. The cam chain (not the timing chain) is essentially a no maitenance item in an Audi. Until one breaks (however unlikely) I will not worry about. But stay on top of those timing belts!

Lucas_Gchips

The rear Cam Chain (not Belt) is actually not a real good design.
The Chain runs along plastic runners.
These plastic runners wear.
Once these runners wear through, the chain will then encounter a PIN.
Hmm what happens then....Jam and chain Break.
You will be also up for 1 set of intake valves, and that is as long as the cam belt does not break, then you will be up for a set of exhaust valves.
Porsche engines that use a cam chain tensioner actually use sprokets as the guides, but the 1.8T engine does not have the room to impelement this better setup, and thats why the Plastice runners are there.
Yes Keep on EYe on these are well as any other Part..

JayP

You thought wrong-- tensioner failure lets the belt jump teeth and will destroy heads.

nick n

Are you talking about the cam chain or refering to the timing belt?

It sounds like you're saying that the cam chain tensioner fails before the timing belt in the 1.8T. Confirm?

JayP

Timing belt- if the TB tensioners fails, its really bad.