160k KM on the engine? You are right at the point where the belt should be done. Good luck getting that under warranty / service agreement, but I hope you can.
The "proper" procedure for that should include the idler pulleys for the timing belt, a new tensioner (b/c of the bearing in it, just like the idlers) and a water pump b/c it is a monumental pain to dig back in there for the water pump.

I don't know about any "lines" on the belt indicating wear, after 105k miles when I changed my own, the belt looked almost identical to the NEW one. I could still easily read the manufacturer's info on the back of the belt and the teeth were all laser-cut sharp.

I did not do the "suggested" changes on my own, b/c I did it myself and have the tools to do it with. Looking at the pulleys, they were all immaculately clean with no grease ejected, which is the first step in failure. Once the grease is ejected, the bearings start to howl, then fall apart rapidly after that. I just recently had an idler pulley on my Grand Cherokee fail out that exact way... After 250k miles on the engine! That was the first time ever for me, and NONE of my family vehicles has less than 100k on it except for my motorcycle. So I would feel safe with those idler bearings for a good while yet.

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TRAVELING CRD TECH. I come to you!
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Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

My Jeep has 201000km on it, before I bought it I asked if the belt had ever been done and he said he didnt know. I told him if I bought the warranty and I found out it was an original belt if they would replace it and he said they would so now its time to hold him to his word.

The belt still has the original Chrysler markings on it and it has a rust coloured line in the top of the belt opposite where the tooth is underneath.

I will have them do the water pump at the same time, even if i have to pay for the water pump portion of the service its still cheaper than the whole job.

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2006 Jeep Liberty Limited CRD
2000 Dodge Dakota Quad Cab 4x4 - 6BT Cummins Turbo Diesel
1998 Ski-Doo Mach Z 800 - Bring on the snow