3 repair options from dealer, last is a new engine! Help.

[joiseyjeff]

I searched already. I have an 02 I35 with 133K. I started getting this sound like marbles in a small wood box coming from near the pulley area of the engine. Almost doesn't sound like it's coming from inside the engine, really hard to tell. The sound comes and goes very noticable at idle. It's not a ticking/valve/knock sound just image marbles in a wooden box. Senior tech at the dealership never heard anything like it. They went to work and gave me 3 options. #1, The timing belt tensioner looks like it has some play, replace that $500. #2, complete timing chain and related valve job $2700, #3 replace the engine. I had them do the tensioner and the sound did not go away. He dropped the small pan and didn't find any metal parts, very clean. Not sure what to do. Any ideas? Maybe try another dealership?

[AZhitman]

Definitely a 2nd and 3rd opinion.

Preferably from an independent shop... That's a durable motor, in a great car - No sense throwing out the baby with the bathwater.

Could be as simple as a bad accessory pulley.

[Q45tech]

I always ask customer if they have proof of 90 day oil changes. If they say 6 months I reply let's pull the valve covers to confirm. Because so many take that to mean once per year.As your 2002 [7years] equates to 20k per year, for 133k

The newer 3.5 is a bit more tempermental and demanding than the older 3.0

[joiseyjeff]

Update. Upon disassembly it looks as if my camshaft sprocket had collapsed. Not a cheap repair. Water pump, new chain, and some other parts are being replaced.

[maxnix]

Great. Hope they are careful and competent on reassembly.