Timing Chain Rattle - 2003 Murano

[acerun]

We started to hear intermittent rattling from the engine on our 2003 Murano with 80k miles. I took it in for service, they said that the rattle was coming from the timing chain area and that it was most likely a problem with the timing variable cam sprockets. They recommended a hot oil flush first to try and avoid going in for a mechanical repair. I have heard mixed reviews of whether hot oil flushes really do anything. The noise is gone for now but if it comes back they are quoting close to $3k as a high level estimate. They say it is from poor oil change history but I get them every 3k to 5k.

Has anyone had a experience like this or needed to complete this repair?

Is going in to replace the variable cam sprockets the good first mechanical approach? I believe they quoted 9 hours of labor just to get in there and then just north of $500 for each cam sprocket.

[CPS]

If they are going in to do that, you might as well go ahead and get all new chains and tensioners and a water pump while you're at it. The chains and tensioners will be off to do this repair, so that is free labor (so to speak). The water pump isn't much more work either, so that will be inexpensive also.

It is a big job, and while it can be done in the vehicle, it is so much easier to drop the cradle and do it with the engine out. Either way it's a lot of work, and 9 hours sounds conservative to me.

I have no idea what a hot oil flush is, but down here we offer an engine flush in a situation where you are trying to save a motor without breaking it down. 9 out of 10 times it doesn't work, but the one time it does, you have saved the customer a fortune.