My 2004 g35X with 167k started running rough a couple of days ago. I took it to my local shop, and they told me that it had "jumped two teeth" and would cost $2500 to replace timing chain and tensioners.

I asked if they had visually inspected the chain and sprocket to verify that it was off, they said diagnosis was just based on codes. I did not get the codes, but can if I call back tomorrow.

I've got a couple questions:

- Is this a reliable way to verify what actually went wrong?

- How common is this issue?

- Should I start by replacing the cam sensors?

- If it has in fact jumped, is there any way to get it back in timing without the full replacement so I can just dump the thing?

This car has been great, and provided 70k of service, but I'm just not willing to spend $2500 on a car worth maybe $4k.


Thanks in advance.

 

If it jumped time you have to replace the chains the stretched! And replace tensioners. They usually make a slapping noise from front.of the engine. You are lucky it didnt break then you would be replacing the topend or buying a crate motor!

 

I'm no professional but it would seem fairly hard for it to jump 2 whole teeth and if it did jump 2 teeth it probably would run very poorly or not at all and could have damaged the valves.

Does the car start? If possible have someone start your car while you listen to the engine. Any Rattling or weird noises upon start up? Also listen to it while running. Any noises or rattles or metallic knocking or grinding sounds? If you hear weird noises, fix asap..

Doing anything with the timing chain is going to require you to pull the front cover and if you're in there, do it all or at least verify everything is within spec. Timing chain replacement should be a weekend job if you're mechanically inclined. A day if you're good.

I would verify the code...

 

If there are codes, they should be coming back. Head over to Autozone and have them read along with "pending codes"

Jumped timing chain is tough to do. I've had belt jump, in which the car runs VERY lean and lacks power.