Hi, My 2008 Altima has been running well until last winter. During cold engine temp I noticed rattling sounds from the engine. Sounds like the valves or the fuel injectors - esp when accelerating. The sound goes off gradually after 10-15 mins driving. Could this be the engine or the CVT transmission?
Thanks.

 

Rattling sound can be generated by almost any part of the car from the engine to the transmission. The cost associated to repair a rattle can vary between tightening a lose bolt to replacing the transmission. If a rattle is consistent with the engine speed it could be generated by an engine accessory like an alternator. If the rattle sound is related to vehicle speed the noise can be generated by a suspension component like a sway bar link. Interior rattles can be difficult to determine when the noise is coming from the internal workings of the dashboard. Other rattle sounds can be created when a system is engaged and then stops again when the system is switched off such as an air conditioner.