Q: Rattling noise upon starting and then louder rattling at idle if load is placed on engine such as A/C

asked by on October 11, 2016

My problem started as a rattle at idle when my A/C was on. Sometimes I get the rattle simply with fan on at idle or even just a bit with fan off, especially at a low-speed turn. There is also a rattling noise at start-up. These problems come and go to some extent, but have gotten worse - one step forward, two steps back. The noise at idle with the A/C on now is very loud - obviously I don't run it at idle.

I replaced the idler pulley and belt tensioner assembly - no help.

I am thinking perhaps the power steering or A/C pulley or the crank pulley or damper. More serious would be torque converter or flywheel itself, which I probably wouldn't do due to expense. I have had issues with power steering which I fix by occasionally draining fluid and adding the conditioner, which corrects the problem for perhaps 5000 miles.

Any ideas?.

My car has 222000 miles.
My car has an automatic transmission.

Hi there. Given your mileage and your maintenance of the idler pulley, your problem is likely worn/weak hydraulic lifters (or other valve train wear) or the timing gear set. Starting the engine briefly (less than 30 seconds) without the serpentine belt attached, will eliminate noises from all accessories if the problem is with one of them. I would recommend having the engine inspected in person by a professional so that the rattling noise can be diagnosed and properly corrected.

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