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

asked by on

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.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Rattling noise upon starting and then louder rattling at idle if load is placed on engine such as A/C

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car is shaking while idling and leaking coolant

From what you have described it sounds like a coil or spark plug fault causing a misfire. With the coolant leak, the most common cause would be a coolant hose or the radiator leaking. The two may be caused by...

Q: Red lighting bolt came on while driving loss of performance now cant start car ive tried bout everything to start car etc throttle

The warning light refers to the electronic throttle control system. An advanced scanner would reveal some diagnostic clues, if any codes were stored. With regard to this model, reported fixes have included replacing the thermostat (the thermostat is electrically "linked"...

Q: 2013 vw 2.5 passata replace alt.having a problem with lower bolt in alt to lomg to remove hitting frame

I've never worked on one of these but the basics should be the similar to other cars. You will need to support the engine using a floor jack with something on it like a block of wood, then loosen the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.