Weird grinding/rumbling noise after the engine has warmed up

DALLASC18

MEMBER
2009 PONTIAC VIBE
2.4L
4 CYL
FWD
AUTOMATIC
70,000 MILES

My car is making a weird noise only after engine has warmed up to normal temperature. The noise is somewhat of a grinding noise but does not sound like actual grinding, more of a fast tapping or rumbling sound. It is hard to describe the noise. Only does the sound when I take off from a red light and only does it for a brief second. I put the car in drive, put one foot on the brake and rev the engine to about 1000 rpm's and it will make the same noise constantly. With only 70,000 miles, I have no clue what it could be other than the starter. Sometimes the starter will whine when a start the car on a cold day. I fear the spring may not be retracting all the way and the flywheel is hitting the teeth on the starter.

Friday, December 16th, 2016 AT 11:16 AM

1 Reply

CARADIODOC

MECHANIC
34,330 POSTS

Forget the starter. The drive gear sits on an over-running clutch that lets a running engine spin the gear without spinning the starter motor. A better suspect might be a collapsed engine mount that is letting it sit low on one side and the exhaust pipe is rubbing on a metal bracket or part of the body sheet metal. That will transmit engine noise into the passenger compartment. On some vehicles a broken engine mount can allow the crankshaft pulley to rub on the body when the engine shifts during acceleration or coasting.

There is a tool you might be able to borrow or rent from an auto parts store that borrows them called the "Chassis Ear". It is a set of six microphones, a switch box, and headphones. You clip the microphones to suspect points, then drive around while listening with the headphones. You can move the microphones around to zero in on the source of the noise. Be aware that many mechanics have never seen or even heard of this tool. Suspension and alignment mechanics use it to find rattles, squeaks, and other noises.

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Friday, December 16th, 2016 AT 12:21 PM