This sound just recently started yesterday. Gets really loud when driving in 1st gear while letting off the clutch to accelerate. If put it in 4th gear at 20mph to accelerate it gets loud also.

Its the rattling sound. I checked exhaust and everthing is good there.

Motor is built with all new parts around 5K miles ago.

I haven't been WOT the car or driving it hard at all recently

 

Well dropping it off to a shop on Tuesday. So I will let everyone know...


I getting more popping out of my exhaust on shifts and my AFR's are not as stable before the sound started. Timing belt tensioner?

 

Lmk what you come up with when you find out.

 

Timing Belt tensioner was loose. thank goodness i got it checked out

The also discovered my crank seal was blown and oil pan gasket was bad. I knew I had an oil leak but it wasnt that bad. Damn the shop that built my motor.

 

Wow so I just picked it up from the mechanic. The sound is still there.


So I went to our local base hobby shop and started using a stethoscope to pinpoint the noise and i'll be damn I notice the serpentine belt tensioner pulley dancing around. I stuck the stethoscope to the arm of that pulley and rev'd. I got exactly what i was hearing on the outside of the car. The metallic rattling noise

Final diagnosis serpentine belt tensioner pulley/arm

all these thread have the same issue

https://www.evolutionm.net/forums/ev...ley-belts.html
https://www.evolutionm.net/forums/ev...ise-whine.html

 

Forgot to update this thread. The sound was the serpentine belt tensioner. The spring inside was making that popping sound when reving.

Replaced with new one and no more sound