Hi all, looking for help on a noise issue that has me stumped after extensive diagnosis. I’m hoping someone has heard this before.

Symptom:
Regular metallic grinding/raking noise that appears as soon as engine RPM exceeds ~1200 RPM. Not a pop, bang, or knock — sounds like a mechanical part rubbing constantly, regular and continuous. The noise:
Appeared overnight (started cold, ran fine at idle for 5 seconds, then noise kicked in as soon as I throttled up)
• Same noise with original starter, used starter (Hitachi S114-254DAM), and brand new starter
• Identical whether clutch is engaged or disengaged at 1300 RPM
• Last time it occurred, I let the RPM drop back to idle and the noise continued for ~3 seconds while RPM was falling — sounds like a mechanical part still spinning by inertia
• Recent context: aluminum radiator installed ~1 month before noise appeared (mounted lower than stock to fit thicker core)`
I ve tested the AC bearing, and it s fine…
Any clue ?
Thanks

Sounds like a pulley bearing. Does your’e ac have an idler pulley. Need more pics of the front of the motor. Left,Right, and top. Could be the water pump as well. On the water pump the seal normally fails before the bearing allowing coolant to reach the bearing. Alternator bearing as well.

Hey

In the video i took out the AC belt so it s not involved in the noise.

Next try will be without Alternator belt to see if thé Sound disapear

I ll take photos tomorrow

Thanks

Just watched the video. Not sure that Yarb did (no offense intended), that noise is terrible.

Seems like whatever it is must have some mass, to keep spinning after the engine is shut off (from your title). Can't tell if the engine is spinning though in the video, although it seems to be shaking. Also don't know if you have your foot depressing the clutch pedal or not.

It might be the input shaft to the transmission spinning transmission parts. Try the test with no belts and your foot depressing the clutch pedal, with the transmission in gear. That will stop any of the transmission parts from spinning.

Another high mass item is the crankshaft damper. The belt-off test will tell something.

On the video I did not depress the clutch

I did test depressing the clutch before starting the motor (but with no gear engaged) and same noise ,(

Fan or fan clutch maybe. You probably removed it for the radiator. The fan blades could cause some serious vibrations. Check the bolts. The no-belt test should be telling.

6 hours ago, Zed Head said:

Just watched the video. Not sure that Yarb did (no offense intended), that noise is terrible.

Seems like whatever it is must have some mass, to keep spinning after the engine is shut off (from your title). Can't tell if the engine is spinning though in the video, although it seems to be shaking. Also don't know if you have your foot depressing the clutch pedal or not.

It might be the input shaft to the transmission spinning transmission parts. Try the test with no belts and your foot depressing the clutch pedal, with the transmission in gear. That will stop any of the transmission parts from spinning.

My hearing is just fine, I’ve found the art of troubleshooting involves, What was the last variable that was manipulated or replaced. From there check the obvious external moving parts. Once those have been nullified continue to dig deeper one step at a time. Going down rabbit holes is not productive IMO.

I have test w.o the alternator belt and bingo, no more noise !

When i move the pulley it s a Little bit rough and when moving up and down I have a small noise (see the end or the video)

The water pump seems fluid and noiseless.

Guess I have m’y suspect ?

That’s awesome, Glad you found the problem.

5 hours ago, Nagual said:

Guess I have m’y suspect ?

Suspect maybe, but no clear cause. Not clear how all of the noise in the first video would be caused by that. Also never really answered the question about "engine off" noise. Why would the alternator keep spinning if the engine was not? Just trying to make sense of the words you wrote.

Making progress though.

"...persists after killing engine..."

If the belt is off that means the fan is not spinning. May have an issue with the fan or water pump. @Zed Head brought up a good point. You are actually deleting 4 items