Metal Scraping Noise at Idle

[Venus]

Friend of mine brought his 87 GN over last night and wanted me to listen to a strange noise his car makes. Car is mostly stock and only has around 35k miles on it. Car can be hot or Cold, at normal idle in park the motor sounds fine but if you crack the throttle to rev the engine up above probably 2k rpms or so and then let go of the throttle, you can hear what sounds like a metal to metal scraping type noise briefly. It will also make the noise while driving the car if you step on the gas and increase the RPMs. It has me stumped and I guess the noise has just started. I checked the exhaust and heat shields and nothing seemed loose. Noise doesn't last long and almost has me thinking it only does it when maybe something is expanding as the rpms increase and it's rubbing somewhere that causes the sound. Car is not a POS and is not raced as its just mainly cruised around. Any ideas would be appreciated.

Thanks,
B-

 

[robzombie]

If not a pulley noise, it could be the flex plate or converter rubbing at the brief rpm you describe. They call it a flex plate for a reason as it moves in and out with rpm and load.

If you could describe the noise or area it's coming from it might help someone give a better answer.

 

[Venus]

Would a crank sensor rubbing cause a similar sound? Car doesn't have any drive ability issues though.

 

[robzombie]

I doubt it but you could check for rubbing on the sensor and the ring being out of round.

 

[needforspeed150]

If not a pulley noise, it could be the flex plate or converter rubbing at the brief rpm you describe. They call it a flex plate for a reason as it moves in and out with rpm and load.

If you could describe the noise or area it's coming from it might help someone give a better answer.

I would check the flex plate to converter bolts. I had a noise and all of them were loose.

 

[1986 Buick GX1]

Mine made a scraping sort of noise after installing a gear reduction starter.
It ended up being the torque converter cover was on the wrong side of the lip alowing the cover to contact the flexplate at certain rpm's.

 

[salvageV6]

Intercooler shroud vibrating on swaybar?

 

[MAK507]

Could you record a video and upload to YouTube just to hear it?


Sent from my iPhone using Tapatalk

 

[mikes86ttop]

Crank sensor...Mike

 

[drturbo69]

Some had a/c compressor mounting bolt missing from factory? Apply pressure to belt tensioner see if a difference?

 

[SHADOWII]

Had a spot weld break on the ds header shield by #5 cyl. exhaust port so I removed it. A few months later the header cracked and it was easy to find!My first choice would be the converter/flex plate cover, around the starter area as previously stated.

 

[nickygn23]

My turbo shield came loose and made a scraping sound. I guess it was vibrating on my downpipe. Check that

 

[Dhos1]

Agree on the flexplate/ converter

 

[Chris McDade]

Could be a turbo going bad? I would turn by hand and check for play.

 

[earlbrown]

If it only does it coming down from revs I'd listen at the 'timing chain hitting the timing cover'' area and then go from there.

 

[Bescurred]

Does it give you an indication if its coming front of motor? Back? Low? High??

 

[Venus]

So first of all, thanks everyone for the feedback and replies, it is much appreciated. It seems replacing the crank sensor and bracket fixed the issue. I did notice the crank sensor was loose and the crank pulley showed signs of the crank sensor rubbing on it. Seems odd as the car never had any drivability issues and I would've never thought that would cause the issue. Maybe I'm wrong and it's a coincidence but he is supposed to keep me posted.

 

[mikes86ttop]

OTE="Venus, post: 3706252, member: 43912"]So first of all, thanks everyone for the feedback and replies, it is much appreciated. It seems replacing the crank sensor and bracket fixed the issue. I did notice the crank sensor was loose and the crank pulley showed signs of the crank sensor rubbing on it. Seems odd as the car never had any drivability issues and I would've never thought that would cause the issue. Maybe I'm wrong and it's a coincidence but he is supposed to keep me posted.[/QUOTE]
I had the same problem, no issues just the noise...