Strange rattle sound only at a certain RPM

[TType85]

I have a annoying issue i'm trying to track down. Today was the first day I was able to take my car to work and get a few miles on it since I had the engine done in Nov/Dec. It ran great except one thing.

In gear, moving, at 2000-2150 RPM ONLY it makes a metallic rattling sound. It is a rapid vibration sound. Below 2000 RPM and above 2150 RPM according to the scanmaster it does not make the sound. I can make it do it sneaking up to the RPM range or coming back down.

It has had this noise before the motor was rebuilt. it has done it with a stock DP/Cat (what I have on now to smog the car), a THDP/gutted cat, multiple different turbos, water pumps and power steering pumps. Only the Alt and idler pully have not be changed. It's not the IC, the car had a FMIC on it and now a V4 and still has the same noise.

I haven't been able to find any loose heat shields or anything like that. I have a TT chip so I don't think the EGR is being used but all of that is hooked up. (there was a thread I found searching that people had EGR's make strange noises).

Any ideas?

 

[Reggie West]

Torque converter bolts ?

 

[NorEaster]

I dont know how loud yours is, but mine was doing the same thing, turned out to be the pcv valve.

 

[Mike T]

I would pull the belt off and run it jacked up if it needs to be in gear or give it a very quick 1 or 2 minute drive, this would eleminate the accessories. Note you will have no power steering be careful !

 

[getdowngranny]

My car does the same thing. In my case it is my heat shields on the headers. They feel tight but vibrated ever so slightly given the right rpm.

 

[TType85]

I checked the torque converter bolts they are tight. I will check the pcv valve. The sound is pretty loud and resonates when going though a underpass or enclosed area. It's either something that happens at a certain frequency (vibration from the motor/accessories at 2K rpm) or maybe that is something weird with the vacuum at that point causing something to make noise.

 

[hiboom]

passenger header rubbing on the upper a frame or down pipe touching frame?

 

[TType85]

passenger header rubbing on the upper a frame or down pipe touching frame?

Nope, all clear there.

 

[Dave Dunbar]

Torque converter shield? Turbo heat shield?

 

[Lil Truck]

Did you ever find the source of the rattling noise?

 

[Jay J]

My car does the same thing. In my case it is my heat shields on the headers. They feel tight but vibrated ever so slightly given the right rpm.

Also, if you have the stock gutted converter, check the screen/shield on the bottom--they can come loose...

 

[TType85]

Still have that noise. Different set of headers, converter, different gutted cat, new motor, and ps pump

 

[Phoneguy]

is it coming from the center of the car near the hood? Maybe the hood rattling on the stop...lube it up and see if it goes away.

Bryan

 

[Lil Truck]

Another member solved his noise problem by changing out the PCV valve.

 

[TType85]

is it coming from the center of the car near the hood? Maybe the hood rattling on the stop...lube it up and see if it goes away.

Bryan

Had that one and fixed it. That was a much louder sound


Posted from the TurboBuick.Com mobile app

 

[TType85]

Another member solved his noise problem by changing out the PCV valve.

I'll have to try that, I don't think that was changed because it was still good.


Posted from the TurboBuick.Com mobile app

 

[buickGN3:16]

check the bolts in the cross pipe that tie the headers together!


Posted from the TurboBuick.Com mobile app

 

[turbo nasty]

Cracked flexplate possibly

 

[kkash48]

Did you ever find the cause? I have the same thing happening .. In gear, moving, at 2000-2150 rpm .. less or more, it goes away .. but in that area, strange rattle. Seems to happen once the car is fully warmed up or driven awhile. Car is locked up for winter but will get back tracing it down in the Spring.

 

[NorEaster]

Ended up being the pcv. I have it stacked with a RJC pcv.