HELP ME PLEASE!!! Rattling/Knocking sound!

[V8killR4U]

PLEASE HELP! Im trying to figure out what this rattling/knocking sound is

The noise only occurs under hard acceleration/WOT. The car does not knock on the scan master. It doesnt matter if its 25lbs of boost or 15lbs it does the same thing. It sounds like something knocking/rattling up against the firewall. The car drives around perfectly fine normal driving...motor cant have more than a few thousand mile on it. Turbo is good, New Billet converter and trans from Brian. Double roller timing chain, Cam sensor is good, Cometic HG. I just cant figure out what this could be. I never really noticed it before, but the noise seems to be more pronounced now. Heads are torqued down properly, valve train seems to be in good condition.

I put the car on the hoist last night. Looked under the car and nothing obvious was loose or out of place. Started the car and had two people looking and listening for any wierd noises...nothing. Put the trans break on and built boost to try to simulate the noise...nothing. I honestly dont think its internal in the motor and neither does my mechanic.

Its almost like something is shifting or moving under hard acceleration and causing this noise. (thus it didnt make this noise under boost on the trans brake on the hoist)

PLEASE ANY ADVICE...Its driving me nutz!!!!!!!!!

 

[V8killR4U]

Really need your help guys...

 

[V8killR4U]

What do you think about this...

The Starter gear in the starter isnt retracting all the way and hittnig the fly wheel.

Would a bad exhaust leak or cracker header sound like this ?

 

[chrisgarrett]

Could be the converter.

 

[V8killR4U]

Could be the converter.

Converter bolts are tight and the converter is new...

 

[chrisgarrett]

Even a new converter can make noise. It's probably not your converter but that's my first guess based on what you described. :smile:

 

[49-blues]

How about bad engine mounts & downpipe hitting firewall?

 

[ttypewhite]

Got your pm, The wife and kids are good.
Lets try and check these things:

1) double check that the motor mounts are on the correct side facing the right way. I have done this in the past and it cracked the tranny housing around the converter

2) double check your harmonic and make sure it is tight (impact gun)

3) when you installed the converter, did it give 3 clicks as it went into the tranny? How much of the neck of your converter is exposed when you look underneath? is it shimmed by the flywheel?

4) Do you have a SFI flywheel? might be cracked if its stock.......just throughing that out there.

5) Might be the converter, do you have another one to swap and check it out?

6) Dipstick tube secured properly and not loose

7) do a oil change and see if any material is in the pan (trust bearing), how is your oil pressure?

 

[turboc87gn]

SounDs like your flywheel may be cracked and about to break..I had a car do that but it wasnt a TR it made noise and i couldnt figure it out and one day while i was driving the center tore out of it ..It didnt cause much mayhem and destruction it just left me stranded on my way home from work...

 

[V8killR4U]

Got your pm, The wife and kids are good.
Lets try and check these things:

1) double check that the motor mounts are on the correct side facing the right way. I have done this in the past and it cracked the tranny housing around the converter

2) double check your harmonic and make sure it is tight (impact gun)

3) when you installed the converter, did it give 3 clicks as it went into the tranny? How much of the neck of your converter is exposed when you look underneath? is it shimmed by the flywheel?

4) Do you have a SFI flywheel? might be cracked if its stock.......just throughing that out there.

5) Might be the converter, do you have another one to swap and check it out?

6) Dipstick tube secured properly and not loose

7) do a oil change and see if any material is in the pan (trust bearing), how is your oil pressure?

Mike, thanks for the reply.

1)Motor mounts are good and on correctly

2)Didnt check the hamonic Balancer

3)I did get the 3 clicks when the converter went on. Not sure how much the neck is showing i"ll have to check later. Im not sure what you mean by being shimmed by the flywheel?

4)Stock flywheel

5)Im sure I could get a hold of one. Its a new billet converter from Brian on here

6)Dipstick tube is tight.

7)Oil Pressure is good, I didnt drop the pan.

 

[TurboRegal84]

Have you verified that the Knock Sensor on the car is functional? Scanmaster will only tell you what that sensor is reading. If it was not torqued properly or not functional you will not get a reading at all.

To test it take a small hammer or wrench and tap on the block near the sensor. While looking at your scantool.

 

[4-71/Z-28]

Have you verified that the Knock Sensor on the car is functional? Scanmaster will only tell you what that sensor is reading. If it was not torqued properly or not functional you will not get a reading at all.

To test it take a small hammer or wrench and tap on the block near the sensor. While looking at your scantool.

hey, thats what i was gonna say:smile: the rattling sound you describe sounds like detonation, although im not sure what would say uncle first, the cometic or the piston, probably the piston. have you checked the plugs?

 

[V8killR4U]

I've recently checked the plugs and they look good, the knock sensor does work. Also Boost is at 15lbs currently with dual alchy nozzles. I dont think it would be knocking at that level with alchy on top of that...

 

[ttypewhite]

Mike, thanks for the reply.

1)Motor mounts are good and on correctly

2)Didnt check the hamonic Balancer

3)I did get the 3 clicks when the converter went on. Not sure how much the neck is showing i"ll have to check later. Im not sure what you mean by being shimmed by the flywheel?

4)Stock flywheel

5)Im sure I could get a hold of one. Its a new billet converter from Brian on here

6)Dipstick tube is tight.

7)Oil Pressure is good, I didnt drop the pan.

Sometimes when the converter does not go far enough into the tranny you have to add some shims or washers between the flywheel and converter to give you the proper depth needed.

Try and get the car back on the hoist and rotate the motor and look really well at your flywheel for cracks. If its not the flywheel then you have illimunated the motor as a source, and I know it sucks, but it sounds like your gonna have to re and re the tranny and possibily swap out converters to illimunate that as a source as well. Avoid driving this as much as possible until you track this down. Noises are in most cases a sign of something is not right. The last thing you want is something snapping/breaking or leaving you stranded somewhere.

 

[Phoneguy]

I had a very loud sound under the hood of my car at 15lbs that sounded like marbles going through a fan. I had Cometics on the car and they were always weeping a little water even with the GM tabs. The noise turned out to be the heads lifting. Cometics on an un-machined surface doesn't seem to work very well. HTH

Bryan

 

[V8killR4U]

I had a very loud sound under the hood of my car at 15lbs that sounded like marbles going through a fan. I had Cometics on the car and they were always weeping a little water even with the GM tabs. The noise turned out to be the heads lifting. Cometics on an un-machined surface doesn't seem to work very well. HTH

Bryan

No water leaking here and check the torque on the bolts up to 75 ft lbs and it checks out ok....

 

[ELLISDALLASWE4]

rattle

check the PUCK and make sure it is not rattling... put a temp small spring on it or readjust it for short trip ... see if the sound is different

 

[TurboV]

T.V cable? check for loose or flapping cables or lines. Which side do you hear it most coming from?

 

[TurboV]

By the way..... That ttype white is Bad A$$!...

 

[xclrate]

Timing chain has play and hitting timing cover?
Flywheel cracked?
Starter bendix not retracting after starting?