Weird crackling noise

[BlackSunshine]

Hey Guys,

So, I am hearing a strange (best as I can describe it) crackling noise after I had my Hot Rods installed. Some quick background. I recently installed some BBK LT's with a catted X-Pipe and Prothane poly motor mounts. NVH is obviously greatly increased but this noise is distinctly different and somewhat intermittent.

Basically, the best I can describe it is a crackling almost like metal expansion or sort of like the sound fire embers make when they pop. It seems to happen most when cruising at around 1500-1900 RPM but will also do it somewhat when I lift off and coast with the engine idling while moving.

It does not do it while just idling when stationary and will also not do it under load or WOT. Having a buddy sitting with me in the car he seems to think it sounds like it is coming from under the drivers side floor pan or just behind the dash area on the center to drivers side area.

This has got me completely stumped and a bit worried. Has anyone experienced this after a Hot Rod install? (For clarification it was not doing it after the LT install, only a day after the cams were put it). I've gone underneath and check for clearances on the LT's and everything looks good and I tightened up the collector bolts nice and tight.

Anyone have any ideas as to what this might be? Could it possibly be the chain guides/slack adjusters rattling around or maybe a loose cam cap? How about a blown cat? (went underneath and tapped the cats with a rubber mallet with no noise) Car drives fine and pulls hard all the way up and as mentioned above does not do it under real load or at WOT.

Any help or suggestions would be appreciated.

Cheers

Any ideas or suggestions

 

[Thekid760]

I just installed my hot rods and I havent noticed anything like that.

Bump for you.

 

[BlackSunshine]

I just installed my hot rods and I havent noticed anything like that.

Bump for you.

Thing is, I don't necessarily know if it is a product of the Hot Rods or just a coincidence. I may be leaning towards a blown Cat since it started after the car was dyno tuned but they are brand new and only on the car for less than a week before the cams went in. The Prothanes really shook the car up so it could be something rattling now since it vibrates so much. Thanks for the bump. Might try and get a video of it if I can't get a handle on it.

 

[BlackSunshine]

I know it's like finding a needle in a haystack, but I will bump it once more for shits and giggles. :sigh:

 

[minivanracer]

get under the car and smack the cats with your hands with car off and cool. i busted my cats, it is possible.

 

[AbdullaGT500]

Sounds like Cat's to me honestly.

 

[BlackSunshine]

get under the car and smack the cats with your hands with car off and cool. i busted my cats, it is possible.

Sounds like Cat's to me honestly.

Thats what I was affraid of. Car is a daily driver right now and don't have the time to send the x-pipe back to BBK for warranty. They've only been on the car less than 3 weeks. Gonna pull them off this weekend if I can and inspect them.

 

[BlackSunshine]

So, I've basically come to the conclusion that the issue is the separator plate between the tranny and the motor smacking the flywheel (as per the TSB issued). It has begun to do it mostly on cold starts and distinctly sounds like the plate contacting the flywheel.

My question now is, how simple is it to drop the tranny on these cars? I should have access to a lift and tranny jack. For those who have dropped their tranny, could you chime in and let me know briefly what needs to come off in order to separate it from the motor?

Much appreciated.

 

[Rene06GT]

Not to hard, unbolt the drive shaft, and mark the location when u pull it, thus will allow u to install it the same way when reassemble (ensure no vibration) after that remove shifter and unplug any hoses or wiring to Trans, support the Trans and unbolt the bell housing and Trans support brace, when u do that remove, install ur clutch alignment tool to hold clutch and begin to unbolt the pressure plate, when unbolting go in a star pattern and no more then a full turn on each bolt until u have released all the pressure this will help prevent warping the plate, once that off u can remove the clutch and check ur fly wheel for proper clearance or warping.

 

[Rene06GT]

Oh and follow the same pattern when u reinstall the clutch and pressure plate, one turn on each bolt in a star pattern till ur done and torque to recommended spec.

 

[gil_t2]

I had the same sound, it was the cats, I have BBK LT's with there catted x pipe. The drivers side internals of the cat came loose. I put a O/R pipe on and it was gone.

 

[Rene06GT]

Think of this lets say ur fly wheel is lose, it will always have there sound. Its always spinning @ 1000 regardless. (probably 700-800) either way u should also have some vibration when u shift from the clutch making uneven contact, if this aint happening it probably aint the clutch. U may be able to lift the car up and use a pry bar to see if the assembly has some play and don't use a lot of force when checking. If this checks out good it id not the fly wheel. Use a stethoscope or even a piece of wood or hose to listen to the areas with in that u hear the noise. (one side to ur ear other to the part) this will amplify the sound.

 

[BlackSunshine]

Not to hard, unbolt the drive shaft, and mark the location when u pull it, thus will allow u to install it the same way when reassemble (ensure no vibration) after that remove shifter and unplug any hoses or wiring to Trans, support the Trans and unbolt the bell housing and Trans support brace, when u do that remove, install ur clutch alignment tool to hold clutch and begin to unbolt the pressure plate, when unbolting go in a star pattern and no more then a full turn on each bolt until u have released all the pressure this will help prevent warping the plate, once that off u can remove the clutch and check ur fly wheel for proper clearance or warping.

Thanks, but won't need to go into the clutch. That is not the rattle, will explain below.

I had the same sound, it was the cats, I have BBK LT's with there catted x pipe. The drivers side internals of the cat came loose. I put a O/R pipe on and it was gone.

Checked the cats, smacked the whole pipe with a rubber mallet and removed the rear O2 to check for debris, all solid and clean. It is still possible but the noise has changed now and I am certain its the scatter shield smacking the flywheel.

Think of this lets say ur fly wheel is lose, it will always have there sound. Its always spinning @ 1000 regardless. (probably 700-800) either way u should also have some vibration when u shift from the clutch making uneven contact, if this aint happening it probably aint the clutch. U may be able to lift the car up and use a pry bar to see if the assembly has some play and don't use a lot of force when checking. If this checks out good it id not the fly wheel. Use a stethoscope or even a piece of wood or hose to listen to the areas with in that u hear the noise. (one side to ur ear other to the part) this will amplify the sound.

I don't believe it has anything to do with the clutch or flywheel (persay). Please look at the TSB link below:

http://www.stangnet.com/images/stories/docs/s197_TSBs/08-02-10.pdf?37e6df

This is what I am positive it is now that I have listened to it. It does it quite violently when just started and driven for the first 5 mins or so. It almost sounds like something is broken and then mysteriously goes away and may happen intermitently at certain RPM vibrations. Just need to pull the tranny and replace the plate. Fingers crossed.

Thanks for the replys, appreciate it.

 

[BruceH]

The seperator plate can be removed without pulling the transmission. It will have to be pulled back a few inches but that's it. Just enough to clear the alignment dowels.

 

[BlackSunshine]

The seperator plate can be removed without pulling the transmission. It will have to be pulled back a few inches but that's it. Just enough to clear the alignment dowels.

Cool beans. Thanks Bruce. Question, is there REALLY any need for that damn peice of sheet metal? Know anyone who has ripped it out and left it off?

 

[BruceH]

Cool beans. Thanks Bruce. Question, is there REALLY any need for that damn peice of sheet metal? Know anyone who has ripped it out and left it off?

I've often wondered that myself. There has to be a reason. A guess would be it has something to do with expansion or nvh.

 

[BlackSunshine]

I've often wondered that myself. There has to be a reason. A guess would be it has something to do with expansion or nvh.

I guess really no reason to leave it off. It's only like $20 bucks. Ahh well, a job for one weekend.