Hey guys, I went with my brother to tune his car last week. Here's what happened, he's running single cam (bonestock) turbo wit 440 injectors, 225fuel pump, and its on crome. So everything went good he got to about 217ish hp. The run after that hits 219 then we heard something rattling. Sounds like something is lose inside the motor or on the tranny side.

Checked compression test... it was good. The tuner looked through the sparkplug holes to see if anything was loose. He didnt see anything...

However, the clutch was recently installed. They said the flywheel could be loose. So we started the car to test, you can hear it clunk when the motor is on, but when you rev it would actually go away for a bit and when you let go of the gas pedal it comes right back. ANyone experienced something like this before? I did a little search on you tube it sounds like a rod knock... , but I really dont know. Maybe some of you might have an idea ^^ please help him out if you can.

 

if it goes away when you rev it, that is usually a sign of rod bearings, the knock will happen more the more you run it.


could be in an early stage still.

 

what ? no< rod knock will get louder and the pattern will get faster the higher the revs go. loose flex plate and flywheel bolts noise will go away when revved. wristpin noise will also go away if you kill spark to that one cylinder

 

cheap lightweight flywheel? my buddy had the same problem on some pos ebay flywheel,sounded like the windage tray or something downthere was loose, the cheap bolts on the two peice flywheel broke

 

you ever hear the early signs of a spun rod bearing?

a knock on the downrev and at low rpms is where it starts, few more miles and it will be knocking all the time.

 

he's on stage 3 clutch, with new OEM Fly wheels. So I dont know if that could be the reason why... I'm hoping its the flywheel

 

check your cam gear bolt, happen to me too a day after i got my car tuned started to hear a knocking sound was afraid it was a rod problem or maybe valves loose, popped open valve cover to see whats going on saw that the cam gear bolt was touching the timing cover tightin it up with some loc tite, problem went away!

 

it was pretty loud, also sounded like it was comin from the tranny... but I'll check that out thanx

 

1 question guys, if he did spun the bearing would the car be able to start?

 

yes it will most likely run. check to see if the clutch/flywheel is ok

 

does the noise go away when step on the clutch? could be throuwout/release bearing.

Also do u have a flex pipe? check the exhaust system too, it could be rattling.

 

Did you torque the flywheel/clutch on properly? Or did you just hammer it on with an impact?

I think a clear video would help.

 

a bad input shaft bearing on the trans will cause some noises that cant be described in words, lol.But seriously check the trans.

 

Your clutch or flywheel has had the bolts back out. Next time use Loctite. And take it apart NOW before you wreck something trying to figure out where the noise is coming from. Revving it more isn't going to help. I've seen this happen before, it makes a HORRIBLE rattling noise from the trans area.

 

DUmp the oil and check it for shavings. That will rule out bearings

 

Ah yes, I remember that day, lol...

To the OP, I had this happen to me (flywheel bolts backing out) and yes, it sounds just like rod knock, then when I would step on the clutch petal, it would go away.

I towed my car home, pulled the trans, and saw the carnage. All 6 bolts were backed out from 1/8 - 3/16 of an inch. The vibration was so bad, the flywheel bonded to the crank, the bolt holes were all ovaled, and on top of that the crank pulley key sheared in half an mangled the key way on the pulley! This all happened while Raene and I were doing 3rd gear pull (tuning as well). So yeah, dont keep starting it like that! lol

Anyhow, that was my experience. This time around, I cleaned the threads meticulously, red loctited them, and tourqed them in four stages.

I hope yours isnt as bad as mine (if thats what it is)

 

Happend to me as well..exactly what happend..loud noise from the tranny side pulled the trans and the bolts were finger loose.

 

does it sound like this?:

http://s234.photobucket.com/albums/e...00_0001_00.flv