Exhaust manifold/heat shield issue (turbo also)

[staticbrainwash]

Alright kiddies. Lately i've noticed that when i rev up a bit in my car i get a nasty rattle from the exhaust manifold area. At first i thought it may be a crack making lots of noise, so i removed the JM polished heat shield i have and fired her up and did a couple quick revs. Sound is gone.

Hmmmmm, odd right? So i put the shield back on with a couple washers underneath it as spacers in case it's hitting on anything, and boom, still makes the noise.

Could this still be a small crack? Because it seems like it's rpm dependant. Hits around 2-3k then is gone before or past that. I'm begining to feel slightly crazy with this because it was a fresh 2g manny i put on, and all i see on it now is what looks like a surface chip.

This is also where i'm seeing my knock at 10psi on stock 450cc's with 2g pistons. I'm guessing they're related because there's not reason i should be getting knock on that low of boost. And yes, i have leak tested. My ONLY leak is around the turbo somewhere that i can't figure out even with soapy water. If you've got ideas on that too, let me know, i'm stumped here. This car has less than 4k on the new motor and it feels like a turd.

 

[staticbrainwash]

Would it be possible to take some heat wrap or shielding (flexible) and run under the JM shield to give the space between some padding if it is the manifold vibrating on the shield? Or is there an easy way to test to see if the manifold is cracked. I just don't think it's sracked because i imagine that would be more of a problem all the time. Arg, someone fix this car for me.

 

[Talesin]

Make sure your turbo bolts aren't sticking up too far... I've seen people with a ridiculous number of washers between the bolt and the manifold, which raises it up a whole lot. Also make sure one of the turbo bolts hasn't backed itself loose. If the JM shield has more than one bolt point, make sure all of them are on and snug.

Also, see if it still makes the rattle if the hood is open. Was having a weird problem and thought it was my upper heatshield, turned out to be both my hood rattling (fixed by unscrewing the rubber 'feet' at the corners by a quarter turn) and my downpipe rattling against the oil filter (fixed with a new filter, the one that was put on was an extra-capacity).
Rev it by pulling on the throttle cable and make sure the rattle is still there, and reliably so. Then just set something heavy on top of the heatshield and try again. If it's the shield itself, that should stop the rattle reliably. Then yes, just put a 'pad' between the shield and whatever it's hitting... not much under there to serve as contact points, after all.

 

[staticbrainwash]

It looks like it's getting hit by one of the turbo bolts, i'll check washers on it, thats a good call.

I found the rattle with the hood open revving it like that, so i know thats what the noise is. I was just hope it isn't my turbo, and was quite relieved when it went away with the shield gone.

Now i just need to figure out the weird knock at low boost, and where this damn boost leak is around my turbo. Ugh.

 

[Talesin]

You can also put a little dab of shoe polish on the top of each bolt and put the shield back on carefully. Soon as it taps, it'll leave a mark so you know which specific one's causing the problem.

 

[staticbrainwash]

Alright, tonight i pulled off the manny for a couple runs, and it looks like, my knock is down to about 7 counts as a high. So either it was the small leak i fixed at the compressor outlet elbow, OR it was the manny. We'll see what happens.

On a different note though, as i was driving around tonight, my cel flashed for a tps. Just flashed for a sec, then the car drove like ASS. Wouldn't shift out of 2nd (it's an a/t). I had to turn off the car, and then it was fine. Bad tps maybe?