FAQ: The Exhaust Thread

deekster_caddy wrote:

Wow, another reason to vote for my cheap-a$$ knock off headers! I never had a problem like this! (although I did have to replace the el-cheapo-flex pipe and boy is it quieter!)

As did I. The guy who welded in the new flex made it a straighter exit. No more "shark tail" hanging down to the street.

I was actually thinking about the ZZP's....now I just might send the brand new cheapies I have in the garage for a good powder coat, then wrap em up.

matt270avian wrote:

To be fair, Charlie is at 160k and is still on the original stock mounts (I'm guessing anyways).

No doubt about that. I am reading some of Codiths old posts and trying to get pricing together now to do all my mounts...

Man. Fix one thing and a half dozen new things pop up. I LOVE IT!

Charlie, if it is in fact that rear trans mount, which is "hollow", a new trans mount will be fine at idle. The second you slam the throttle, the engine is going to tilt and hit the rack if the header is that close to it. I would consider getting solid or filled mounts for the front and rear. I potentially see a long-term issue if your header is touching now.

The dude in the buick thread i posted above said new mounts barely gave him the the room he needed to clear the heat shield above the rack. He said he had to crow bar the heat shield to give him the extra assurance he needed.

Can you link me to any threads you are aware of with information on solid/filled mounts? I am in this for the long run so all long term solutions are favorable at any costs.

Thanks, Scott! Ima keep reading and digging until I get this situated!

You could either cast new mounts (expensive and time consuming) or just pick up a tube of 3M WindoWeld and fill either your old mount or a new one. No matter what you pick it's worth doing, you'll notice the new feel and love it.

Just got home from work and took a look at mine. It's hard to tell without being able to get under the car, but it looks like I have about 3/4-1" of clearance between the header and the rack.

My rear trans mount is made out of three hockey pucks.

So charlie it looks like you have a rigid heat shield on your steering rack which would be another difference between the 99 and 98down equipment. Can you take that shield off?

Also I think I have a new in box rear 99 mount from the dealer. I'll check and take a picture for you

Thanks, guys. Matt, im def going to get some/fill some mounts.

Tyler, lets take some measurements and compare em and find where the difference(s) are. I am just afraid (no matter how similar we think they are) of the differences between the model years.

Cody, let me what you want for that mount, please. I will check for the heat shield Saturday and see if its something that can be modded. I am hoping that would only be a band aid fix and that the true solution will be found in the mounts. Trans/engine, whatever. The exhaust is really sounding great when I'm rolling and I think firming up the mounts is just going to make it all that much better.


In other news... my LTFT is still lean as hell after resetting trims after header install. I'ma post about this in a different thread tho

Can anyone enlighten me on what an exhaust leak sounds like? Specifically, the rear exhaust manifold. I can hear a very faint ticking noise at idle and only at idle. It gets drowned out by the sound of the engine when the hoods open and when I'm driving. I can also hear a hissing noise coming from around the back of the engine, but I don't know if that's the manifold or not. No vacuum leaks that I can find too.

I'm hoping this is the cause of my P0171 code that's been haunting me for forever.

If it doesnt increase with RPMs then it's not an exhaust leak. Ask me how I know! Can you get a video clip?

If the hissing or ticking noise doesn't increase? I can't hear either one when RPM's increase. When I do a quick rev, it doesn't snap back to normal idle RPM. It kind of takes it a second to get back to normal.

Does it sometimes go away after the car is warmed up? Mine did that.

I'm not sure. I haven't really paid attention to it after I've driven long enough for the car to fully warm up. Whenever I do hear it, It's when the car is cold. I'll try to listen to it right after school and when I get home.

Okay, started it up after school and the ticking was there. Drove home and in that time the car was able to get up to operating temperature and the ticking was still there and sounded just like it did with a cold start. I revved VERY lightly because anything above ~1300 RPM and I can't hear it. The ticking got a little more rapid as I increased RPM's.

SLP Headers FTW!

But seriously, I'm sorry to see all the problems that you're running into Charlie. That really sucks. I didn't have any of the clearance issues you're facing.

Nah man! problems = solutions = gainz!

ITS ALL GOOD!

Is there anyway to know if this is a cracked manifold or just a leaky gasket? I didn't see any black residue when I was underneath the car on any of the pipes.

Rockauto doesn't list a rear exhaust manifold for the Riviera, but they list one for the Grand Prix. Aren't they the same?

Yessir. Or just pursue your dream of having a fast Riv and buy headers! Look on craigslist, there is a guy on your side of the state selling SLPs for cheap.

They are NOT the same. The rear manifold has a different outlet angle than the GP one. Fiero guys like our manifolds for L67 swaps because ours lines up with their stock exhaust better.

matt270avian wrote:

They are NOT the same. The rear manifold has a different outlet angle than the GP one. Fiero guys like our manifolds for L67 swaps because ours lines up with their stock exhaust better.

Ahh. I was thinking ahead in case the manifold is cracked. Hopefully It's just the gasket.

Now to find someone to do it because I do not feel like doing this.

Sir Psycho Sexy wrote:

Yessir. Or just pursue your dream of having a fast Riv and buy headers! Look on craigslist, there is a guy on your side of the state selling SLPs for cheap.

I wish! Maybe if I didn't have 166K miles already.

Why not message Charlie about his? He just put on headers, so unless the rear manifold magically disappeared he should still have it.

matt270avian wrote:

Why not message Charlie about his? He just put on headers, so unless the rear manifold magically disappeared he should still have it.

Good point. I know a stock rear header won't be terribly expensive if I got one, but I'd like to avoid getting a whole new one if It's just the gasket that's bad.