I HATE EXHAUST LEAKS! (3800SC)

Golden86 · Post by **Golden86** » Tue Jul 11, 2006 12:14 am

I have replaced my exhaust manifold gaskets twice with the Flepro gaskets, and it still leaks like hell. I am not just talking about one or two leaks, but atleast 4 or so, somewhere. Does anybody know of a better way of sealing the manifold gaskets, can I use that copper spray, or is that just for head gaskets?

Also my entier exhaust system is only being held up by two mounts at each tip, and at the flange istelf. I think this has to be putting stress on the manifold. Is there a better way to support the exhaust, like is there any special hanger or something that I can bolt to the trunk wall to support the exhaust.

This wouldn't be such a big deal on the 2.8, but on the 3800's, the knock sensor picks it up and retards the hell out of the engine. And also it sounds like crap.

Shaun41178(2) · Post by **Shaun41178(2)** » Tue Jul 11, 2006 12:17 am

I have used copper spray on the exh works good

Sinister Fiero · Post by **Sinister Fiero** » Tue Jul 11, 2006 1:08 am

Golden86 wrote:I have replaced my exhaust manifold gaskets twice with the Flepro gaskets, and it still leaks like hell. I am not just talking about one or two leaks, but atleast 4 or so, somewhere. Does anybody know of a better way of sealing the manifold gaskets, can I use that copper spray, or is that just for head gaskets?

Also my entier exhaust system is only being held up by two mounts at each tip, and at the flange istelf. I think this has to be putting stress on the manifold. Is there a better way to support the exhaust, like is there any special hanger or something that I can bolt to the trunk wall to support the exhaust.

This wouldn't be such a big deal on the 2.8, but on the 3800's, the knock sensor picks it up and retards the hell out of the engine. And also it sounds like crap.

Golden, I have never had a problem with exhaust leaks on the 3800's using the factory stainless shim gaskets. What gaskets are you using and where are the leaks exactly? Pics?

-ryan

Series8217 · Post by **Series8217** » Tue Jul 11, 2006 1:27 am

Golden86 wrote: Also my entier exhaust system is only being held up by two mounts at each tip, and at the flange istelf. I think this has to be putting stress on the manifold. Is there a better way to support the exhaust, like is there any special hanger or something that I can bolt to the trunk wall to support the exhaust.

You running it with the stock crossover so the downpipe comes out the back?
Is the flange solid or do you have a flex joint or seal somewhere?

Golden86 · Post by **Golden86** » Tue Jul 11, 2006 9:54 am

I am using the felpro gaskets, I havnt tried the stock seal ones yet.

I sounds like the leaks are comming out the top of the manifolds, I just used a rubber tube to listen to them.

Yes I am sing the stock crossover, and and there is no flex joint on the system. I believe this is my problem, but I do have poly engine and trans mounts, and a poly dogbone, so the engine doesn't move that much.

Like I was saying in the other post, is there some sort of hanger that I can wrap around the mounting flange to support it ther? I am not about to chop up the exhaust when I just finished it.

Here is a pic of the exhaust from the bottom, it might help you get an idea of what im working with. BTW it is a 3" exhaust

Kohburn · Post by **Kohburn** » Tue Jul 11, 2006 10:20 am

you should have no problem splicing a flex joint into that straight section up top.

otherwise no matter what you do you will get leaks if not cracked and broken exhaust

Sinister Fiero · Post by **Sinister Fiero** » Tue Jul 11, 2006 10:55 am

I too would recommend running a flex joint. Even with poly mounts, vibration and a little bit of movement still occur which can put stress on the manifolds.

I have never used the Felpro exh manifold gaskets; I have only ever used the stainless steel GM shims.

-ryan

Series8217 · Post by **Series8217** » Tue Jul 11, 2006 10:23 pm

Yeah definitely put a flex joint in there or convert that flange to a flexible ball type with a flare and cone gasket.

The Dark Side of Will · Tue Jul 11, 2006 10:28 pm

Needs a flex joint.

Take your decklid off and go for a drive... might need to install a helper in the driver's seat for this one.

Have the helper remove her blouse and bra. Then have her floor the gas and generally romp on the car. Watch how far the engine moves as she's going from zero throttle to wide open and back. Watch the engine while she holds a low gear and goes from high RPM WOT to full engine braking and back again. It'll probably move a lot more than you think.

Then consider that while the engine is moving that far, the exhaust tips are constrained fairly well... you then won't be surprised that your exhaust is leaking.

Series8217 · Post by **Series8217** » Tue Jul 11, 2006 11:36 pm

The Dark Side of Will wrote: Have the helper remove her blouse and bra.
[...]
Watch the engine
[...]

:scratch:

Jinxmutt · Post by **Jinxmutt** » Wed Jul 12, 2006 12:20 am

I believe the flange i'm using for my exhaust came from Golden86, and I have the flange as well as two hangers supporting my exhaust. One hanger on each side, prior to the 90Âº bend to exit the rear. I DO however have a flex and I have no exhaust leaks.

I'm using the cheapo fel-pro fiero material exhaust gaskets until my new manifolds come in. I will then use the GM style steel.

I agree with the others that the flex could be your issue.

Golden86 · Post by **Golden86** » Wed Jul 12, 2006 12:28 am

ok, I guess anyhting I do to the exhaust gaskets, it will just be a temp fix unless I put a flex joint in there.

Does anybody know of a good 3" flex jount that is less than 6" long?

I will have to try the metal gaskets from GM, my dads 3800 doesn't leak at all, but thats in an impala.

Thanks

Sinister Fiero · Post by **Sinister Fiero** » Wed Jul 12, 2006 12:59 am

Golden86 wrote:ok, I guess anyhting I do to the exhaust gaskets, it will just be a temp fix unless I put a flex joint in there.

Does anybody know of a good 3" flex jount that is less than 6" long?

I will have to try the metal gaskets from GM, my dads 3800 doesn't leak at all, but thats in an impala.

Thanks

I get my 3" flex joints thru my local NAPA. They are a real PITA to order if your Napa parts person doesn't know about them.

The part number I have purchased them under is FT30008N. They are made by Marwill. You might have to have your NAPA parts person order them thru "Jobber Service".

Measurements: overall the piece measures 8". The flex joint itself only measures 4" and there are two 3" dia x 2" long pieces of pipe welded to the flex center section.

These retail for about $52.99 around here.

Golden86 · Post by **Golden86** » Wed Jul 12, 2006 1:17 am

Sinister Fiero wrote:
I get my 3" flex joints thru my local NAPA. They are a real PITA to order if your Napa parts person doesn't know about them.

I will be in for a fight then, because my NAPA knows CRAP about anything they sell.

Hopefully the part number will show them right to what I need, I don't want to deal with them long.

Thanks again Ryan

The Dark Side of Will · Wed Jul 12, 2006 8:16 am

I've found CarQuests to be pretty universally good with their catalogs and knowledge of what they carry.

Both CQ and Napa, however, are way above Advance and Autozone.

The Dark Side of Will · Wed Jul 12, 2006 8:19 am

Series8217 wrote:
The Dark Side of Will wrote: Have the helper remove her blouse and bra.
[...]
Watch the engine
[...]
:scratch:

Yes, the primary purpose of the exercise is to see how far the engine moves under load. Other things are secondary. However, if she gets into the gas hard enough to cause wheel hop, that could be an excuse to take your eyes off the engine.

Golden86 · Post by **Golden86** » Wed Jul 12, 2006 11:58 am

Yes, the primary purpose of the exercise is to see how far the engine moves under load. Other things are secondary. However, if she gets into the gas hard enough to cause wheel hop, that could be an excuse to take your eyes off the engine.

well that sucks, my girlfriend can't drive a 5 speed...

Mach10 · Post by **Mach10** » Wed Jul 12, 2006 12:30 pm

jackrabbit starts with no top or bra?

You gonna tell me that isn't worth the price of a clutch?!? :love10:

Real Fiero Tech

I HATE EXHAUST LEAKS! (3800SC)

I HATE EXHAUST LEAKS! (3800SC)

Re: I HATE EXHAUST LEAKS! (3800SC)

Re: I HATE EXHAUST LEAKS! (3800SC)