I posted this in the exhaust question and got no responses. I am hoping someone can tell me why my exhaust keeps blowing through my donut gaskets. The y- pipe keeps coming loose and i keep tightening it, and exhaust blows a hole in the donut gaskets. I've replaced them a couple of times. Could this be caused by a bad cat?
i am also wondering if a custom y-pipe would be worth it. i have a 2.8 v6 camaro. i was quoted $325 for a custom y-pipe and 2 1/2" pipes going all the way back if I bring my own cat. $450 if I use their cat. does this sound right? thanks.

Chris

 

I would guess the constant blow out of the gaskets is because of a clogged cat, or a cat getting clogged. Either way its not flowing through like it should.

325 for a custom Y? Your joking right? I would not pay more then 100 for it. And thats including the material AND labor. Hell I can BUY a die for my bender for 200 and make one for 50 bucks...

The cat.. go catco high flow, call summit, 59-65 bucks.

And go to another exhaust shop like mineke or something. Forget the rip off 325 Y pipe people.

 

Thanks for the help. i thought that i had a clogged cat, but i was told when i had my muffler put on that it was hollow. the $325 was for bigger pipes going all the way back to the muffler. but it still seems kinda high. i have to get this fixed so that i can pass emmissions this month. right now i dont stand a chance.

 

I think the 325 for the y-pipe is fair. I was quoted 450-500 for a y-pipe and installation for my headers, I supply the cat. What is the point of having a y-pipe though if you dont have headers? You would see little if not any power gains if you do that.

 

Here is a Y-pipe for ya on E-bay

http://cgi.ebay.com/ebaymotors/ws/eB...tem=1811683958


bidding starts at $20, go for it!

 

Put it this way. A local shop does nothing but exhaust. I went to the guy saying I wanted a Y pipe Mandrel bent to replace the stock unit and wanted pipes made to move the tips to the center of the muffler. He wanted 125 for everything. THATS a good price. 3 tubes with 2 or 3 bends. AND BTW you can get a 2.5 inch cat back for 140ISH. Summit, Dynomax cat back. Add the 60 for the High flow cat. 200. another 100 on the y pipe and your set for about 300.

 

There isn't many places around here that will do this for my car so I have to take what I can get. 500 is alot, but if that is what it will take to get it done I'll have to do it. I dont think that y-pipe listed above on ebay will fit the long tube headers like the super Competition I have. That y-pipe is probably for the 5.0-5.7.

 

I have some recent experience with these donuts.

#1 The ones listed in the parts-guy's book are the usually the wrong ones. Make sure yours has the metal lip that fits into the manifold. Or they tell you don't need them with a straight face.

#2 Tighten each side slowly, equally, going back and forth.

Does it look like the donuts is slightly folded? or the lip bent, then you probably did what I did, and tightened one side too much before tightening the other.

I highly doubt you need a new Y-pipe, I just can't see how. If there was enough pressure to blow-out a donut, I would say you have some internal engine damage as well.

Do you think there's an obstruction?, like did you bottom it out enough to crush it?, if so get some struts and an new oil pan.

I'm positive #2 is your problem, because you say it keeps coming loose. That what happend to me.

But if you want to spend $400 (ie Daddy's paying) so in the process they put your $6 donut in right, well, Righty-ho then.


later

 

When you say "blow out a donut"- what do you mean?

The exhaust donuts on my car seem to be cast iron pieces, and probably impossible to destroy. Or, do you mean they "fall out"?

Or did GM change these things in later models to be some kind of cardboard?

 

The donuts have a soft metal gasket surface that accually compresses and a steel lip tha fits inside the manifold. They can only be reused around three times if lucky.

I rembere going through the exhaust catalogs and one said; 2.8l v6, 82-92, no flange gasket. The other said 82-84, no gasket, 85-92 listed gasket that I ordered and was wrong. I went to another parts store and they looked it up, found the same thing and just went and matched mine up.

my reciept shows the part # as MMX 521859 $8.83

later




How do you know you had too much oral sex the night before?

Your face looks like a glazed donut!

yo

 

No kidding! Maybe you guys should go hit up an older 2.8 f-body and grab the ones that are all steel or iron or whatever. I actually ground down the insides of mine to get better exhaust flow.

Hey, now that I mention it, my friend's 89 Camaro (the one I did the swap on) had the same manifold-to-y-pipe donuts as I did.

The ones I have are flat on one side, this presses against the exhaust manifold outlet. The other side is more narrow, and fits inside the y-pipe inlet. It's got no gasket surface what-so-ever. It seals by the squeezing force of the manifold studs; as you tighten the y-pipe-to-manifold nuts, the whole thing forces together so the steel donut can't move. The outside of the steel donut goes inside the y-pipe.

I took a crappy pic of how the donut looked after I ground down the inside; it came out bad, but maybe I'll scan it. That way you can see the pic of what my car uses.

 

The gasket that i have is a soft metal. I remember back before i rebuilt the engine that i had the cast iron ones on there, i dont remember what happened to those. Wish i had them now...When i say blow out a donut, i mean....i had them on tight, no exhaust leaks, and then after a week or two i had an exhaust leak and when i looked under the hood, half the donut was there and half was gone. and it did this on both sides. i replaced them and it happened again. i just bought a catco high flow cat from summit yesterday, should be here tomorrow. im hoping that will fix it. any ideas on why it keeps doing this?
I dont need a y-pipe either, i was just wondering if i would notice a big difference if i got a custom one put in. since im having all this exhaust work done, i want to get everything done at once if i can. Thanks for the help guys.

Chris

 

Tom; the one you described sound like the one I ordered and thought was wrong.

Did it have the lip i'm talking about?, Can you put it in the manifold and it will stay in there by itself? The one I ordered looked like it might work, but it wasn;t what I pulled out.'

My 87 engine had a few other pecularities. It has a counter wieght on the flexplate like '86, the harmonic balancer has three notches in it like an 86. But the engine has a serpentine belt.

 

Chris,

I would recommend trying a different brand, or if you aren't using ones like mine, try.

Interesting problem anyway.