blown out gasket between y pipe and cat
 

hey guys so today i realized a tiny change of tone in my motordyne exhaust...and not the break in tone change one that sounds like theres a leak....so i got my car up on a lift while it was at nissan for service and my buddy whos a tech told me that the gasket where the catback and the High flow cat meets is blown out. no not the headers and hfc and catback and hfc...would this Z1 Universal Exhaust Flanges (Custom Exhaust) z1 gasket fit the motordyne if i get it in 2.5 with 2 bolts? it seems shorter. my tech said that if i went with the same one due to heat its gonna blow again and that this one was good...but i dont know because im afraid it wont fit properly causing future problems

The link you posted is not a gasket but a metal flange use to fabricate custom exhausts, depending on ur CBE and HFCs pipe size, 2 Bolt Exhaust Gasket for 2.5" or 3" pipe or OEM 2 Bolt Exhaust Gasket for an oem 2.25" pipe, but i'am pretty sure most aftermarket pipes use 2.5", also to be safe I would use a nice thin coat of Gasket Makers : Permatex® Ultra Copper® Maximum Temperature RTV Silicone Gasket Maker on both sides of the gaskets.

i showed my tech he said it should work..i ordered it alrdy u think itll be fine?

Like he said you should have ordered the gasket. 2.5 in size that is too thick and you might not have a good seal. But you can try and let us know.

My gasket are blown too. I bought a gasket from Z1.

Z1 Metal HR/VHR Manifold 3 Bolt Gaskets

They have the 2 bolt gasket available. Call them before you order.

Or just follow the link posted by infiniti.

No sorry your tech was wrong, if you ordered from the link you posted, you ordered a 1/2" thick metal flange not a sealing gasket.

http://www.z1motorsports.com/240sx/i...FlangePair.jpg (flange) vs http://www.race-tech.net/images/IMG_2698.JPG (gasket)

A tube of red RTV will do the job too and you can pick it up at any auto parts store.

If OP and his mechanic can't tell the difference between a flange and a gasket, I don't think they'll be able to figure out how to use RTV. snicker

Just had my gaskets changed today here is how my CBE burnt those gasket and got replacement from Z1.


Attachment 95916

The holes don't match. It probably won't make much difference but to minimize turbulence you want the gasket to match the pipe. If the gasket is too big there will be a "valley" that will cause the gases to eddy. If the gasket is too small, you have an orifice plate.

I know Im kinda frustrated with Z1 I told them my CBE is ARK and they said this would fit perfect. Actually the holes matched its the bracket holes that are bigger.

What I did doubled up the gaskets and applied the RTV held it with Bicegrips while tightening it. Well it did seal the leak I just don't know how long it would hold. But for now the exhaust note is symphony from being like a busted trombone! Lol

This is how it looks like see how big the gap with the bolt holes.

I just had to do to make it work somehow. Till it get busted again, but hopefully it would hold. Not the best fitment but got the leak fixed.

Attachment 95917

Your original gasket inside pipe diameter looks smaller than the new gasket, did you measure them?

Yup the new gasket diameter measures just right with the pipe, the old one was my 2nd gasket that I had from the other shop and yes it was smaller that is why probably it got busted easily. The new one is only bigger at the bolt bracket.

But I think I got it under control leak is gone. Exhaust is quiet from under my seat and back to deep exhaust note from the back end.

Maybe it's just the pic (or my eyes) but it doesn't look like the pipes are lined up. You'll get the best flow when the gasket is centered and the pipes are in line.

It does looks not aligned, I'll re-check tom. :tup:

Now I wont be able sleep. Im scared my Z will blow up tom when I start it! Lol

But seriously thanks for the guidance.:tup:

yeah center the gasket for best flow just try to line everything up so it is all symetrical and ticking out the same amount all around the flange. there is no problem with slotted mounted holes in gaskets so long s you are carefull of this when assembling

:iagree: Exactly what slow said.

so what happened to OP? where you able to fix it?

blown out gasket between y pipe and cat
 

I just installed a motordyne exhaust on my G but I have a lot of leaking condensation from both of the y pipe to cat flanges. I don’t know what the deal is. I already had leaking there before the exhaust change, and I thought new gaskets would fix it. It actually only leaked at one flange before, but now it’s leaking at both. I also raised the muffler up a little bit with a jack and retightened the y pipe to get some more height as recommended on a g37 motordyne thread. It was leaking before I did that, but now it’s worse. So I think I have more then one problem. Bits of the old gaskets were stuck on there when I removed the old exhaust and I did pretty good I thought scraping the old stuff off before putting on the new gasket. But maybe I didn’t do good enough? I really don’t know how I could do any better. But I am going to lower the muffler and y pipe section down lower again to see if that helps by having more of a flat mating surface. But again I had a little leaking there before I readjusted it up higher. Is it possible to take the y pipe off and see about if I missed any bits of old gasket without taking the whole exhaust off? It is such a pain I have already made adjustments twice to raise up the middle and back end and I don’t want to lose my hard work. I will maybe try Berk gaskets and some gasket maker instead of the provided motordyne gaskets. This is so discouraging for me being my first time Installing my own exhaust having to keep raising the car back up and fix the height or leaks but I keep not getting results. any advice anyone? Maybe the bolts need to be tighter? I am tightening to 30ft lbs lol


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Permatex makes some exhaust sealants to be used along with the gaskets, had problem with my Norton motorcycle and it fixed it.

Thanks! I got some permatex and put it on there a few hours ago. Hopefully tomo when I start it up it will work lol


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interested if it works,the stuff i got was copper colored, hasnt failed or burnt away yet..

I've had the best luck with those Berk graphite crush gaskets on the Y-pipe and upper test pipe flange. No RTV or anything like that.

I will let you know tomorrow, I decided to just let it sit today and cure, just to be safe lol. If It doesn’t work I’m gonna try and scrape off the RTV and try the Berk gaskets lol I am nervous. I got the copper stuff too. If it doesn’t work maybe the y pipe isn’t lined up properly too? I noticed there is play before bolting it down. And the flanges are a little bigger top to bottom then the cat flanges. It’s also kinda hard getting the motordyne adjusted right so the v clamps don’t leak and it doesn’t sit too low. I think that also affects the way the y pipe sits lol


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Ok it is not leaking at the y pipes anymore. Haha I thought I saw some smoke coming out of the bottom for a second so hopefully it holds, I will keep an eye on it! Thanks for the help!! However, the rearmost passenger side v clamp is leaking condensation pretty bad even though I was absolutely sure I got a perfect seal on it this time. It was my 3rd time readjusting that one lol.


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