[Nenehubert]

I just got back from a lovely week in NYC and fired up the car to this lovely sound. Is this an exhaust leak? I took some crude footage with my iPhone. Any feedback would be much appreciated. I'm going to try and get the car up in the air this weekend to poke around, I don't feel any power loss if that helps.



So, apparently I cannot upload mp3's <img src="/forum/images/smilies/968/glare.gif" class="smilie" alt="" />



Thanks,

Rene



Here's a crappy youtube clip I made from the audio. [media]http://www.youtube.com/watch?v=7sb0KmhRb9I&feature=youtu.be[/media]



Ps, I meant go-kart.. too many margaritas at happy hour, <img src="/forum/images/smilies/968/beer.gif" class="smilie" alt="" />

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[craigawoodman]

Not sure a week would do it, but longer would definately cause lifter noise as the 968 has hydraulic lifters. I had my car getting panel beated after a small excursion into the tyre bundles and when I picked it up, it sounded like it had dropped a valve (but this was around a month). I immediately took it to my mechanic (driving it very gingerly) and it got slightly better. He immediately told me what was wrong and to go and give it a really good drive.



It still could be an exhaust leak, but unless it was just ready to happen - it is unlikely that this would happen with the car parked.



Once again, if in a garage, should not occur, but an engine mis-fire could be moisture in one of the spark plug bores and the electrical pulse shorting out (mis-fire in one cylinder).



Anyone else have other suggestions?

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[tamathumper]

Sounds like a lifter to me, I had them all deflate on the 944S one time after working on the engine and it sounded like a bucket full of marbles for a few seconds when I started it up. Stupid question, but hard to tell from the video,... is it a hard "clack" or a softer "poof" sound?

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[ds968]

I heard lifters " chatter " a bunch of times, but do not recall that also translating to the exhaust note although I was inside the car so perhaps did not hear it as well. ( or, I was so focused on that engine rattle I simply ignored everything else ) The video's sound clip does however seem to have a strong exhaust rumble pattern so I was also wondering if it was a leak ; when one of my exhaust pipes connecting clamps slipped off I recall the car sounded like a tractor..a really, really loud tractor !! But that wasn't just a small leak, the pipes were probably 1/4" apart from eachoter.

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[Nenehubert]

I'm not hearing anything at speed or at idle. I took some more footage on my way into work this morning and will post it later today. I commute 50 miles a day, and the noise didn't start until I got back this week. I recently did a front seal and timing belt job, so I'll check the timing when I get home today to make sure nothing is off.



As for the noise itself, it's more of a poof and not the tick-like noise we get from our injectors. I'm only getting noise as I'm accelerating. Wouldn't lifter noise be heard at idle? But I guess same could be said for exhaust noise.

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[flash]

sounds like an exhaust leak to me

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[Chris Vais]

Doesn't sound like lifter chatter to me either. I'd check to be sure there is no moisture down in the plug bores. If everything is dry, may be exhaust leak.

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[Nenehubert]

Okay, I lifted the car up, and it seems like the noise is coming somewhere from the exhaust header towards the cat. I felt around for cracks when the engine cooled but couldn't feel anything. I have water leaking from above the oxygen sensor and it's not coolant, It's dripping rather constant while the engine is running. Is this from the A/C?



Should I try and create some back pressure by having someone hold a rag over the tailpipe to help locate it?



There's also a sizable gap between the cat and my B&B. Is this normal? The bolts are rusted and aren't moving from what I can tell... it's not coming from there.

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[tamathumper]

The water above the oxygen sensor is condensation from your AC unit, no worries.



The two sections of exhaust pipe should be sealed together by a metal ring that's positioned well inside the flanges - you may be able to see it with a flashlight directed up between the flanges, otherwise it's too dark to see up in there very well. If the ring is missing, you'll have a pretty major exhaust leak.



I got a good listen to your recording on my desktop instead of my laptop, and it sounds much more "poofy", e.g. exhaust leak rather than "clacky" lifter noise.

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[Nenehubert]

Unless I have a crack at one of the Y joints. After dinner I'll try and get in there some more and poke around. It sounds like a tractor. Perhaps it's time for new headers <img src="/forum/images/smilies/968/biggrin.png" class="smilie" alt="" />

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[flash]

B&B systems are notorious for cracking.



that is a huge gap though. it should be closed, and if it is like other systems, there should be a gasket there. get new bolts and nuts. do not try to tighten those.

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[ds968]

[quote name='flash' timestamp='1345771396' post='131516']B&B systems are notorious for cracking.

.[/quote]



Nonsense. Not one single recorded / documented case of a BB system cracking or similar defects..ever. False crap stories spread by their so-called ( wannabes ) competition. Trust me on this, I have done extensive research before I bought mine , including searches on Corvette forums, Viper forums, Ferrari forums, other Porsche forums ( in that order, the largest buyers of BB exhaust systems ..) consumer reports, shotgun Internet searches for any reported BB problems.. Nothing, not one single reference to an issue with any BB. For that matter, no problems found with Borla either, but quote a few adverse experiences with a couple of other well recognized and widely sold brands, which I won't mention here.

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[ds968]

I looked at my catback connection point - no gap whatsoever, but I also cannot tell if there is a gasket squeezed in there. Even though I installed the thing myself I do not remember if it did or did not have a gasket ( that was about eight years ago, I can hardly remember things from last week ! )

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[flash]

lol - there are plenty of them - i've seen 3 cracked ones at my house. another site listed a half dozen more before it went down (all before anybody else was even making a system). i think you're just stuck on the system, and looking at the world through rose colored glasses. yours hasn't cracked yet - that's great. i sold one that was cracked and had to be repaired before i could sell it, and sent another one out for repair for a local guy (in fact, you came down while the car was still at my place and saw it). i have to think that it is pretty common if i have seen 3, and that is only a small percentage of the cars with them.



the upside is that B&B takes care of it. the downside is that you have to send them the entire system.



i have no love for any system out there to date, don't like any of them at all, don't sell one, and could care less what anybody runs, but the B&B is known for welds failing, and there is plenty of evidence out there.

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[tamathumper]

My connection at the cat uses a thick steel ring, not a gasket. There is a gap there because the ring is more like a "ferrule" that goes on the ID vs. a copper pipe ferrule that would go on the OD.

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[flash]

yeah - i think that's what is there stock. flat flange systems usually use a flat copper gasket, but the cat is chamfered, so if they matched that, it could have one of those rings. if they didn't also chamfer the inside of heir system though, the ring could break and tear the heck out of the internals of the muffler. i can't remember what the B&B uses, i only had to remove 2 of them to get them fixed, and they were years ago.

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[Nenehubert]

Found it, I checked to see how secure the nuts were at the manifold, and sure enough one of the lower studs on the last cylinder broke right off. Hopefully there's enough stud left to remove it with a pair of vise grips. It's going to be damn near impossible to drill and tap at that location without removing the head. I ordered new gaskets for all connections to make sure, if i can remove that stud. <img src="/forum/images/smilies/968/glare.gif" class="smilie" alt="" />

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[Lord_Galva]

Dam.

I replaced all my exhaust bolts during the last rebuild to prevent breakage later.

I'd try removing the heater line that runs parallel and try out your vice grip. You may get lucky.

If it does work, spend a few bucks buying new bolts. <img src="/forum/images/smilies/968/happy.png" class="smilie" alt="" />

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