Discussion
So I did the full detail job on the S4 over the weekend and finished up last night in preperation for getting her out and about this week. Drive to work was wonderful and I just got back from lunch, another glorious drive. However, coming down the highway, I was in the left lane. I get on it some and hear a nice PFTPFTPFTPFT exhaust-leak-like sound. onderful. It doesn't do it at idle or just cruising, at least that I can hear, but once you get into boost, you
hear it. Could it be that a bolt or something is loose and under boost it leaks but is fine otherwise, or at least not audible? The manifold is the new design, jethot coated and installed by the PO maybe 2 years ago. Could it be cracked already? If so, what is the common areas it cracks, to help me in my search? I just hope it isn't cracked and that it is something stupid like a loose exhaust bolt or something.
Could it also being the turbo letting go?
Rich
1994 S4
hear it. Could it be that a bolt or something is loose and under boost it leaks but is fine otherwise, or at least not audible? The manifold is the new design, jethot coated and installed by the PO maybe 2 years ago. Could it be cracked already? If so, what is the common areas it cracks, to help me in my search? I just hope it isn't cracked and that it is something stupid like a loose exhaust bolt or something.
Could it also being the turbo letting go?
Rich
1994 S4
Get under there and take a look. I think a common place to crack is between 2 and 3, just at the front of 3. Mine was cracked there, and in a couple other places as well, but it was not the latest version of the manifold. It was the 3333 version that was used on the SE's. I repaired it by welding it up and it is doing fine.
Does it sound like exhaust or boost? Pulsatile or constant? Are you making boost OK? Could also be a gasket. There are only 5 of them between the head and the turbo and 3 more joints after. Make sure all the studs are in the head and nuts are on them all. Should have the lock plates under the nuts too. They put those lockplates there for a reason.
Dr.Hess
Does it sound like exhaust or boost? Pulsatile or constant? Are you making boost OK? Could also be a gasket. There are only 5 of them between the head and the turbo and 3 more joints after. Make sure all the studs are in the head and nuts are on them all. Should have the lock plates under the nuts too. They put those lockplates there for a reason.
Dr.Hess
Makes boost fine. I actually hear it only when boosting. Kind of sounds like when you put a playing card in the spoke of your bicycle. I am going to take a look tonight, wanted a specific lead on where to look at common crack points int he manifold. Thank you for pointing that out.
I just hope it is something stupid like a gasket or something. Even the turbo would be OK as I have a spare I am sending out shortly to get upgraded. I just don't want it to be the expensive manifold, especially since it is newer, of new design and jethot coated.
I just hope it is something stupid like a gasket or something. Even the turbo would be OK as I have a spare I am sending out shortly to get upgraded. I just don't want it to be the expensive manifold, especially since it is newer, of new design and jethot coated.
So I crawled underneath real quick tonight to see what I can see. I spoke with Jeff from JAE and he mentioned he has never heard of the newer manifolds cracking and mentioned a "B" prefix. Well since mine is jethot coated it is hard to make out but it looks like the number is C910E 2333. It does have the 2 long ribs on the underside which he mentioned was on the newer manifolds so I am assuming I have the newer design. Can anyone verify? Either way, i didn't see or feel any cracks, although parts of the sucker are hard to reach. I checked all the nuts and they all appear to be there. I say appear because the back one is impossible to see but I think with a mirror I saw it and think I was able to touch it to verify its existence. All that I could get to were tight. I was able to tighten the turbo to cat pipe bolts a little but I don't think that would do it, right? All other exhaust connections looked good and all other nuts and bolts were tight.
I am now thinking perhaps turbo? It does have 60K on her. When I pulled into the garage tonight, I revved it up and held higher RPMs and no noise. On the drive home, everytime I went into boost, I heard it. Sounds like cards in the spoke of a wheel... almost like the turbo when you get off boost, the flutter it does, but a little louder. I don't know as the only turbos I blew up never made a noise, they just spewed oil.
Any other ideas?
Thanks, Rich
I am now thinking perhaps turbo? It does have 60K on her. When I pulled into the garage tonight, I revved it up and held higher RPMs and no noise. On the drive home, everytime I went into boost, I heard it. Sounds like cards in the spoke of a wheel... almost like the turbo when you get off boost, the flutter it does, but a little louder. I don't know as the only turbos I blew up never made a noise, they just spewed oil.
Any other ideas?
Thanks, Rich
The part number of the SE manifold (not the new one) is A910E2333. The S4 part number is A910E2588K. Tim had a posting somewhere with the latest part number, which I have archvied somewhere I can't find right now. Might be the 2588. The turbo should have had lock plates on it too, so you should not have been able to put a wrench on any of the nuts with the lock plates there. If the lock plates were not there, that means someone did a half arsed job at it.
Dunno about your noise. The turbo should be spinning at around 50K or X*10^4 anyway, and I don't think that would be a bicycle spoke noise. I know what that bicycle spoke noise is, as I had many of them 35 years ago. Even had an official Matel thing that mounted on my handlebars to make noise. Course, now I have a Harley that makes all the real noises... Guess I never grew up.
Does the noise vary with RPM? With the frequency, that would seem to indicate an exhaust leak of perhaps one cylinder. At 4K RPM, that should be around 2KHz. Any black soot spots? Lines at all on the manifold?
The largest crack on my 333 manifold was behind #4 where the whole thing comes together, but it was also cracked at the front of #3, which was very hard to see on the car. I actually didn't find it until I pulled it and inspected it closely. Kind of one of those Oh Crap moments when you find out that your simple weld job has turned into three times the work you thought it would be (not counting getting the damned thing off, doing the cad work on the lock plates, finding a shop to water jet them...)
Dr.Hess
Dunno about your noise. The turbo should be spinning at around 50K or X*10^4 anyway, and I don't think that would be a bicycle spoke noise. I know what that bicycle spoke noise is, as I had many of them 35 years ago. Even had an official Matel thing that mounted on my handlebars to make noise. Course, now I have a Harley that makes all the real noises... Guess I never grew up.
Does the noise vary with RPM? With the frequency, that would seem to indicate an exhaust leak of perhaps one cylinder. At 4K RPM, that should be around 2KHz. Any black soot spots? Lines at all on the manifold?
The largest crack on my 333 manifold was behind #4 where the whole thing comes together, but it was also cracked at the front of #3, which was very hard to see on the car. I actually didn't find it until I pulled it and inspected it closely. Kind of one of those Oh Crap moments when you find out that your simple weld job has turned into three times the work you thought it would be (not counting getting the damned thing off, doing the cad work on the lock plates, finding a shop to water jet them...)
Dr.Hess
No lock plates on the turbo to cat pipe connection. Lock plates on everything else.
I could be wrong about the noise but that is the first thing that came into my mind when I heard it. Hard to describe a noise, ya know? Toi me it sounds like an exhaust leak but I can't for the life of me think why it would only happen on boost.
As for black soot spots, not really but hard to tell. Car is dirty underneath.
Noise does ot vary. Off boost or free revving, nothing. ON boost you hear it and from what I can rememeber, you just heard it. Didn't vary, didn't get louder. I will reconfirm this tomorrow though when I drive into work.
I will probably go back out tonight, to double check visually for cracks, just to be as sure as I can without pulling it.
Thanks for your help.
I could be wrong about the noise but that is the first thing that came into my mind when I heard it. Hard to describe a noise, ya know? Toi me it sounds like an exhaust leak but I can't for the life of me think why it would only happen on boost.
As for black soot spots, not really but hard to tell. Car is dirty underneath.
Noise does ot vary. Off boost or free revving, nothing. ON boost you hear it and from what I can rememeber, you just heard it. Didn't vary, didn't get louder. I will reconfirm this tomorrow though when I drive into work.
I will probably go back out tonight, to double check visually for cracks, just to be as sure as I can without pulling it.
Thanks for your help.
Double checked everything. I don't see any cracks in the spaces that can be seen with the manifold on the car. I did notice some carbon buildup around #4 (closest to the rear). I was able to turn the top nut almost a full turn and the bottom 2 maybe 1/2 - 1 turn. No carbon build up I can see on any other cylinder. I guess we will see... hear tomorrow.
Either way, how in the world is a human with normal tools supposed to tighten those nuts? And what are those retainers made out of? They are impossible to push back. Space is an issue too.
Either way, how in the world is a human with normal tools supposed to tighten those nuts? And what are those retainers made out of? They are impossible to push back. Space is an issue too.
A misadjusted BOV sort of sounds like that when it opens up under boost.
Other than that I'm sure you checked the obivious stuff like the 3 bolts that hold the turbo and the cat together and the pesky EPBV. Sometimes when the EPBV is not centered it will leak at the mating surface or the flapper will rub and stick. It makes a sound similar to what you describe. USA it is more apparent when you travel in the left lane of the hwy that has a concrete barrier and the sound bounces of it.
Other than that I'm sure you checked the obivious stuff like the 3 bolts that hold the turbo and the cat together and the pesky EPBV. Sometimes when the EPBV is not centered it will leak at the mating surface or the flapper will rub and stick. It makes a sound similar to what you describe. USA it is more apparent when you travel in the left lane of the hwy that has a concrete barrier and the sound bounces of it.
cnh1990 said:
USA it is more apparent when you travel in the left lane of the hwy that has a concrete barrier and the sound bounces of it.
HAHAHHA! That is how I stumbled upon the sound in the first place!
Well the trip into work today was uneventful... whatever I did seems to have worked. No more noise. I noticed the turbo was slightly subdued in sound too. I could hear it spool but not nearly as much. I will keep an eye on it and I will also try to get to those manifold bolts somehow. Just to be safe.
So quick recap, tightened all 3 of the #4 manifold bolts, and all 3 of the turbo to exhaust pipe bolts. All other exhaust bolts are tight (no EBPV), and all manifold bolts I can get to are good. I will keep an eye on everything though.
Thanks again for all the help guys. i really appreciate it.
Rich
Ya know, when I redid my manifold, I put it on, tightened all the nuts down "good and tight" (not like you could use a torque wrench) then let it sit overnight. I was probably too exhausted from fighting all those things while playing pretzel. Anyway, the next day, I went and could tighten them all a bit more. May mean nothing, but that is my proceedure for R&R'ing. Let it sit overnight and tighten it again, then fight the stainless lock plates.
Dr.Hess
Dr.Hess
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