Im getting a strange flapping noise under accelration...i cannot hear it until i get on the gas. Like anytime i start to build boost i hear it...or if i put it in high gear at a low rpm and you depress gas pedal all the way you can hear it....its almost like if you stuck somthing into a fan noise... its just odd i only hear it when getting on the gas...so i really dont think its anything wind realted...even though that what it sounds like

i do have a crack at the flange where the dumptube meets the wastegate....I do have my dumptube recirculated back in downstream...Could this crack be causing the noise...

normally i would think no since its only going to be leaking when the wastegate opens...but since its all connected to the exhaust downsteam it could be leaking at all times.

Ive done some searching and saw loose timing belts making similar noise....but my timing belt feels tight and it doesnt make the noise at idle or any other time besides when i put the motor under load...

Any ideas?

 

Has anyone experienced a leaking dumptube? that is recirculated?

Or a exhaust leak that made a flapping noise?

I really do not think its the timing belt...you would think if timing belt was loose it would also make noise at idle and cruising speeds....this only happens while there is load placed on motor...im really confused about what it could

 

is your bov not letting car build boost. what boost level does it occur at what is the whole build consist of. I have never had a "flappping sound when at wot. but a little more info mite help solve mystry.

 

its a peak boost kit...so tial BOv...BOv is working fine..

its just once you start putting load on the motor...it sounds just like youre sticking something in a fan... im thinking it could be the crack i have in the weld ( at the flange where dumptube meets wastegate) its a decent size crack i need to get it re tig welded.

i searched other people who had flapping noise and most people had loose timing belts, and it what hitting the timing cover...my timing belt is tight tho...and im sure if the belt was loose it would be making the noise all the time..

im really stumpped....Car runs great no issue at all besides that crack in the flange...

like on the highway if youre against the jersey barrier you can hear the flapping clearer...if i bog the engine like 5th gear low rpms you can hear it easier since the motor isnt making as much noise. it kinda fades in the higher rpms and i cant hear it. But it think thats just cause the turbo and exhasut gets loud its harder to hear... its just annoying as i first start spooling its making a flapping noise

 

well on the way home today the dumptube completly broke away from the flange....so my guess is that was the flapping noise....it must hae been coming from the cracked weld...

now my next question....im going to a specialty welding shop tomorrow morning that tig-welds..
do you think they will be able to weld the tube back onto the flange wihtout having too take the entire turbo off the car?


will they have to take the flange off?

i included a picture

 

whole dump tube has to come off to reweld. looks like it was cut a tiny bit off which probably added to the stress on the tube. that can be filled with rod however. now look for a good fab or machine shop that has a tig welder, take it in, weld, run again.

 

well the dumptube is recirculated....do i have to take out the entire ehaust and everything to get re-welded? can they just take the flange off. re weld it and then bolt it back on?

im trying to not have to take the entire manifold and everything off the car just to have it re welded

the tube has alot of bending back and forth since there is a flex pipe on there....im hoping they can take the flange off....tack weld it on and get it welded all the way around without having to take everything off the car.

is that possible? or does everything have too come off the car?

i cant take just the dumptube off since its welded into the downpipe

 

here is a better view when it was first done....i cant just take the dumptube off

 

i don't see enough room to get a tig torch in there at all 360deg. plus, do you really want to drive it like that? take it all off and run it down in another car.

 

OK so they took the whole downpipe and dumptube off and welded it...they mig welded it doesnt look that pretty but its a fix for now...i will eventually buy a new dumptbe from peak boost and just have it re welded into the flew pipe

Im still having the flapping noise tho so its clearly was not the exhaust leak making that noise.

A have no idea what it could be...the timing belt would make sense since i noticed the flapping noise does get louder with rpm... but the timing belt feels reaally tight.

I cannot replicate the noise at idle...nonly when im driving and i start to accelerate...and it increases with rpm...not louder but just faster... I am complety stumped.

since i cant replicate the noise at idle i have no idea what it could be?

 

why did you kill the beauty? any machine shop or fab shop would of had a tig. you simply take the pipe off and run it down. tig is also a LOT easier to get even penetration with on stainless and on top of that unless they switched out the wire in that mig to stainless you'll have a nice rusty weld soon

 

How long did your car work "normal" after boosting .. and what psi or whp are you putting down. did this problem start over nite. I would do a compression test. a hole in the piston or a bent valve sounds can sound like what you are describing. Check all the plugs for a consistant burn. once it starts is it when u start to go into boost and does it do it at all speeds. like at 45mph , 90mph, etc. do you have adj. cam gears?

 

are you absolutely sure you don't have a boost leak or exhaust leak somewhere? dry gasket, cracking elsewhere etc?

 

i really doubt its anything like a bent valve or hole in piston... it runs fine, idles fine, and accelerates fine...i have no problems building boost there are no misfires it really seems to be running fine

this is what makes me lean more towards a exhaust leak...but it got welded up today i looked over everything and everything seemed fine

i kind of noticed the noise to get louder as the car warms up....it doesnt have to be in boost either. its just as i start getting on the gas youll hear it..then youll hear it increase in speed as rpm goes up.

its really stumped me...i mean its running fine but i dont want to just ignore it....clearly something is not right.

the car is sleeved with darton mids and there o-ringed im running about 18psi...it was tuned at 385whp at 15psi... ive noticed this noise last year before i put it away for the winter but i assumed it was just the splash shields in the wind. im going to make a schedule to have it re tuned monday...i will just have to let him know about it im sure they will be able to pinpoint what it is much easier...since i cannot replicate the noise at idle i have no idea where it is coming from...im totally lost i have no idea whats making the noise...especially since the car runs fine....and i cant replicate the noise unless im driving

 

ohh and another thing i prob should mention....i changed all the spark plugs all cylinders 2,3,4 all where clean white porcelain. cyclinder 1 was just slightly dirtier. it wasnt clean white like the rest...there were no deposits it was just wasnt as white as the other ones

it seemed normal color...it was just odd how all three were super white and one was a little dirty

 

check all of your exhaust gaskets, really really is pointing that way, if you see any black tracers between the head/manifold or at any junction you will have found your problem.

still don't know why you killed a really nice downpipe at an exhaust shop. i doubt you even saved anything. the average fab shop would have charged you $20-25 to tig that with stainless

 

I think your right about a exhaust leak after hearing the whole description. I would make sure the WG is working properly.

 

that and how much vacuum does your engine have at idle and what bov spring are you running? go over the basics and make sure you didn't miss anything

 

Well they had to take the whole downpipe and stuff off...i wasnt happy at all about the weld job...but i need a new dumptube completly it had been re weleded twice... But for now its fixed at the flange..

Yea i will have to take a good look at the manifold and look for tracers like youre saying...

i have a peakboost manifold...it was the 2nd verison i bought the kit in late 2009

I didnt see any leaks when the downpipe was off...but then again i didnt really check the manifold at all...i will have to take a good look.

Im def thinking it sound like a exhaust leak too....jsut odd how i cant hear it at idle or replicate it...it must be a small leak.

Im going to have to take a good look.

At idle i get 21 for vacum without headlights on and blower off...

if i put headlights and heater blower on the car might drop to 20.3-20.5. but it never drops below 20 at idle

It runs really good just this annoying noise...it has to be a exhasut leak...it doesnt sound like a noise the motor could be making.

 

and im not sure what BOV spring im using...whatever comes with a TIAL 50mm. it came with the kit...i never touched the wastegate or BOV. just used the TIAl that came with the kit

 

i dont think it could be a boost leak either...since i build boost fine...and i can get it too make the noise not in boost as well

 

well for those trying to help out i apprciate it...verdict was exhaust leak.

Check out cylinder #3 on PEAKBOOST ramhorn manifold...CRacked all the way around

must have started small and progressivly gotten biiger till i was able to see and hear the crack at idle.

peakboost is out of buisness so i guess im screwed for warranty correct?

going to take it off friday and have a specialty welding shop tig weld it and redo the dumptube since it was mig-welded...hopefully they can grind that down and re-tig it.