R33 Gtst S2, Turbo Problem?

[Mitcho_7]

Essentially, my car is making a slight fluttering sound on light throttle when accelerating. I notice it mostly in 2nd and 3rd between about 30-60 km/h.

According to the aftermarket boost gauge, the car is not on boost when i can hear the sound (but you can hear the pod is starting to suck in air and the turbo is starting to spool though). The needle sits between about -10 and 0 when i can hear it. It might still happen when the car is on boost but i cant hear it because of the turbo spooling/ pod filter suction working a lot more.

The car is pretty much stock except for a full exhaust, gutted cat and pod filter with heatshield and stock airbox snorkel. It has the mod to select between between 5 and 7 psi boost with a switch. Recently installed a new split front/dump pipe and it is currently missing a bolt because one of them snapped when removing the the stock dump and the new one hast arrived. Have been driving the car lightly like this for a bit over a week and the sound was not occuring before about 2 days ago. Other info i though may be relevant is the engine, gearbox and diff oils were all recently replaced. Engine oil is motul 8100 5w40, gearbox is redline mt90 and diff is redline 75w90 gear oil.

Im one of those types that doesnt likeit when my car makes a sforeign sound that it hasnt made before, but i dont posses enough knowledge to be able to properly determine what the cause might be. Im sort of worried that the sound might be something to do with the tubro and its about to shit the bed or something.

Does anybody have any ideas as to what the sound might be or am i making a big deal out of nothing?

Thanks

[markdem]

im wondering if it could be an exhaust leak. does the flutter increase with rpm?

[duffinz]

Sounds like u may have a slight exhaust leak, doesnt sound like an overly big deal. Check around the dump when u start it up, make sure the remaining nuts/bolts are tight.

[DVS JEZ]

Is this a new car to u? Or has the issue just started to happen?

If u start to spool up then ease of the throttle u can intentionally make the car flutter.

Does this seem like what its doing?

[Mitcho_7]

I have owned the car for about 10 months, so its not new. It has the stock bypass valve so i would have thought that when you back off the throttle the bypass valve would open rather then causing the flutter from air going back through the turbo? however my knowlegde isnt the greatest on the subject.

Ithink i have just noticed the sound recently because of the fact that i havent been driving it like i normally do because of the missing bolt in the dump.

I cant really say if it increases with rpm because once they revs get a little higher it sort of drowns the other sounds out, but it may still be there.

When looking for a leak should i just spray something on the area where the dump bolts on to the back of the turbo and see if it bubbles when the throttle is open a bit?

thanks for your help so far

[markdem]

you can find most exhaust leaks without much aid. if you can hear it from inside your car, chances are you can hear it when standing over the engine bay.

Ithink i have just noticed the sound recently because of the fact that i havent been driving it like i normally do because of the missing bolt in the dump.

id start looking here first. good luck dude

[Mitcho_7]

had a look at the dump this afternoon and it doesnt seem to be leaking from there. I sprayed a bit of nifti on the gasket and it didnt buble. Plus every single bolt/ locknut is as tight as it will go except for the missing one which is one of the middle bolts.

[Bsa]

look for black soot. you sure its not turbo flutter? if its exhaust leak it will sound tinny so to say

[Mitcho_7]

so i still cant find any exhaust leak around the dump pipe and i can now hear the sound when im going along in any gear above about 3k rpm. Its not so much a flutter now, i dont really now how to explain what it sounds like...

[Mitcho_7]

Ok, so i finally got a new exhaust to turbo bolt and went to put it in, but when the bolt goes through the bole in the dumppipe flange it doesnt quite line up with the hole in the turbo flange. So if i try to bolt it in its going to get cross threaded and snap which will put me back to square one.

The other 5 bolts/ studs and locknuts go in fine except this one at the top.

Its a JJR split front/dumppipe which is meant to fit straight on.

How do i go about getting this bolt to fit in? I cant return the exhaust to just jap as i have driven with it, not knowing the the top hole didnt line up directly with the turbo flange. I want to get it fixed as soon as possible because the sound is starting to get a bit louder and more constant.

[GTSBoy]

Just push the hole over in the direction you want it to with a die grinder and use a decent domed washer.

[Mitcho_7]

I figured the hole will need expanding a little bit, but I dont have a die grinder. Is that something a car garage would have on hand. Im pretty sure the exhaust is stainless steel and the flnage is pretty think, so trying to use a drill is probably out of the question I take it?

[GTSBoy]

Yuh, stainless is harder to machine than mild, and it's a bad idea to try to use the side of a drill bit to open holes up in any material, let alone stainless. That's why mills were invented. But the bodgy mechanic's version of a mill is a die grinder, and nearly every mech shop should have one. Even a Dremel will do. But before you do any of that, here's another suggestion. Loosen off all the other dump bolts (and nuts if you have studs in the bottom two), then try to get the top bolt in while you have some wiggle. I was only putting my dump back on the other day. Found that when I had 4 or 5 of the bottom ones in, I couldn't make the top and middle ones closest to the manifold side start to screw into the thread unless I had a bit more slack on the other 4. Oh, and someone underneath to support the back end of the dump and give it a little twist to help the holes line up is helpful too. cheers

[Mitcho_7]

a mate and myself are gonna have a decent go at sorting everything out on the weekend but if i still cant get it sorted i think i will take it to a mechanic and get them to stuff around with it. Do you think i will need a new gasket between the turbo and dump, even though this one is only a couple of weeks old?

[AngryRB]

a mate and myself are gonna have a decent go at sorting everything out on the weekend but if i still cant get it sorted i think i will take it to a mechanic and get them to stuff around with it. Do you think i will need a new gasket between the turbo and dump, even though this one is only a couple of weeks old?

I think alot of those dumps off the shelf are crap, i had an x force dump which didnt fit well either at the turbo flange or even at the cat, i also had the split dump and it stopped my wastegate from opening, very cheap and nasty

I would get new bolts and nuts, and make sure you support the bottem of it when your trying to align the holes, and make sure you have the proper gasket , there are some cheap ones around that have paper gasket in the middle, the proper one is a steel one.

Edited January 26, 2012 by SliverS2

[Mitcho_7]

So I think the leak may have been located. When the cat was disconnected from the exhaust, the gaskets had a bit of soot on them (at both ends of the cat). New gaskets with gasket glue seems to have helped. Couldnt get the dump pipe bolts to bolt in to the back of the turbo though, no matter how many times my mate and I tried to move the pipe around from underneath and uptop to get all the hole lined up. Will be a job for the exhaust shop I think.

Thanks for everyones help.

[DVS JEZ]

If its Not leaking at the turbo then just leave it be.

So is the noise gone now?

[Mitcho_7]

Yeh, I can't hear the noise anymore at the moment.