Turbo Making A Rattle Sound

[barnoon]

Hey guys,

I have a R32 GTST with a RB20DET,

About 2 months ago I had my stock turbo changed to a 2nd hand turbo which had been hi flowed, I had it changed over at CRD and once I got it back I noticed straight away a strange rattling type sound that was coming from the turbo, I had this looked at by CRD and they said it was because I was missing 2 manifold studs. I put the car into another mechanic and had all the manifold studs gaskets etc replaced and got the car back yesterday and now its still making this noise!

Its kind of hard to explain but the car still boosts normal and doesnt make any strange squeels etc on boost but on idle you can hear a slight rattling sound coming from the turbo then if you rev it to 1500rpm or so on the rev down it does the rattle a fair bit louder, it doesnt make this sound at all revving up or when the car is on boost, only very slightly on idle or on rev down in neutral.

If you get under the car and listen you can hear the rattle go right down through the exhaust, I tried to locate exactly where the noise was coming from by putting a screwdriver on the turbo and listening with my ear on handle and I noticed its loudest on the wastegate arm rod thing, so im guessing its either the turbo is on its way out or that wastegate arm is loose somehow and needs to be tightened? Im fairly sure its not a gasket as all the gaskets are brand new and ive had a gasket go on me before and this sounds nothing like that.

Any advice greatly appreciated.

[Link]

bearings?

[barnoon]

Yeah it could be that is their anyway I can confrim if bearings are the problem without taking the turbo off?

[race_snooze]

take the dump pipe off and play with the exhaust wheel.

[barnoon]

take the dump pipe off and play with the exhaust wheel.

Ok and how does that tell me whats wrong with it? Sorry im not sure of these things...

[MANWHORE]

Tell me dave, is it a sliding performance highflow?

[barnoon]

Nah its a GCG hi flow

[MANWHORE]

Ok, because, if it's the actuator rod that's rattling, that means that it's most liekly the flap on the exhaust side.

one thing you can do to fix it, is either get an adjustible actuator like the hks one, or bend your actuator rod.

I wasn't aware of this, but looks like maybe gcg use a shorter catridge too like the slide turbos?

Instead of bending the actuator rod, i'd prefer to buy the adjustible. better do things the right way.

[R31Nismoid]

I bet its the actuator, it has all the tell-tale signs.

A few GCG's have done it now, nothing major really. Minor fix.

You just need to mod the actuator arm to hold the thing closed (if your on a budget)

You'll also notice an decrease in spool time as the wastegate flapper isnt "flapping" around... where currently its not being held shut at idle.

So you'll gain a lot of midrange you never knew you had

As above, i agree with MANWHORE. Get the adjustable actuator, and set your boost that way rather than a boost controller

Cheers.

[barnoon]

Thanks for all your help guys im going to get this actuator checked out and I hope this is what is causing this sound Ill update this thread with the news once I get it checked out but anymore advice on what it could be is welcome.

[barnoon]

Update:

Tonight I decided to see if putting a pair of pliers onto the actuator arm and pulling as hard as I can towards the front of the car does anything and the noise goes away 90% So im guessing this pretty much confirms this is definately due to the actuator? Will probaly explain why the car is fairly laggy.

[MANWHORE]

I have heard of slide turbos doing that, but it's pretty rare on gcg highflows. Did you supply them the actuator as well when they highflowed it? or did you pop it on afterwards.

I've had a couple turbos highflowed by gcg, and when I supplied the actuators, I didn't have the issue.

[R31Nismoid]

Some GCG's have done it.

Its like everything. If the actuator wasnt given to them, or isnt upto scratch. Its gonna flap around a little etc.

[barnoon]

I bought the turbo second hand and it didnt come with an actuator so CRD just used the standard one from my stock turbo as they said this was fine. Is it likely I will pick up more power once this problems fixed? Car currently has 200rwkw

[MANWHORE]

it's not so much the power issue. It will certainly be a lot more responsive. think about it this way. your trying to build boost, but the flap is flapping trying to let some out.

By having the flap functioning properly, it'll probably have less boost spike, and just overall be better.

[R31Nismoid]

Ah, you used a second hand actuator.

Thats the reason

You should pickup more response. Boost should build earlier/harder. No real "problems" will occur.

Just need it tuned

[barnoon]

Cheers fellas ill take the car to Unigroup Engineering tomorrow and have a chat to Yavuz and see if he can source a new actuator for me and put it on and give a touch up tune

[MANWHORE]

You don't need to pay someone ridiculous amounts of money to find a working rb25 actuator and tune the car.

the only difference, will be that the boost may be a bit different and your boost controller will probably need to be tweaked afterwards (flap will no longer be leaking).

Instead of getting him to source you one, pop up a post in the wtb section

Edited April 1, 2007 by MANWHORE

[23PSI]

I would say that the boys who are telling you it is the Actuator rod are absolutely correct, I had exactly the same problem after a hi-flow from Sliding - I also had sliding change the crack pressure on the actuator aswell. Naturally I was fairly surprised that their was a rattle after he had actually worked on the actuator. Thus when I was looking for the rattle - in similar fashion to old mate who posted this - disconnected pipe from dump to hi-flow cat and was hopeing to find remnants of the stock turbo - to no evail. I then decided to smack the rod with a hammer a few times - nothing - then got a jemmi bar levered off the block to slightly bend the rod - now the rattle has gone and their is no issue with the noise - though I do find the hi-flow to be quite laggy - which as I have read by others is fairly common with hi-flow turbs. Anyways Don't normally post much but this was just to similar to the situation I was in recently and couldn't help but reply.

Cya