[doughboy]

Originally Posted by nicktyler

I have been assured that there is nothing wrong with the turbos and the rattle is normal by a couple of different reputable sources. Not just the rebuilders.

What do you mean by finger trouble?

Finger trouble i.e. not set up properly.

How can the rattle be 'normal'?

They rattle if they're not tweaked to close perfectly at -200mbar rel. (IIRC), or if the vaccum system can't deliver the goods.

Both times mine wore and rattled, resetting them carefully to close at -200mbar sorted it.

If they're set to that and the vaccum system is OK then they won't rattle unless they are completely shagged.

Brand new no way, you never got new N54s leaving the factory with rattles, so new turbos shouldn't rattle either it's a nonsense??

[Josh1a1h]

Originally Posted by doughboy

This is nuts, how can new turbos rattle unless they aren't set properly? 100%.

It must be finger trouble?

When do they rattle? Start up (cold or hot)? Idle? Overun?

Rattles when it's cold. And once warmed up it still rattles but not as badly.

Remember when you also install Downpipes, the noise of the wastegates rattle is pronounced because the cats deaden a lot of the noise.

[nicktyler]

Originally Posted by doughboy

Finger trouble i.e. not set up properly.

How can the rattle be 'normal'?

They rattle if they're not tweaked to close perfectly at -200mbar rel. (IIRC), or if the vaccum system can't deliver the goods.

Both times mine wore and rattled, resetting them carefully to close at -200mbar sorted it.

If they're set to that and the vaccum system is OK then they won't rattle unless they are completely shagged.

Brand new no way, you never got new N54s leaving the factory with rattles, so new turbos shouldn't rattle either it's a nonsense??

I agree with all of this and it is only logical but I have been worn down to accept the current situation.

So this resetting. Do the turbos have to come off for this to happen? Can you elaborate on the 200mbar please? How exactly did you reset yours?

I did install downpipes and you can hear the rattle travelling down them when it is up on the ramp.

[Dirty Tool]

Would be nice to know how they are the actuators are reset.

Just been quoted 15 hours labour for the turbos

[nicktyler]

15 hours is a bit excessive but it is a massive amount of work. The book time is 8-10 hrs but that is if everything goes very smoothly. It might be their way of politley turning down the work as it is so much effort. I had a couple of garages that diddn't want to do it and the one that did said they hoped not to haev to do it again.

[gangzoom]

Mine has a slight rattle at cold when revs dropping from >5Krpm to below 3Krpm (all but un-noticiable unless your really listening out for it), but once warmed up it goes away.

On the move/driving have never heard any rattle, and I'm running AR Design high flow cats, so would expect some more noise than the standard setup.

Did a quick video a while back because I was considering changing the backboxes to see how loud the stock set up was. As far as I can hear there are no rattles at all from the wastegates (rev engine to about 5.5Krpm), all the various ticking noise etc I assume are normal for the N54 engine.

So I wouldn't consider a clearly audible wastegate rattle to be "normal", but are we all talking about the same noise?

[nicktyler]

That is the noise we are talking about on cold start. I have not got that anymore since the turbos were rebuilt. I do still have noise on the overrun and partial throttle.

[doughboy]

Originally Posted by nicktyler

I agree with all of this and it is only logical but I have been worn down to accept the current situation.

So this resetting. Do the turbos have to come off for this to happen? Can you elaborate on the 200mbar please? How exactly did you reset yours?

Originally Posted by Dirty Tool

Would be nice to know how they are the actuators are reset.
:

Ok....i'll try no to waffle to much...

The wastegates have to be set to close at a particular vacuum pressure and it has to be the same for both.

This needs doing for new turbos too at the time of fitment

The DME controls the wastgates by applying vacuum, it doesn't know the position of the wastegates it only knows how much vacuum it is applying, so the turbos have to be set to operate to a certain position at a certain vacuum, within a tolerance of course.

Both turbos also have to be set the same as there is only one common vacuum line to both turbos, so they have to react the same to the same vacuum or else one turbo will boost more than the other and you'll have problems like over / under boost, ocscillations, reduced power etc etc.

You need to take the downpipes off to do it, as you have to have finger access to the actual wastegate flapper.

It's a standard BMW procedure, but it needs to be done with a touch of finesse and experience of how tightly closed they have to be. Its not tightly closed, but closed just enough so you can still rotate the penny washer on the flapper between your finger - see what I mean? Until someone who has done it shows you its hard to describe...

Using a auto-vacuum pump (hand pump type) you apply the rated vacuum to each actuator in turn by removing the vacuum line to the actuator and putting on the line from the hand pump. You then adjust the actuator arms until the wastegate is closed correctly.

As the wastegate pivots wear, they don't close properly - that's why they rattle. So what you are doing is adjusting out the slack in the pivots.

You can only do it so much though, if they are really worn oval then that could be the end.

Mine have been adjusted twice with 100% success by Darren Woods and are still rattle free.

If whoever changed the turbo's didn't do this then they unfortunately haven't done it properly.

[nicktyler]

As replies to questions go that is about as good as it gets!

Cheers

Now I just have to find someone that can give it a go for me as Darren Woods is a bit too far away

[doughboy]

Who ever did the job for you should have a vaccum pump, they're a pretty common tool really these days.

I'll try to find the exact vaccum figure.

[Dirty Tool]

Originally Posted by doughboy

Who ever did the job for you should have a vaccum pump, they're a pretty common tool really these days.

I'll try to find the exact vaccum figure.

Many thanks!

[335DEE]

Not sure if it's the same principle , but post below is how i did a quick overall check on my vacuum system on my 35d .. http://www.e90post.com/forums/showth...ht=rVA0JNsFLWE

[phil200tdi]