[Andrei.v]

Hello . I have an Alfa Mito 135 Hp 1.4 Multiair. I just heard a few days ago a strange noise coming from my engine , when it decelerates. Basically i hit the gas pedal , and after 3-4k rpm i take my foot of the gas pedal , and the noise appears. I attached a link to the movie. Thanks

https://youtu.be/jRfGn1AFiUI

 

[Skaffen]

As no-one's replied yet I had a quick search through the forum archives

Seems it could be from the turbo - see these couple of threads which have some youtube clips of the sound and seem to describe similar patterns of when the noise happens:

http://www.alfaowner.com/Forum/alfa-mito/605089-turbo-rattle.html

http://www.alfaowner.com/Forum/alfa-mito/374808-135ma-gritty-sound-as-revs-drop.html

There seem to be several different possible causes if it is the turbo area (with the most expensive to sort being turbo bearings).

One of those threads links to this fiat forum where it seems it can be the actuator linkage with a potentially easy fix:
Technical: URGENT - Newly purchased sporting 135 multiair making strange ticking sound - Page 4 - The FIAT Forum

 

[bbadger]

My G has a similar sound but only when the revs have really dropped does it become noticeable.

Rev to 2k, let it drop then just as the engine comes to rest at idle there is a similar guiding noise for a few seconds from the turbo.

I haven't actually heard another multi air run properly so not sure what it should sound like but might go hassle the dealer soon.
The car only has 3.5k on the clock.

 

[Andrei.v]

Thank you for your answers. You helped me alot. It seems to be the Wastegate actuator. However if I choose the simple fix , it will not hard the engine ? Because basically we modify the turbocompressor overload.

 

[Skaffen]

I hadn't read through the link earlier in any depth - I just posted it as it looked relevant!

Having had a look I see it's adjusting wastegate preload, and certainly you wouldn't want to set too much preload as that would be bad (I'm not very knowledgeable about this sort of thing, but do know that too much preload is bad!).

On that fiat thread one of the posters did suggest that there was minimum preload set on some engines (perhaps suggesting the preload had been set to less than it should have been) so perhaps they amount of preload they added was fine, but that does sound a bit odd! It also raises the question of why it didn't used to rattle but has now started to rattle - probably best to speak to a turbo expert about it.

 

[bbadger]

I hadn't read through the link earlier in any depth - I just posted it as it looked relevant!

Having had a look I see it's adjusting wastegate preload, and certainly you wouldn't want to set too much preload as that would be bad (I'm not very knowledgeable about this sort of thing, but do know that too much preload is bad!).

On that fiat thread one of the posters did suggest that there was minimum preload set on some engines (perhaps suggesting the preload had been set to less than it should have been) so perhaps they amount of preload they added was fine, but that does sound a bit odd! It also raises the question of why it didn't used to rattle but has now started to rattle - probably best to speak to a turbo expert about it.

I just bought this exact thing up on a tuning thread in the G section.

i've done alot of reading on the dodge dart 1.4MA engines and they love adjusting waste gate preload.

Ive currently got about 16psi boost standard = 3 bars from full on the display = 8mm of preload.
Im going in to adjust this weekend and test the results.


But my concern is if the waste gate is rattling as such low revs e.g minimal boost pressure, something is surely wrong and in turn causing lower boost as it wont be seated correctly??
ill see if i can get a video tonight or tomorrow aswell.

Im a complete turbo novice but work on engine alot, so it just doesn't seem right in my mind.

 

[Andrei.v]

Thank you guys for the answers. bbadger , you said that you have 8 mm of preload. This was from factory , or you modified it? I just need to get rid of the noise , so I'll need maybe 2 mm . Excepting the noise the car rides extremely well . Indeed there were a few times on the highway when , at 3500rpm , the boost went down for a line and the came back up. I think is because of the same problem. As I looked in EPER , I did not find this actuator as a spare part , it only comes with the turbocharger. So alfa wants us to spend 1000 Euros for the whole turbo , only for this? I mean... what the ...

 

[bbadger]

The 8mm is stock.
If you have full boost showing already, im not sure you would want to up it any further, but maybe just check the tightness of everything anyways.
for non warranty work, im sure there is a good turbo repair place about, or upgrade to a hybrid turbo?

I just watched every video on all the threads Skaffen posted. I have exactly the same sound.
Trip to the dealers it is then....probably to get told "they all do that sir....its perfectly normal"

 

[Andrei.v]

) so when you look at the boost gauge , the boost does not go full ? That,s why you want to modify it ?

 

[EastUpperGooner]

Yeah I have this too, it's odd but as long as it isn't going to kill anything I'll live with it.

https://www.youtube.com/watch?v=W4UZjJG3jx4

 

[CalvinD]

Mine does it as well

 

[Andrei.v]

Ok so did aomeone modified the wastegate to fix this problem and the car is still ok? Because from what i read on the internet , is just a matter of time until the turbo or even the engine will fail. What is the safe setting for the actuator rod ?

 

[bbadger]

) so when you look at the boost gauge , the boost does not go full ? That,s why you want to modify it ?

Mainly yes!
But also to see if that noise will go away.

As an update.
Adjusted the preload, holding a steady 18-19psi now and the car feels alot "nippier" and smoother than before.
im still 1-2 bars off full boost.

Problem - the noise is still there and only when the revs drop...so im at a total loss.


Andrei.v - There is no right or wrong setting (well there is wrong) but adjusting the waste gate preload is all dependent on the boost level as this is what it will adjust, s over doing it will just throw the car into limp mode as the blow off is controlled by the ECU and will read any over boost as bad, cutting power to save the engine.

 

[rhenry95]

I had the same issue recently, had the preload adjusted a few turns for free by the garage...the noise has gone, the car feels sharper and I've had no issues at all in the last 5 months so worth a shot?!

 

[CalvinD]

I'm going to try it tomorrow and see if it makes a difference to mine.

 

[bbadger]

I'm going to try it tomorrow and see if it makes a difference to mine.

Just keep an eye on that boost level.

also a tip - stick a rag around the back of the turbo in case the C clip on the arm decides to try escape.
and remember 1 full 360* turn is 1mm preload.

 

[CalvinD]

Yeah I saw the rag tip in one of the videos on the Fiat forum, il definitely be doing that.

I think I'll try half a turn at a time and see if it makes any difference.

 

[CalvinD]

I've adjusted it by 2mm, the noise has been reduced but not quite gone.

The boost gauge goes to full then holds for a bit then drops a bar.

How do I know how much I can adjust it safely?

 

[bbadger]

I've adjusted it by 2mm, the noise has been reduced but not quite gone.

The boost gauge goes to full then holds for a bit then drops a bar.

How do I know how much I can adjust it safely?

Sounds like some good results then.
without knowing what your boost PSI pressure is, it would be almost impossible to say as the display on the dash is just abit of guess work i feel.


Did you see what preload you where at as standard?

 

[CalvinD]

Sounds like some good results then.
without knowing what your boost PSI pressure is, it would be almost impossible to say as the display on the dash is just abit of guess work i feel.


Did you see what preload you where at as standard?

I didn't check what it was before, just made two turns. Might try another one and see if it get's rid of it completely.