Technical Audible rattle type sound when car starts accelerating at low rpms then stops

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Technical Audible rattle type sound when car starts accelerating at low rpms then stops

ruispeed3d

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First of all, Hey Guys.

First post here for me as i've been a follower for a little time now and i recently came a cross a problem that is driving me mad on my stilo 1.9 jtd 115cv.
For some reason my car rattles a bit when i, at low rpm, start accelerating and only stops when i can really feel the car pushing strong with no stress and the turbo pressure is there.
I'm not talking about that normal rattle type sound that all diesel cars make when accelerating, this rattle is somewhat louder than that and i feel is coming from somewhere else.
i have installed a turbo pressure gauge and noticed that it will make that sound until the needle hits around 0.5bar. bellow that the cars is sluggish and makes little to no thrust, above that it all feels normal and the car pushes good and the sound stops. It will continue to make the sound every time i decelerate and then accelerate again while there is that rapid turbo delay and then stops again. When i hit it hard the turbo pressure increases more rapidly and that sound becomes shorter.
In short i feel it makes the sound every time the turbo pressure is bellow that 0.5bar figure where the engine is working harder and vibrating a bit.

Is this something loose on my exhaust system? I took it to the mechanic to sort the exhaust leaks that i knew i had but that was not it. Maybe something gearbox related? that dual mass flywheel with 300 000 km asking for retirement or anything related. I must notice that my clutch and clutch disk is starting to slip and i'm in need of a new one.
What do you guys think about it? I know going to a mechanic is the best thing but until i find time to do it i wanna know your thoughts.

Best Regards. Stay safe and drive safe
 
Hi

300000 km on an clutch is very good, my 2.4 managed 248000 km's.

The dual mass is designed to absorb vibrations at spesific low rpm.
So it might be that it is now telling you to replace.
Part explain why at low boost press when rpm low, and not just little load.

Only test I can think off is if you drive at 0.4 bar and press the cluch does the rattle stop?
Also at higher boost and rpm when you press the clutch in?
 
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I was going to say it's either a loose exhaust shield or it's clutch related.

If your clutch is slipping then changing it would be the first thing to do. Make sure you change the whole 4 part kit (clutch plates, CSC and the flywheel). Flywheels can pack up any time but mine is on 206,000 miles now and really needs changing (if some parts-vendors can agree what Valeo kit is the right one for it..!) so yours is probably worn out too. Change the whole lot.

Ralf S.
 
Hi

300000 km on an clutch is very good, my 2.4 managed 248000 km's.

The dual mass is designed to absorb vibrations at spesific low rpm.
So it might be that it is now telling you to replace.
Part explain why at low boost press when rpm low, and not just little load.

Only test I can think off is if you drive at 0.4 bar and press the cluch does the rattle stop?
Also at higher boost and rpm when you press the clutch in?
Hi, thank you for your opinion.
About that little test you say i have done that several times when it started to make the rattle and it does stop every time. It only appears when it is in that low boost/low rpm state.
When it idles, it does not make the rattle and if i rev it, it still does not do it. At this stage i'm inclined to the flywheel as the whole clutch system needs replacement but i always had suspicions about my exhaust system, especially my exhaust manifold as in these cars they tend to crack or break bolts quite easily, and heard people say it makes a rattle type sound.
 
I was going to say it's either a loose exhaust shield or it's clutch related.

If your clutch is slipping then changing it would be the first thing to do. Make sure you change the whole 4 part kit (clutch plates, CSC and the flywheel). Flywheels can pack up any time but mine is on 206,000 miles now and really needs changing (if some parts-vendors can agree what Valeo kit is the right one for it..!) so yours is probably worn out too. Change the whole lot.

Ralf S.
Hi, thanks for your reply.
I share the same opinion, it has been on my to do list since i noticed it slipping. Right now it only slips if i push 4th really hard, it revs a bit higher for instances and then comes down and the car starts to take off but it will get worse quite fast, so i must start thinking about spending the money. I'll cry a bit in my sleep but i'll eventually get over it, my boy deserves it lool.
 
Knacked dmf would be my guess
Does the engine loose speed very quickly in neutral or clonk and knock a little when turning the engine off,?
Hi.
regarding the loss of speed, i think it does loose a little bit but i think it still fits in the margin of what we consider normal. The only thing i can say is that it is not quick, cause if it were i would totally notice it as i'm normally quite sensitive to these things. But that clonk and knock while turning the engine off is another story, that i can confirm he makes, like there's something loose under the bonnet. If i press on the clutch pedal while turning off the engine the sound is still present but is toned down.
 
Hello,

What about the 2 x engines mounts located underside ?
Their job is to limit the engine movment due to the torque reaction.


Cheap and worth the replacement, as it can solve a lot of vibration issues when coasting, under acceleration and decelertion. Mine seemed OK (still some rubber on it) but vibration filtration was long gone, due to rubber hardening (15 year old + head)


B.R
Sebastien
 
Hello,

What about the 2 x engines mounts located underside ?
Their job is to limit the engine movment due to the torque reaction.


Cheap and worth the replacement, as it can solve a lot of vibration issues when coasting, under acceleration and decelertion. Mine seemed OK (still some rubber on it) but vibration filtration was long gone, due to rubber hardening (15 year old + head)


B.R
Sebastien
Hi. Still did not give much attention to those mounts but they sure are on my to do list to fix. Maybe one of these days. Cheers
 
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