My car is a 2015 Peugeot 308 1.6 HDI 120 cv manual with 60.000 kilometers (37k Miles), scrupulously taken care of and maintained. I’m aware french brands aren’t popular at all outside of Europe, but I’m desperately hoping that someone knowledgeable might do a miracle and point me in the right direction.
Immediately after the last periodic maintenance performed in october I noticed strong but silent vibrations everywhere - steering wheel, gear stick and pedals mostly, both at idle and while driving. Accelerating aggravated the vibrations, and engaging the clutch didn’t have any noticeable effect. The entire external chassis was shaking badly too, but there wasn’t any unusual noise coming from under the bonnet.
During said service, the techs (official network shop) did replace the following components:
- Serpentine belt and tensioner;
- Oil and oil filter;
- Brake fluid;
- Air filter and fuel filter.
Right after picking up the car, the vibrations were unbearable, almost like an oversized electric massager was strapped onto the car and activated at full power, even with the car idling in neutral.
Long story short, after the official techs refused to admit there was any issue, my odyssey begun: I had my car checked by at least a dozen of reputable mechanics (or at least considered as such) and several attempted fixes later, the issue still persists - albeit greatly reduced. What has been done up until now:
- Serpentine belt and tensioner replaced for the second time: vibrations were noticeably reduced, but not eliminated. No issues supposedly noticed with the pulleys;
- One faulty injector - which didn’t raise any CEL - replaced and the other three serviced, no changes. Current correction values are negligible.
- Motor mounts (three in total) replaced: vibrations slightly dampened, still very noticeable in the pedals and gearstick;
- Battery replaced: no changes;
- Engine decarbonization (I’m aware it’s considered snake oil): no changes.
- Dual mass flywheel and clutch kit replaced: vibrations almost eliminated, some fine “buzzing” still noticeable in the floorboard, seats, pedals and gearstick at specific RPM. Replaced flywheel was in bad condition, with a lot of play and full of blackened debris.
Except for a moderate correction value of one injector, which was replaced, all the diagnostics performed with official Peugeot equipment were negative. Engine throughput is fluid and linear, rpm at idle completely stable.
The vibrations right now are concentrated in the lower part of the car, floorboard and pedals, and in the gearstick. They feel like a fine “buzzing” and are RPM dependent, 1500 and 3000 rpm being the critical spots (3000 being a multiple of 1500 could be a hint?) in any gear, and generally couldn’t almost be felt at all at idle, between 1600 and 2900 rpm and over 3000 rpm. Sometimes they’re more noticeable, sometimes they’re less evident. There’s no obvious aggravating factor - e.g. engine being cold or hot. It’s almost random.
The car otherwise runs absolutely fine: engine performance is flawless, acceleration is linear without gaps or hiccups until redline, and there are no unusual noises, not even when driving at the critical RPM ranges (~1500 and ~3000).
I’ll provide a final recap, for clarity:
- Vibration intensity after the first service: 10/10, everywhere;
- " " after serpentine belt and tensioner 2nd replacement: reduced to 4/10, mostly on steering wheel, pedals and gearstick;
- " " after injector replacement/rebuild: still 4/10;
- " " after engine decarbonization: still 4/10;
- " " after dmf and clutch replacement: 1/10, mostly on pedals and gearstick, critical spots 1500 and 3000 rpm, feel like a fine, noiseless buzzing.
Every mechanic I consulted throughly checked my car, but while admitting the issue is there, they’re stumped.
A couple of final thoughts: the mechanic who replaced dmf and clutch said that the transmission mount was still in good shape. Could it still be the culprit? Maybe the new flywheel is able to absorb the strongest vibrations, but the finer ones aren’t dampened by the transmission mount, visually fine but somehow compromised.
Could it be an internal balance issue? I can’t really fathom how an engine could be damaged during a simple routine maintenance, performed by official technicians at a very well known shop…
Does anyone encountered a problem similar to mine in their car? I’d greatly appreciate even the tiniest hint, as I’m quite desperate. I’m attached to my car, and I’m very reluctant to give up.