1.9 dCi engine vibrations when idle

[pw981]

2004 1.9dCi 120hp 83,000miles FRSH

I've had this problem for god knows how long now, since about 50,000miles? It has progressively gotten worse too!

What the problem used to be:

In winter (or a cold day - 15c or below), on cold startup, engine vibrates badly. Idle revs are smooth, driving the car is normal. Just when idling it is very shaky. Once the engine had reached normal operating temperature it was fine. Had it checked out under warranty back then. Engine mounts fine, all four injectors replaced. No difference.

Problem now:

External temperature warm or cold, engine vibrations occur whether the engine is warm or cold. Vibration is the same no difference whether the engine has just been started or anything. No difference if I've been driving 40miles on the motorway and come to a stop, or a short journey. No difference. Problem is random, 80% of the time it will vibrate, the other 20%, when it won't its most likely quite warm outside.

Diagnosis:

I've been told it could be one of the multiple temperature sensors on the engine, coolant temp sensor, fuel temp sensor. I disconnected the fuel temp sensor and started the car. No difference! not even a warning light or anything. . .

I've probably forgotten a lot of details which would need to be known for me to get any help, if so just ask! SOrry I'm typing this in a rush...

Anyone have any ideas?

Thanks

Phil

[IainMW]

Get your Dual Mass Flywheel checked out?

Renault have had problems with these on the Megane's

[AlexB]

Did you clean the EGR valve recently?

[pw981]

alexB,

I did 4,000 miles ago infact, completely forgot about that! The valve itself was clean, a bit of oily sludge in the inlet manifold area though and that was cleaned out. This hasn't changed anything though.

IainMW,

Thank you for the advice, any idea how a mechanic would check this out? I'm guessing it involves removing gearbox/clutch etc.. = £££

[AlexB]

Phil,

You wrote: "when idling it is very shaky". If it is the flywheel, then shaking is due to imbalance. There should be a way to distinguish between such an imbalance and fluctuating rotational speed, which would be an indication of problems with sensors or something else. I know that you are convinced that "Idle revs are smooth", but the fluctuations can be small and regular, so that they are hard to detect by a naked eye (or ear). As the mass of the rotating parts is large, then even small fluctuations may cause significant vibration.

BTW, does shaking stop when clutch is depressed?

Renault give a few suggestions in p.351 in this document:
https://meganedoksi.uw.hu/MEGANE_II/MR366MEGANE1.PDF

One may try checking cylinders for traces of oil or fuel, comparing thickness of carbon deposits, checking compression, checking performance of injectors, checking the fuel system, etc.

Temperature sensors may also be suspects, but then the glow plug light will be staying on for long. For checking the engine management system it makes sense to get an OBD reader, something like this:
https://www.obddiag.net/allpro.html
At this point my imagination stops, it's too late, I am afraid... Keep us updated. I'll write if anything else comes to my mind.

[pw981]

some more detail,

what used to happen: start car on a cold day, idle is smooth. drive approx 500 yards then stop the car with engine on (I was actually attaching my sat nav that time which was why i stopped) I hear a few relays (?) clicking around the glovebox area then all of a sudden the tone of the engine idling deepens and the vibrations start.

what used to happen and can still happen: for the first 2 miles or so of driving the engine idle is smooth. Turn the interior cabin fan off and the engine tone deepens and the vibrations start. Turn the fan on again and the engine tone changes and all is fine again. No other electics in the car can reproduce this effect (rear window demister, headlights etc) After a few minutes, this scenario will no longer happen and the vibrations will be there regardless.

Dipping the clutch does not make a difference to vibrations.

The above scenarios and dipping the clutch lead me to believe the flywheel isn't at fault? But I don't know.. it could be anything! I'm just a bit surprised how disconnecting the fuel temp sensor didn't throw any warning lights on the dash..

Oh also sorry alexB i don't know any french! I tried an OBD reader a while back but it wasn't working with my laptop - I tried the reader in a few cars which made me believe my laptop was not configured properly. I have since returned the unit but I may give it another go.

[terry_mccann]

I still think the best bet is the upper drivers side engine mount.....standard crap with Meganes...

[AlexB]

I see... It can be the ECU adding revs as a part of heating/aircon control algorithm. The difference in revs is barely noticeable (50rpm), but it can cause vibrations if something resonates. "Clicking relays" control the electrical heater located behind the plastic cover in the passenger (left) footwell. These relays are also controlled by the same algorithm.

Play with the accelerator to investigate this resonance further. It can be related to engine mounts, as terry_mccann says. Does it make sense?

... I hear a few relays (?) clicking around the glovebox area then all of a sudden the tone of the engine idling deepens and the vibrations start.

...Turn the interior cabin fan off and the engine tone deepens and the vibrations start. Turn the fan on again and the engine tone changes and all is fine again. No other electics in the car can reproduce this effect (rear window demister, headlights etc) After a few minutes, this scenario will no longer happen and the vibrations will be there regardless.

...

[IainMW]

IainMW,

Thank you for the advice, any idea how a mechanic would check this out? I'm guessing it involves removing gearbox/clutch etc.. = £££

Not sure?

My Megane was only the 1.5dCi and this too suffered from engine vibrations only at idle, my dealer investigated many things but never got to the bottom of the problem before I sold the car.
It had 2 new top engine mounts, a gearbox mount and a lower engine mount as well.

The last thing that was checked was the flywheel but this was found to be okay, how the check was carried out I have no idea but the delaer did say that one symptom of a faulty flywheel was a rattling/tickng noise at idle and that they had changed a couple on 1.9dCi Meganes, (which was a gearbox out job)

[stevefire]

IT;s EXACTLY WHAT IS HAPPENING TO ME!!!!!

1.9 dci megane 2004. 6 speed gearbox.
engine vibrates a lot when idling...and lately it is doing sort of rattling sound and it gets worse when pressing and releasing the clutch pedal....
Got to the mechanic and he told me I got a damaged flywheel. They've got springs on them and he said they get easily worn out after 50,000 miles...
He told me he already got to change about 5 megane with the same problem. Considering I live in Malta with 400,000 population that is quite a big statistic.

He suggested to stay with the noise and rattling until the clutch breaks down, since a LUK whole clutch kit including the flywheel is nearly the same price as a Flywheel on it's own (about 750 euros)

Any ways does anyone suggest a non-original renault part that is better than the original???? Because i'm not ready to spend nearly 1000 euros every 3 years or so!!! better putting them on another new car.

Thanks

Steven
Malta.

[synchro]

very similar happened to me too. Turned out to be the top engine mount in my case.

[pw981]

To update, even though I've now sold the car... I never fixed the issue and it didn't get much worse. It was definitely the flywheel in my case, as I had to change it because the ring gear was damaged by the starter motor. New flywheel --> no vibration! I changed the flywheel in June 2010, at approx 125,000 miles.

I have to say though, mine never rattled, so yours may be worse. I recall a Renault Technician telling me that he hasn't experienced complete flywheel failure on a 1.9dCi.