M3 E36 3.2 EuroSpec engine noise/vibration

[Torsen]

Hello to everyone,

I have some unusual problem in my M3, at least thats what the mechanic said. Before i'll give my car into their hands for a deep checkup i'd like to hear your opinion here.

It's quite simple : A vibration occurs while crossing 2500rpm either during deceleration either while accelerating. The vibration is rapid enough to make impression of a continuous noise. To describe the noise its like if you could hear a loud exhaust installation for a couple seconds (but the sound comes from the engine compartiment). For example the slower is the deceleration the longer and louder is the noise. To be perfectly specific the problem ranges from 2400 to 2600rpm ONLY. Anywhere else around there is absolutely no problem.

To answer any usual questions i'd say : There is noise whether the car is cold or warm, never had an overrev on it, an inspection was done lately. I could wonder if its related to the oil change because i notice the problem since (or at least have this impression) I put Castrol 10W60 (bmw guys advised it + there is special approval for M3 on it, so shouldn' be that bad) Finally i havent observed any power/performance loss... everything works fine except the noise and its certainly not normal (too loud and too specific)

I'd be greatful for any ideas

[Jared at Pelican Parts]

Hum, my E30 325is does this too. Only at 4000RPM.

[Torsen]

Any clue what could that be ? When did it appear in your car ?

[Jared at Pelican Parts]

Im suspecting my noise is coming more from the exhaust. I have heard of weird valve nises coming out of the M3 motors, I cant remember where specifically it was, but there was a post on the M3 board about this, explaining what it is.

[Torsen]

Well,

I have my car back from diagnosis and they said its probably the engine front flywheel (not sure if i translated it right). There are two other possibilities : clutch and the rear flywheel, both less probable, cuz they located the sound.

Anyone heard of flywheel problems ?

Anyways they said there is no immediate danger to drive whith with that noise but it wont get any better for sure. I guess i'll wait and observe, if it gets any worse i'll change it.

Just wondering how much would that cost in your area ? Here its around 800$ (job and the part).

T.

[Jared at Pelican Parts]

I think you may have heard it worng, as there is no front flywhel on these cars. Perhaps he was talking about the harmonic balancer?

[Torsen]

Actually i think its a question of my wrong vocab. He was talking about a flywheel, even showed me a 2d picture on the computer. From what he was saying its located in the front of the engine (how much in the front i don't know), basically next to the clutch. Then he showed my the rear "flywheel" (maybe thats why he called the other one "front") ,located in the back of the engine, which is supposed to absorb shock and so on, and which they think might be eventual third cause of the noise.
Maybe he just distingushed those two by calling them front and rear... I'm not expert, but there were definetly two internal wheels.

Anyways, did you hear anything about flywheel problems ? What can it cause in the long term if anything ? Wouldn't want more damage.

T.

[Jared at Pelican Parts]

Ok, I'm really confused now. There is no front flywheel. He is most likely reffering to the harmonic balancer as a flywheel. If i understand correctly you are saying that it is next to the clutch, which is at the REAR of the engine. The flywheel acts to 1. Provide the starter with a ringed gear to spin the enigne and start it, 2. To porvide a surface for the clutch disc to adhere to, thereby tranmitting power through the transmission, and 3. counteract the rotation of the crankshaft and make the rotation smooth.

[Torsen]

You're certainly right. Maybe i misunderstood the directions he was pointing to, plus i'm translating from french so....

From what you say, i understand the noise i hear is simply unsmooth rotation and it appears at around 2500rpm because that would be the frequency of vibration that simply makes noise. It all makes sense i think.

Now the question i'm asking myself is: can it do more damage anywhere else if not changed soon enough ? And secondly : is changing this flywheel a perfect occasion to change the clutch too in a way where this is the same location ? The labour would cost more or less the same.

T.

[Jared at Pelican Parts]

Si vous êtes bruit de vibration d'audition, il est possible que l'embrayage puisse être là-dessus est sortie, ou ce pourrait être un roulement pilote. Combien de milles sont sur la voiture ?

Sorry if it makes no sense, It's been a while since I've studied French

[Torsen]

Heh, très bien

You mean that the cluch could be loose ? And where is roulement pilote in this deal ? Can you fix it without changing parts, just screw it back ? .. i dunno, just wondering.

The car has 60 000 kilometers which is around 37000 miles... not much, it has 7 years but it was never run in winter (basically 5 months out of 12 every year just standing...)

[Javier at Pelican Parts]

Dude thats all Greek to me.

[Jared at Pelican Parts]

I was trying to say that the clutch pilot bearing may be bad, causing a high pitched noise at certian RPM's. The pilot bearing is used to center the transmission mainshaft into the flywheel. Although it seems unlikely this is the problem with only 37K on the clock.

By the way,

Je fais des excuses si mon assez espace libre français d'isnt. Je peux le lire mieux que je peux le parler. En outre je parle aux Canadiens français davantage que des Français. J'ai entendu que les dialectes sont très différents. C'est amusement pour obtenir la chance de la parler.