M40 Engine annoying vibration

[chaz2005]

I've just bought a 89 E30 318i touring (UK spec) with the M40 engine and manual box, the general condition is good considering it's done 166k miles. I'm now working my way through all the known faults to make the car as good as I can get it.

I've known that since I bought the car about 4 weeks ago, it's had some vibration issues which I originally thought were related to the drive train ( as it's noticeable through all the gears) . However on the way home today I realised that it is actually the engine which is causing the vibes, as the vibes are even present when the car is stationary and the engine revved.

Sitting in neutral if you slowly rev the engine up, the vibration occurs at mid rev range, peaking at around 2500rpm, then improving again higher in the rev range. At 2500rpm I can even feel bad oscillations through the seat and it's also quite audible, sounds like it's really oscillating any cables or panels down near the footwell. If you then depress the clutch and do the same increasing rev test, the vibration is still there but noticeably improved, especially the noise factor.

I'm thinking it could be an out of balance or worn or poor quality clutch, faulty/incorrectly fitted flywheel or vibration damper or even something to do with the input shaft toe bearing, or even the crank shaft such as worn main bearings or end-float? Whatever it is, when pressure is applied to the clutch, it seems to affect the vibes, so this implies to me that it's stabilising the crank or clutch asembly helping to prevent that vibration movement somewhere....

Has anyone any ideas what this could be? or how to better check it out? I am wondering if there there any known problems like this, with this engine? I'll have a better look at the weekend, but I can see how this kind of problem might not be obvious by using eyesight alone. Also is there any sort of inspection plate to look at the clutch assembly?


(Have done about 500 miles now like this and no sign of it getting worse)

Any help would be appreciated.

Thanks

[jonbuoy]

Reading through your post there you seem to know what your talking about but i do believe the M40 has'nt got a drive chain.
Have you checked all of the engine mount's?
Doe's the engine rock when revved?
Is it a noise or can you just feel it through the car?
Is the performance sluggish?

Cheer's
Jon

P.s Welcome to the zone

[Gwynleym10]

Reading through your post there you seem to know what your talking about but i do believe the M40 has'nt got a drive chain.

Think he said drive train, not chain! slight difference.

Def check engine mounts, jack the engine up a bit and check condition of the rubber.

There is also a vibration damper which maybe loose

[rayman]

that kind of milage i would check gearbox mountins, prop uj,s rubber doughnut on prop.

[jonbuoy]

Reading through your post there you seem to know what your talking about but i do believe the M40 has'nt got a drive chain.

Think he said drive train, not chain! slight difference.

Def check engine mounts, jack the engine up a bit and check condition of the rubber.

There is also a vibration damper which maybe loose

Fair enough had miss read the post. Just making sure he knew that, no need for your sarcasm(sp)!!

[Martinaston]

may sound daft, but are you sure it's not a misfire ?