Author Topic: 2-3K rpm Vibration (Read 6375 times)

Asterian · « **on:** September 19, 2012, 11:19:07 AM »

89' E30 M42 - running quiete good on all modes. Normal level of vibration on all engine rpm's, except from 2000 till 2800. Filling like some kind of resonance. As its most useful range when driving in city mode - its disturbing a lot.
Does anybody have an ideas? Thanks.

P.S. Vibration not depends of speed, present at all gears when driving, during acceleration and deceleration, not depend on clutch engaged or not, present on neutral.

DesktopDave · « **Reply #1 on:** September 19, 2012, 04:30:06 PM »

Check your motor mounts if it's only that RPM range. They're hydraulic - filled with a thick grease - if that goes away it'll make for more engine noise. They tend to 'flatten out' a bit when they're done.

Asterian · « **Reply #2 on:** September 20, 2012, 04:35:40 AM »

Quote from: DesktopDave;116027

Check your motor mounts if it's only that RPM range. They're hydraulic - filled with a thick grease - if that goes away it'll make for more engine noise. They tend to 'flatten out' a bit when they're done.

- thanks, what can I tell about mounts..
In fact seems that position of engine is Ok (I mean radiatior fan has proper location in relation to the fan guard), same time minor cracks are present on top.

I was trying to make a test with hand brake - in general its not sems that engine was moving excessively, anyway
- how far (approximately in MM or CM) engine suppose to move?
- which one will be better - worn original mounts or new e28'535?

bmwman91 · « **Reply #3 on:** September 20, 2012, 01:33:57 PM »

I highly recommend using stock mounts. If the current ones are dead, then new M42 mounts are the best option. I ran E28 535i mounts for years only because they were so much less expensive, but they made the inside of the car vibrate a lot and were too noisy.

Smeets · « **Reply #4 on:** October 18, 2012, 10:27:46 PM »

I actually have this same issue. It could very well be motor mounts as, mine look pretty darn flat. I have also been considering running the e28 engine mounts because of cost. $40 verse $180 is a huge difference. I'll order some when I do my control arms in the next few weeks and report back.

keflaman · « **Reply #5 on:** October 19, 2012, 05:41:30 AM »

I've done a couple thousand miles since installing the Rockauto mounts and am still quite happy with them.

http://m42club.com/forums/showthread.php?t=15004&highlight=Rockauto

Smeets · « **Reply #6 on:** October 19, 2012, 11:06:42 AM »

$37 each seems much more reasonable. If they are Supposed to fit our car, then I wonder why it has that tab that you need to grind down? Seems a bit annoying, but its easy enough to do.

wazzu70 · « **Reply #7 on:** October 19, 2012, 06:31:43 PM »

For what its worth M10 mounts are a direct replacement if you want solid mounts.

I ended up buying OE mounts because the solid mounts made the whole car vibrate like crazy.

Asterian · « **Reply #8 on:** October 22, 2012, 11:46:49 AM »

From time that thread was started I have installed vibration damper on driveshaft and OEM front silencer. I can tell now for sure that is no more vibration on 2 till 3 Krpm range, but vibration resonance exactly at 2800 rpm.
I still not bought new engine mounts, cause if it will not fix a problem, it will mean that 200$ gone for nothing. So desicion is not easy.

Meantime was browsing internet for "2800 rpm resonance" - most frequently this happens with M3, M5 and some Porsche. Causes were: "something with exhaust", engine mounts, chain tensioner.

For Rockauto - I'm not sure that will get it in Eastern Europe ).

OKTAY · « **Reply #9 on:** November 03, 2012, 12:29:23 PM »

I have exactly the same problem eversince I bought the car since from 2003. I have came a long way, changed the engine mounts with originals, AFM, plugwires and later on COP conversion, 4 pintle injectors, and lately an adjustable fuel regulator. Everything has helped and made the engine smoother but this 2800 rpm vibration still exist. I removed the driveshaft vibration damper and that didn't make any difference. This front silencer theory is interesting though. I still have the original (might be clogged) and causing the problem?

Asterian · « **Reply #10 on:** November 04, 2012, 03:07:02 PM »

Quote from: OKTAY;117360

I have exactly the same problem eversince I bought the car since from 2003. I have came a long way, changed the engine mounts with originals, AFM, plugwires and later on COP conversion, 4 pintle injectors, and lately an adjustable fuel regulator. Everything has helped and made the engine smoother but this 2800 rpm vibration still exist. I removed the driveshaft vibration damper and that didn't make any difference. This front silencer theory is interesting though. I still have the original (might be clogged) and causing the problem?

- Front silencer improved situation, but not solved.
Was You replacing chain tensioner?

bmwman91 · « **Reply #11 on:** November 04, 2012, 04:55:02 PM »

Any chance that your exhaust tip is rubbing on the rear valence? I have had that happen a couple of times thanks to the sort of temperamental hanger straps making it hard to position the muffler. When the exhaust system heated up and expanded, it would deflect enough to do it to me.

Asterian · « **Reply #12 on:** November 04, 2012, 05:18:10 PM »

Quote from: bmwman91;117387

Any chance that your exhaust tip is rubbing on the rear valence? I have had that happen a couple of times thanks to the sort of temperamental hanger straps making it hard to position the muffler. When the exhaust system heated up and expanded, it would deflect enough to do it to me.

Previously i had this issue. Rear muffler was touching rear strut lower bolt, but "vibration type" was different and its fixed few month ago.

318is91turbo · « **Reply #13 on:** December 12, 2012, 08:31:50 PM »

its a 4 pot.. and its the transition point of how your engine flows. i honestly love how mine does this.

Asterian · « **Reply #14 on:** March 30, 2013, 01:57:01 PM »

Halleluiah! Its solved just now. I just removed one exhaust mount made by welder which was almost directly transferring exhaust vibration to car frame. Conclusion - all suppose to be so close to OEM as possible.