harmonics at 2-3k?

[MIKe30]

Put a couple more miles on the swap car today. Seems like I have some kind of harmonics developing, mainly between 2-4k. Mostly when coasting or engine braking. It was getting worse the longer I was driving.

The original harmonic balancer on the motor looked pretty beat up, so I bought another one. I told the guy (I'll have to look up the members name, I want to say SQBimmer) that it was for an obd2 s52, and he said ok - he'd pull the right one. Looked pretty similar to my old one, but in better shape.

Two other things come to mind when typing this. I never got my driveshaft balanced before throwing it back on... even though mix matched, I did line up the white dots as best I could.

Secondly, I'm not running a driveshaft balancer but I'm pretty sure I have one. Should I throw one on? Doubt it's marked and it's not from the driveshaft that's currently in the car, does it have to be in a certain way or can it go on in any orientation?


Motor seems to vibrate a lot.

frustrating...

[flyboyx]

disconnect the driveshaft from the transmission. run it a bit and rev it up. if you still have the problem, i would say the harmonic balancer is wrong. i think it sounds like it may be the problem anyway. try putting your old balancer back on and run it that way.

[Pudmunkie]

Often times rotating assemblies are balanced at the factory. I am not sure how BMW does it but...

Try reinstalling the dampener that came from the factory, You'll notice that it has material removed in certain places; I doubt the one you bought has them in the same spot.

[mazur]

disconnect the driveshaft from the transmission. run it a bit and rev it up. if you still have the problem, i would say the harmonic balancer is wrong. i think it sounds like it may be the problem anyway. try putting your old balancer back on and run it that way.

I doubt free revving it is going to do anything. You need load on the engine.


The only experience I have with the harmonics being out of wack is when I ran an aftermarket LTW crank pulley way back when. At full throttle, right around 3.5k the car would sort of whine. You couldn't feel it, though.

[So Live]

Harmonics scare me especially that whine mazurs talking about.

Is your CSB in good shape? Not reused or anything right? I had some pretty serious decel vibes and the new csb basically fixed it. Im not running the DS damper but i might try it next. Not sure if its just vibes from running through bolt poly mounts...

Keep us informed im interested in seeing what fixes this thing.

[bostonbmw]

Is this something that you feel or is it a noise that develops ?

[e30Rob]

what DS combo are you running? i had the same issue...new CSB and poof gone.

[MIKe30]

disconnect the driveshaft from the transmission. run it a bit and rev it up. if you still have the problem, i would say the harmonic balancer is wrong. i think it sounds like it may be the problem anyway. try putting your old balancer back on and run it that way.

While I understand everything is connected in one way or another, what does the driveshaft have to do with the harmonic balancer on the front of the motor?

I did put the original one back on btw, no change.

Harmonics scare me especially that whine mazurs talking about.

Is your CSB in good shape? Not reused or anything right? I had some pretty serious decel vibes and the new csb basically fixed it. Im not running the DS damper but i might try it next. Not sure if its just vibes from running through bolt poly mounts...

Keep us informed im interested in seeing what fixes this thing.

It's a new CSB. I paid somebody a few bucks to press it on for me, but I wouldn't say it was the best job ever. The CSB was real smooth turning for about 3/4 of a turn, then it had some resistance, then real smooth again. Just put it on and hoped it didn't make a difference.

Is this something that you feel or is it a noise that develops ?

Noise that develops.

what DS combo are you running? i had the same issue...new CSB and poof gone.

rear half is stock, front half is 325is from parts car, new csb, no dampener.

My dad swears it's a vacuum leak. Sounds like it's coming from underneath near tranny/exhuast/ds area. I'm probably going to play with this tomorrow. Too f'n hungover to do it now..

[Spaz]

It's a new CSB. I paid somebody a few bucks to press it on for me, but I wouldn't say it was the best job ever. The CSB was real smooth turning for about 3/4 of a turn, then it had some resistance, then real smooth again. Just put it on and hoped it didn't make a difference.

I'd start my search here, it should be smooth through the whole 360.

-Cam

[MIKe30]

I'd start my search here, it should be smooth through the whole 360.

-Cam

Well after posting I realized what a dork post it was. I had the car in neutral in my driveway and it still makes the noise, which elimantes the driveshaft. Pressing the clutch down does not make the noise go away or change either, so that eliminates the clutch.

I'm going to put her up on jackstands soon. I'll find out what it is soon hopefully. I'm thinking my dad may have been right about a leak, but not a vacuum leak. Perhaps an exhaust leak of some sort OR maybe my exhaust is barely touching something causing as resonating type whiste/noise (perhaps the sway bar?) It really is a tight fit down there...

[MIKe30]

just got under there. I fear the worst.

It doesnt happen when the engine is cold, but when it warms up the noise begins. It's coming from the very rear of the oil pan. Anyone ever have this issue, and what was it? Will try to get a video soon. fml.

[z31maniac]

Fuck! I hope for your sake it's not the worst. I'm just now (2 1/2 weeks later) getting over my disgust of the headgasket popping after 225 miles in the car.

Ugh.

[MIKe30]

seriously, I don't even know what to do right now. guess take it to a local bmw shop tomorrow see what they say. another fucking $70 towing this pile around. ughhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh.

[Spaz]

When you're letting it warm up, are you driving or just letting it warm up in a driveway?

Maybe try and eliminate clutch/flywheel/throwout bearing issues by letting it warm up without using the clutch.

Does frequency change with rpm?

-Cam

[MIKe30]

When you're letting it warm up, are you driving or just letting it warm up in a driveway?

Maybe try and eliminate clutch/flywheel/throwout bearing issues by letting it warm up without using the clutch.

Does frequency change with rpm?

-Cam

All in the driveway. last time was with me underneath it. This. Sucks.

What I can't understand is why it is only when it warms up. There is only the windage tray back there on that side of the pan right? I'll get a video today. Hoping it's something simple.

I can't imagine it making a difference but I used 15-40 dino oil when I changed the oil.