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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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  #1  
Old 11-19-2012, 01:30 PM
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Scottji Scottji is offline
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Vibration after guibo/tranny mount replacement

I replaced the driveline guibo, CSB, and tranny mounts (replaced with M3 tranny mounts), and immediately upon starting the car have a slight vibration right at 1k-1,250 rpms, then it goes away, and picks up again around 1500-1800 rpms, and then goes away above that. It's not related to the guibo/CSB, since it happens with car completely stopped just by revving the motor, doesn't change whether in neutral or clutch engaged. Seems the same with the RPMs going up or down. Car runs like a dream, no loss in power or performance, just slight vibration at those rpms. No codes. Doesn't "rattle" or have other unusual noises (suggesting it's not exhaust related), just slight vibration noticeable in the cabin at certain rpms. I'd post a video, but I don't think you'd be able to tell through a video. It's not even noticeable to people who aren't familiar with the car (even my wife didn't notice it when she was revving the motor for me), so it's not too bad. But of course, I notice it since it wasn't there before.

I've double-checked exhaust hangers, support, and re-installed new exhaust gaskets (where the exhaust bolts up to the headers). Replacing the CCV (had to do it anyway) and cleaning ICV and MAF didn't have an effect. Intake boots all look good (about 18 mos new). Beisan Vanos Seals also installed about 18 months ago. Not able to pinpoint by looking in the motor compartment, or feeling around the exhaust from underneath with car running. Doesn't seem to be excessive vibration coming from exhaust, but hard to tell.

The likely culprit I keep going back to is the motor mounts (possibly compressed down if I accidentally jacked the tranny up too much, or damaged/pulled if floor jack sagged while supporting tranny?), but wouldn't vibration from MMs be consistent through all RPM ranges? Or could using M3 tranny mounts on a non-M cause this vibration? Unfortunately, I already tossed my old TMs, so I can't put them back on to see if it helps.

Other ideas? TIA

Manual tranny, 128k miles.
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  #2  
Old 11-19-2012, 04:15 PM
QAfred QAfred is offline
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WOW!...same exact thing happen to me. I too changed FCABs and tranny mounts (M3 tranny mount too) rear dif bushing etc and then noticed a vibration. I started thinking like you did...WTH did I do?
Anyhow, after weeks of thinking about it and analyzing symptoms, I dismissed it was due to my driveline repairs and started to trouble shoot as if it had nothing to do with my driveline work since it acted like yours, in neutral, push gas it didn't feel right. I had a bad vibration from 2000 down to 1800 RPM, especially on decleration, went away on acceleration...no vibration, no nothing- just ran good except for this wicked vibration on the decel.

After replacing all the vacuum lines behind the intake (two were cracked) and pulling DISA, ICV etc. and cleaning them, to no avail, I finally pulled the little vacuum line from the bottom fitting on the elbow on the intake tube- the one that goes down to the fuel pressure regulator- and blew into it with my mouth-since I am too lazy to jack the car up and pull Fuel filter cover without knowing something is wrong, and WALA, it had blow by.

I pulled the fuel filter cover off and found the vacuuum line was worn out, stretched, where it attaches to the fuel pressure reg. It was tight on the plastic tube, but totally loose on the fuel pressure reg side. Changed that vacuum line, and that fixed it.

BTW- I installed M3 motor mounts too, months ago, while changing leaking oil pan gasket. So I knew that was not it.

Last edited by QAfred; 11-19-2012 at 04:16 PM.
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  #3  
Old 11-19-2012, 04:33 PM
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Scottji Scottji is offline
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Weird. Don't think that's my issue since I wasn't working in the area of the FF or fuel/vacuum lines at all, but who knows?? Takes 5 mins to check, so I'll give it a shot. Thanks!
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  #4  
Old 11-19-2012, 05:01 PM
QAfred QAfred is offline
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Neither was I messing with Fuel etc., but as you know these symptoms are typically a vacuum leak. My next step was going to be the carb cleaner spray to check for intake manifold leaks.
I did all the work you did, except the guibo/CSB, mine looked fine, acted like yours in every way except RPM range was different when Vibe occurred.

That is why I find this remarkable and a little scary, since I got the vibration after doing the same job and I do not believe in coincidence or much of anything for that matter (Like an old supervisor I used to have on the B1 Bomber program told me- don't believe anything you hear and only half of what you see - LOL).

I just found the leak yesterday, took it for a test drive and all was good, I am hoping I really fixed it since I only drove it ten miles or so as I was out of work today and did not drive it.

If it comes back I will swap out the tranny mounts and report back, since that was the last thing I did prior to noticing this (FCABs and tranny mount) I did keep my old tranny mounts and will re-install if it comes back, but do not see how they could do it. I sized them up prior to install, and the new M3 mount was less than .100" taller than the old tranny mount and I took that as normal compression- due to wear- same as motor mounts, they were severly compressed, so these new tranny mounts should have brought it back up into original alignment spec with motor mounts.

BTW, all of our vacuum lines are 3.5 MM (.127 inches) but good luck finding 1/8th -.125" vacuum line anywhere. I ended up ordering silicone based tubing from E-bay- search for 3.5MM vacuum line and you will find it in blue and black colors...$10 for several meters (about 3 feet 6 inches). You can change all of your vacuum lines with that much tubing.

Please let me know if you find something different. I will do the same>

Last edited by QAfred; 11-19-2012 at 05:03 PM.
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  #5  
Old 11-19-2012, 05:14 PM
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Scottji Scottji is offline
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Thanks for the great info QAfred! I will keep this on-hand as I try to pin-point my culprit. It does sound like we ran into a similar issue.
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  #6  
Old 11-19-2012, 05:34 PM
QAfred QAfred is offline
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no problem...

BTW- if you are going to change vacuum lines, including the one inch sections on both ends of the fuel regulator vacuum line - not depicted in this photo. You need to know that #5 in the photo detaches from the back of the intake making it much easier to replace all of this vacuum line behind the intake. Just remove the electrical connector and pull toward you. see the clip on the ECS photo, once you get connector off just grab that end and pull to get it out. A real Bicth if you do not take that #5 off the intake...


Also, if you pull number 4 off of secondary air pump and blow on it, it will have blow by. Since #5, the electric switch, is open to atmosphere until energized. So do not try a vacuum or blow test on it since it will not hold. Just swap it all out.

You need to remove the pastic VCG cover and the fuel runner cover too. It is also easier to pull the plastic shroud around the brake system to access the cap, #9, and the tubing on the check valve, #6.

If I had to do it all over again, I would have bought more vacuum line and replaced the hard plastic crap, #3, with silicone vacuum line all the way from airpump to the #5 switch. As it stands now, I have all new vacuum line but 12 year old plastic tubing...on both this system intake tubing and the fuel pressure reg. tubing- not depicted.
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Last edited by QAfred; 11-19-2012 at 05:38 PM.
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  #7  
Old 11-24-2012, 01:47 PM
QAfred QAfred is offline
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Bump..........
I ran my car again, after initially believing I resolved my 2000 to 1800 RPM vibration issue, during deceleration, by fixing a vacuum leak at the fuel pressure regulator. While that smoothed out my rough idle a bit it did not eliminate my wierd vibration issue- even noticeable when pressing the throttle in neutral.

Since I did not know what else to check, I decided to re-install my old transmission mounts and remove the new M3 tranny mounts.

To my amazement, the vibration was removed, even when the throttle was depressed at idle, and the 2000 to 1800 RPM decleration vibration, while driving, was also totally eliminated.

The M3 tranny mounts were a little firmer and about .080" taller- not sure how the harmonics from the beefier rubber or how the height delta could have caused this vibration issue, but lesson learned here is to always back up to the last thing you did, even if you cannot believe it is a related issue, and do not install M3 tranny mounts in non M cars.:

Anxious to see if this works for you Scott!

Note: I did install M3 Motor mounts (about 18 months ago) and M3 RTABS (about 2 months ago) with no adverse effects. However, they were both recommended upgrades, the tranny mounts were not. Stick to OEM / Lemfoerder for tranny mounts!!!!!
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  #8  
Old 11-25-2012, 07:03 AM
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Scottji Scottji is offline
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Thanks QAfred. I had heard that the Lemfoerder M3 TMs were a stiffer "upgrade" but apparently at the expense of some NVH. I'll pick up some non-M TMs and put them back in and see if that solves my vibration issue. Frankly, I've almost gotten used to the vibration, but I'm sure it'll feel a lot smoother by going back to the OE mounts

Thanks again!
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  #9  
Old 12-19-2012, 08:10 PM
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Scottji Scottji is offline
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Finally got around to doing this and QAFred you are right. Went back to non-M tranny mounts and the car is smooth as can be once again.
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  #10  
Old 12-20-2012, 09:48 PM
QAfred QAfred is offline
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Great!
I think the M3 mounts being a little taller than the E-46 mounts pushed up on the back of the tranny and preloaded it at the Bell housing area slightly warping the flywheel, which is the engine balancer, thereby giving us the vibration we were feeling.

I noticed when I took out the M3 tranny mount, and put the E-46 mount back in place, that it basically slid in place between bracket and tranny with zero lift on back of tranny. It mainly takes torsional load and provides only minimal lift type support. The M3 mount pushed up on the back of the tranny providing too much lift.
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