Bad vibrations

[Stevehose]

I have a vibration from 1500-3000 rpm either in neutral or under load. Worse of course under load. Not transmission because it does it with or without the clutch enaged. This is what I have troubleshooted so far:

Eliminated ps pump and ac compressor belts.
Alternator seems fine.
Fan clutch is new and smooth.
Water pump new and smooth.
Timing ok.
Fuel filter ok.
Air fuel mixture ok.
Carbs are synched.
Viewed flywheel through timing hole - no wobble and was cleaned when 5 speed installed
Viewed front balancer - no wobble
Cap and rotor good. Plug wires good.
Clutch/pilot bearing/TO bearing new.
All plugs firing.
I unhooked the exhaust mount from the tranny - no difference.

So this leads me to:

motor mounts? these are a couple years old. I loosened top nuts and not much difference.

coil failing? engine seems to vibrate more on accel than stable rpm.

The vibration is felt more in the car than from the engine compartment and is felt through the pedals and when the clutch pedal is up, through the shift lever.

Any other ideas on what to check?

 

[HB Chris]

I would suspect the center bearing. Guibo would rattle/shudder from a standing start. Maybe tranny mount.

 

[Stevehose]

Center bearing, guibo, and tranny mount all new. I spent hours aligning the driveshaft so there was no play between output flange and guibo when rotated. No vibrations from drivetrain - the vibration can be felt revving with clutch pedal pressed in, and at speed with clutch pedal pressed in there is no vibration if the rpms drop and the car is rolling....the vibration can be felt revving in neutral not moving too.

I would suspect the center bearing. Guibo would rattle/shudder from a standing start. Maybe tranny mount.

 

[Aussiecsi]

...oh , I thought the heading was about how Sean Penn must be feeling right now :-|

PS. Hope you locate the problem Steve . Cheers, Simon

 

[Peter Coomaraswamy]

Hi Steve, I am assuming you get the vibration when the car is still, in neutral and increases with the revs (if I'm understanding the thread). That would lead me to limit my searching to the engine only. Even with all the plugs firing you could have something in the ignition amiss especially if it's an "even vibration" and not something that can be attributed to fuel/mixture. Maybe pull the plugs and see what they tell you, hopefully not valve related. Sorry to hear, fantom problems just make for additional mental anguish-

 

[Stevehose]

Yes, it is felt in neutral when car is still, worse in motion so I also think engine.

Pulled plugs, all look good. While engine was running I pulled plug wires on each cylinder while running to confirm function.

Valves - adjusted a while ago, I had the head off so maybe worth a check if this could cause symptoms.

Frustrating indeed.

Hi Steve, I am assuming you get the vibration when the car is still, in neutral and increases with the revs (if I'm understanding the thread). That would lead me to limit my searching to the engine only. Even with all the plugs firing you could have something in the ignition amiss especially if it's an "even vibration" and not something that can be attributed to fuel/mixture. Maybe pull the plugs and see what they tell you, hopefully not valve related. Sorry to hear, fantom problems just make for additional mental anguish-

 

[Stevehose]

Maybe el Chapo can help me :-?

...oh , I thought the heading was about how Sean Penn must be feeling right now :-|

PS. Hope you locate the problem Steve . Cheers, Simon

 

[JFENG]

I had a similar problem in an E3 when I was in college. 500 miles later the front crank pulley came off. Bolts were loose. I'd do the following
(1) remove belts and check for play in bearings/mounts for Alt and PS pump (and AC if you have it).
(2) check your balancer again.

 

[Stevehose]

I've eliminated the ps pump and ac compresosr belts. Alternator seems fine. Shined flashlight on balancer while revving and it seemed ok but will check bolts, thanks.

I had a similar problem in an E3 when I was in college. 500 miles later the front crank pulley came off. Bolts were loose. I'd do the following
(1) remove belts and check for play in bearings/mounts for Alt and PS pump (and AC if you have it).
(2) check your balancer again.

 

[sfdon]

Compression test asap.

 

[Stevehose]

Yes, makes sense

Compression test asap.

 

[Lotuss7]

Steve

Illusive stuff. Clutch engaged and accessories disconnected seemingly narrows the search.

How long has the car been running in it current configuration without the vibration and what has changed, recently?

Don's thinking engine issue. Completely possible. Compression? Hoping not that...especially if the car has been running well for a while and this just pops? I'm guessing electrical. Timing, dwell,bad coil, points, condenser, electronic ignition? Yep...look there also.

Vibration seem to be in a narrow band. Guessing a miss. Hope it is that straight forward.



.

 

[Stevehose]

Car ran fine until and shortly after I did the 5 speed install. Then Saturday the symptoms started.

I have a slight leak from the coolant passage into the oil pan via a warped or cracked head (another saga I am dealing with) which is probably why Don is suggesting a comp test which is a good suggestion. Recently it checked out ok but will redo to confirm. This will be #1 tonight.

I have a 123ignition distributor so to eliminate that as a possibility I am going to hook it up to the computer and verify it is functioning as supposed to. I will also swap the coil. Plug wires are Kingsbourne and a couple years old in good condish. Plugs are good.

It does seem like a miss to me also, but I am going to loosen the tranny mount to see if that has any affect also. Loosening the motor mounts did not affect it.

Thanks.

How long has the car been running in it current configuration without the vibration and what has changed, recently?

Don's thinking engine issue. Completely possible. Compression? Hoping not that...especially if the car has been running well for a while and this just pops? I'm guessing electrical. Timing, dwell,bad coil, points, condenser, electronic ignition? Yep...look there also.

Vibration seem to be in a narrow band. Guessing a miss. Hope it is that straight forward.



.

 

[Sven]

Since you mention that it started after the 5 spd was installed -

1. Did you bend the trans input shaft while installing (if that is even possible)?
2. Incorrectly installed needle bearing, damaged or missing?
3. Flywheel or clutch pressure plate out of balance somehow?
4. Bad bearing in the transmission.

Some of these seem to be eliminated since you mention this happens with the clutch pedal pushed in....

 

[Stevehose]

Tranny has behaved fine for 2 weeks and is silent and shifts great. Install went smoothly with no apparent issues (clutch, pilot, release bearings). With clutch in this takes pressure off input shaft bearing, thus pointing to engine as the source yes?

I looked at the flywheel in motion through the timing hole, fwiw no wobble observed.

Since you mention that it started after the 5 spd was installed -

1. Did you bend the trans input shaft while installing (if that is even possible)?
2. Incorrectly installed needle bearing, damaged or missing?
3. Flywheel or clutch pressure plate out of balance somehow?
4. Bad bearing in the transmission.

Some of these seem to be eliminated since you mention this happens with the clutch pedal pushed in....

 

[rsporsche]

Steve,

haven't you had the head off recently?

 

[Stevehose]

Twice! First time I stupidly replaced the HG when I was doing a bunch of other items-font seals, oil pump chain tensioned, chain guide and tensioner etc. Then It started to leak coolant into the sump. No leaks into combustion chamber as I tested the coolant for exhaust gasses and the oil is clean.

So I pulled the head again and changed to an OEM BMW gasket - same deal.

So my head is either warped or cracked according to Don. After the first head redo I did a comp test and all was fine and I had no vibrations. After second redo the vibrations started a couple weeks later so not sure if it is related or not, I suspect this is why Don suggested another comp test which I will do tonight.

I verified the block and cam are all lined up at TDC.

Steve,

haven't you had the head off recently?

 

[rsporsche]

well you answered the first question - whether or not the cam is lined up correctly (i assumed it was). if it wasn't, that opens the door for a myriad of things that could cause the condition -

i realize you haven't run it very long, but can you tell anything from the color of the spark plugs - too lean or rich in one cylinder.

 

[Stevehose]

Plugs uniform and tan, AFR range is 12.5-14

i realize you haven't run it very long, but can you tell anything from the color of the spark plugs - too lean or rich in one cylinder.

 

[m5bb]

Steve,

When it's running is the exhaust full of white smoke or steam?

I suspect coolant in chamber and when at higher rpm it is fouling a plug.

Maybe hard to tell on plug just by looking at it.


I have an extra B34 head that was taken apart to rebuild but found an M90 head which was better.

Originally I said B35 head and that is wrong but now corrected.

Gary