Alternator/Water pump belt vibration

[Stevehose]

Don I misread this and skipped the "start with fan removed" step but I did start it cold after removing the 3 belts. I have removed these belts at least six times in the last couple days and am convinced I could do it in the dark.

It seems there is a small amount of vibration between 22oo and 2800 rpm with all belts removed.

I also went to town on the alternator alignment, I bent the mounting ears so that the pulleys are aligned distance-wise and also verticle tilt, I used a 3/8" threaded rod and layed it into the pulleys to get it perfect after getting jiggy with the mounting ears with vice grips and a long cheater bar, so the alternator is now out of the equation.

So the engine runs smoother between those rpm's but it seems I have an underlying issue of a slight vibration non belt related between 2200-2800 rpm, I can feel it in neutral in driveway, coasting in neutral, and in gear - all at same rpm range.

Sven, I've checked for flush fitting etc, thanks.

So am I looking next at the crank nut, harmonic balancer, or something (hideous) else?

One other thing I am going to try is before I became aware of this vibration, I re-engineered the exhaust hanger attached to the tranny support, I am going to unbolt this to see if it affects anything. Any other suggestions welcome.

Start the car cold with fan removed
Remove AC fan belt
Remove PS belt
Fire it up and tell us what you see

Those fans I like are back in stock (15 bucks) at rmeuropean

 

[Stevehose]

**UPDATE**

Ok so my re-engineering of the transmission mouting bracket wasn't so great and I believe it is the culprit for transmitting the vibration to the block and into my foot.

I have the piece mounted between some rubber sections then to the tranny crossmember but the bolts aren't isolated so I must rethink this.

Good news is I've found the source.

How important is this exhaust mount?

 

[HB Chris]

I think the exhaust mount is important, you can buy the rubber bushings but they are not cheap.

 

[Stevehose]

But since it is 5 speed the bracket wont fit like the 4 speed so I'll have to figure something out

I think the exhaust mount is important, you can buy the rubber bushings but they are not cheap.

 

[bluecoupe30!]

Steve, pleased to read you are closer than farther away to resolution. I thank you for posting your symptoms, diagnoses, and tribulations. It is inspiring when the rest of us get these mysterious anomalies with our Coupes that ran great last week, and now have something crop up. We all have to stay on it, but it is easy to get discouraged. Reading about issues that gather such valuable advice and watching the progress is simply another reason I value this E9 Forum and its members so very much.
Best of luck! That Marie Leveau reference, just a bonus. Mike

 

[Stevehose]

Thanks Mike, I believe I have put the curse of Marie Leveau to rest for now, I put some cut up radiator hose in between the exhaust pipe and support bracket and sure enough runs as smooth as can be. This is only temporary as the rubber will surely melt but still, the "witch queen of New Orleans" has to go elsewhere for now! Triumphant sunset on the lake tonight as I throw her gris-gris into the water (and thanks for all the suggestions from this great forum):

Steve, pleased to read you are closer than farther away to resolution. I thank you for posting your symptoms, diagnoses, and tribulations. It is inspiring when the rest of us get these mysterious anomalies with our Coupes that ran great last week, and now have something crop up. We all have to stay on it, but it is easy to get discouraged. Reading about issues that gather such valuable advice and watching the progress is simply another reason I value this E9 Forum and its members so very much.
Best of luck! That Marie Leveau reference, just a bonus. Mike

 

[sfdon]

Throw it away.