[Nitrouz boy]

Okay, I posted about this yesterday, and checked the archives. I was wondering if anyone has had this problem and can tell me what it might be.

between 1500-2000 rpm's the motor seems to vibrate, and then smoothes out until about 4500rpm's and starts a different type of vibration. Im not sure if this vibration is just the normal vibration on the turbo l28 motors. Can some of you tell me if your motor does this past these rpms? thanks. any ideas what the problem can be?

I did recently replace the clutch and pressure plate, but i want to check the easier stuff before having to pull the tranny out. Its kind of a bitch to do.

Thanks......NB

 

[john cross]

Just my .o2, and remember I am not a mechanic, but I think you are headed in the wrong direction. Vibration is caused by something rotating. So, first of all have you check your tires?/ Are they balanced properly? That was a problem on mine. Secondly, it could be the engine itself. Does this vibration occur when the clutch is in or out? Thaty will tell us whether or not it is the engine. These engines are naturally balanced, but that presumes that they are running properly. Especially with fuel injection, if one cylinder is more powerful than the next that will cause a vibration. On mine replacing the EFI connectors solved a number of vibration-related problems. With an EFI car, corrosion=resistance and the whole system is dependent on resistances being right. Corrosion in a connector will @!#$ up the performanc eof that connector. I suppose with carbs that this could be caused by uneven compression as well. If this vibration still occurs when the clutch is in, then it is not the engine. If it is not the tires, then it may be something more major. On mine it was; the engine not being properly tuned and electrical problems in the EFI, and the tires. Get back to us.

 

[Q]

Howdy.
The vibration you're talking about sounds suspiciously like what happens when the front crank damper cracks. I had that happen to mine and am just finishing up a complete rebuild because it took out my crankshaft.
It sounds like you have a harmonic vibration. If the front pulley is the culprit, pull the pulley bolt and see if you can remove the pulley from the crankshaft. The crack will be visible in the keyway of the pulley. If it turns out that the pulley isn't the problem, then start thinking about that flywheel. If the vibration showed up after you installed a new clutch, there is a possibility that a bolt or bolts have loosened up. That is a potentially disastrous situation. If it were me I would not even start the car again until I found the source of the vibration. You've got something loose in your rotating assembly.
Keep me posted as to what you find.
Q

 

[Nitrouz boy]

Thanks for the advice. just to clear things up the vibration occurs even while the vehicle is not in motion. and with or without the clkutch pressed in. Also I was paying close attention to the way the pulley turns and it doesnt flinch one bit. it appears perfectly balanced. Also this is not a big vibration, it does not vibrate much more than i would expect a car to at 4-5000 rpms, and one thing that just occured to me is that my tranny and differention mounts are now solid. there is no rubber in between, and maybe that is why i feel it more than usual. does this make sense?

I will definately check out the efi connections, goot tip. thanks guys

 

[Q]

vibration dampener

The deal is that the vibration dampener doesn't have to be wobbling around to cause a vibration. Mine looked as true as when it was new, but the crack was so bad that it eventually took out the front main seal and the damper got welded to the crank in a few spots.
Solid mounts could account for some vibrations coming through, and actually that is an easy test: did this vibration begin when you put the solid mounts in? If it did, then that solves the question and may you have no problem. If the problem appeared a while after, then you should keep digging.
Also, diff mounts won't transmit engine vibrations, though the transmission mounts might. What bothers me is that it isn't a constant vibration. I believe that this indicates a harmonic vibration in your rotating assembly.
You sure you bolted up the flywheel and pressure plate correctly?