Rewrite: without any rambling¡K

Basically, I have this vibration that starts around ~3,500k rpm and the severity of the vibration increases as the RPMs increase. When I bought the car I just passed it off as worn u-joints, bearings, etc, and I knew I needed to replace the bearings. After replacing the wheel bearings, tie rods ends, wheels, tires, etc.. I notice the vibration had decreased considerably but a little remains. This past week I received my 96 Service manuals and decide to use the procedure in there to see if I can narrow down the source of the vibration. After going through the road test procedure and reving the car up to 6krpm while out of gear and the clutch pedal to the floor. I¡¦ve come to the conclusion that the vibration is RPM specific. I would think since I brought the motor up to 6000 rpm with no load that the source of the vibration has to be from the motor itself or from an accessory (AC, Pully, etc..) I wanted to know if there is anyway to isolate the vibration by either by-passing the accessories to see if the vibration stops. Maybe removing the belt?? I know the water pump is driven by the belt and I shouldn¡¦t run the car for longer then a few seconds without the water pump running..

The car has a LPE top end kit, head, cams, intake¡K Umm... He also had the block ¡§freshened up¡¨ , balanced and blue printed. The first owner told me he had a problem with the motor losing power around 5500rpm, and the power loss could be see on the dyno sheet as a huge dip in the graph. He said the power loss was from a defective after market Harmonic balancer. Which he (first owner) replaced... Hmmm.. Replacing the HB could be the cause??

He also replaced the clutch before I bought the car.

My problem is I have too many possible sources for the vibration and I can¡¦t afford to throw money at the problem. I want some help to try to narrow down the source.

List of possible sources of the vibration.

1. New clutch installed. Damage to flywheel from old clutch? What should I look for if I pull the trans?
2. U-joints, Still need to replace them. But I wouldn¡¦t feel a u-joint vib with the car not moving.
3. Input shaft bearing/bushing¡K Not sure about this one but someone here at work suggested it. ?????
4. The balancer issue. Since the LTx engine is balanced with the balancer installed and weight is applied to the flywheel. Is it possible to check the balance of the rotating assembly without having to pull the whole engine apart?? How does someone replace a LTx flywheel without having to disassemble the engine? I would think if you replace the flywheel you would have to rebalance everything? Correct???????????? See where I¡¦m going here¡K. ???? replace flywheel, rebalance¡K. all should be ok? If the engine is out of balance
5. An accessory on the motor. What should I look for to see if anything is out of alignment? I¡¦ve looked at the pulleys with the car running and I didn¡¦t notice anything wobbling.

That¡¦s all I know.. Still kind of pissed right now so I hope you can understand what I wrote this time.. :D Thanks for your help and any suggestions.

Using a French Win2k workstation... Thats why u see all the ASCII..

[Modified by Bluewasp, 5:40 PM 5/13/2003]


[Modified by Bluewasp, 11:10 PM 5/13/2003]

 

Blah......Blah...Blah.......so what are you saying?????
:confused: :confused: :confused:

 

Blah......Blah...Blah.......so what are you saying????? I'm lost....lost...lost...
:confused: :confused: :confused:

 

An issue here is that the w-pump will not be circulating coolant while the
belt is off. If I was determined to try running the engine without making
other arrangements for circulation, I would warm it up until the oil came
up to operating temp and then shut it down and let it cool with the hood
open. The oil will hold heat longer than the coolant. Once the water temp
was well down or off the guage, I would pull the belt and run the engine
briefly with no load. What I wouldn't want to happen is to generate enough
localized heat as to boil the coolant and potentially do harm.

uhm, were any pieces of the rotating assembly besides the HB changed
or modified when the engine was apart? Pistons, rods or rings changed?
Pistons, rods or crank deburred and polished?? If so, then an OEM HB
is no longer likely to have balance characteristics close enough to be
suitable for the rest of the assembly - it will need to be matched.

Ideally, matching would be done by rebalancing the entire assembly
but I think that there are shops that can do a passable job of replicating
the balance from one HB to another. Assuming that an owner went
to the trouble to have it done.

I hope the engine wasn't run long with the bad HB in place. That
scenario opens up a whole 'nother train of thought.

BTW - I'm a member of the camp that is uncomfortable about running
engines at or close to redline with no load.




[Modified by Slalom4me, 7:57 AM 5/13/2003]

 

He is (or at least he was) saying that he has a problem and
he has considered several possible causes. He didn't mention
it but since he is in Germany, English might be a second language
for him.

At least HE only posted once. Now it looks like he has decided to
pull his post - why do you suppose that happened.

(Where are the moderators, please)



[Modified by Slalom4me, 8:14 AM 5/13/2003]

 

English is my first language.. :D :D I’m just so frustrated that I wasn’t thinking straight.. .sorry.


I hope it makes some sense now..


[Modified by Bluewasp, 11:04 PM 5/13/2003]