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really bad vibration


Cole
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So i just rebuilt the entire engine and turbo and I'm still breaking in the engine and everything and what is wierd is once my engine speed is around 2500 rpm, it starts to vibrate really bad and gets worse around 3000 rpm. This is when I let the tranny shift up by letting off the gas (automatic). I was thinking it is a tranny problem since when I got it, the engine was skrewed over and the tranny was rebuilt around 3000 mi ago (no records to prove this happened from the last 2 previous owner) and I'm leaking fluid around from the dome (not alot, but enough to give me the suspicion that it wasn't rebuilt right). Am I on the rigth track?
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So i just rebuilt the entire engine and turbo and I'm still breaking in the engine and everything and what is wierd is once my engine speed is around 2500 rpm, it starts to vibrate really bad and gets worse around 3000 rpm. This is when I let the tranny shift up by letting off the gas (automatic). I was thinking it is a tranny problem since when I got it, the engine was skrewed over and the tranny was rebuilt around 3000 mi ago (no records to prove this happened from the last 2 previous owner) and I'm leaking fluid around from the dome (not alot, but enough to give me the suspicion that it wasn't rebuilt right). Am I on the rigth track?

 

Does it stop on deceleration?

 

Bill

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K. i think i foundthe proble. i think myv cat is rubbing the bottom of m car. so now i will wait until the xhaust cools down an then i will remove the exhaustand inspect for any scatches underneath. if tere is any, i will use a hamer and smash the heat shield till it is flat.once finished, will go for another test drive and go all the way down to 3500rpms. if any vibrations occur, iwill letu know. (when i firt got my car, igt wouldn't even let me go past 3k. tchat was when the engine about died.)
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--UPDATE--

So the vibration at 2500 was my cat rubbing the heat shield, but it still buzzes really bad at 3k. Any suggestions or comments? I will get a reply by monday from the shop guy who did my engine. He said he has done a couple g54b engines himself too. What is called? The bushing that has to be on the crank in order to use an auto tranny and if u want to run standard, you have to remove it? I should ask him about that too...

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if the exhaust is touching anywhere, it will vibrate something awful from a certain point, and not stop as long as you are accellerating. That should be an easy fix to bend a hangar back to where it was, and should be. I suspect one of your hangars is bent and pulling the exhaust against the body somewhere. Mine did it once when going under the rear crossmember. Tweaked a couple of hangars, and it stopped. That was on an exhaust that I removed from another car, and actually had parts of it from 3 different cars.
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If you have a 5 speed and the auto pilot bushing is in your crank you will destroy the thrust bearing. better verify that with him before you run it again. A quick check on crankshaft end play might help at this point.

 

Dad

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Something off the wall for you to check. Are either of your rear axle CV joints' rubber boots split and/or do you have a "CLICK" noise from the back of the car with the drivers window rolled down when you start moving away from a stop light?

 

If so, you may have a CV joint that's going bad which is causing your vibration problem.

 

I had the same problem at 2.85 to 3.2K engine RPM's regardless of vehicle speed. :wacko: It turned out to be the driver's side CV joint that went FUBAR. Replaced it and the vibs magically went away. :)

 

Originally I blamed installing a BS elimination kit for the drive train vibs until I replaced the drivers' side axle/CV joint. Now she drives down the road as smooth as a kitten at any engine RPM and vehicle speed.

 

Sounds crazy but it's true. :unsure: :wacko: :wacko:

 

For What It's Worth.

 

KEN

Edited by Starfighterpilot
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If you have a 5 speed and the auto pilot bushing is in your crank you will destroy the thrust bearing. better verify that with him before you run it again. A quick check on crankshaft end play might help at this point.

 

Dad

My car is a 4 speed automatic. But I did ask the machine shop today if there was an auto pilot bushing on the crank. He will reply tomorrow or so. But in the mean time, I will check my cv joints tomorrow since I have to get up early in the morning. I will update tomorrow.

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I doubt they will know what you are talking about unless they have pictures or they won't remember since they won't know what one is or does. It centers the torque convertor. You might be able to remove the 4 flex plate bolts and then push it up or pull it down then the bushing may be in there otherwise it will move up and down about quarter of an inch and since the bolt holes for the flex plate are sloppy and have no centering or alignment purpose the convertor will have an orbital pattern and cause vibrations when the engine is running not to mention its eating up your transmission. With the 4 bolts removed you should be able to spin the convertor since the stub on the end of it is pushed into the bushing.

 

Here's what it looks like

http://www.b2600turbo.com/flexplate.htm

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well I just go done with my test drive, and I do have a squeak that gets faster when I move faster. I also noticed that it only vibrates when it is in 2nd gear before it changes to 3rd. I also noticed that when I was driving it a little bit more aggressivly, the vibration died down a little, almost to wear it's like a good engine should be. but it got worse when I drove it this morning. The vibration is the same, it just lessend when I drove it hard.
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That can also happen when the parts get all sloppy and are about to go. That engine have oil pressure? You didn't say if it had balance shafts or not. Did those that rebuilt it know what they were doing?

I did get bse kit on it and he is quite knowledgable about these cars. Only one guy did the rebuild and he owns the sh op. He has done 2 g54b engines before mine.

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I do have oil pressure. When I'm going about 55-60 mph, my oil pressure is a little above 3/4 of the way up and when I'm idling, I'm just below the half way mark (running at normal temperatures).
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