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944 Vibration at 3000 rpm after water pump change

  • 1987
  • 944S
Mileage: 
169 445
Engine
Glenville, 
New York

I own a 1987 944S and have a vibration problem that I've had to take upon myself to diagnose.

At 3000-4000 RPM, I feel a severe vibration through the shift knob. I never felt any vibration until I had the timing and balance shaft belts, rollers, seals and water pump replaced by a local repair shop.

When I brought it back there to have them diagnose, they said that everything was aligned correctly. I didn't believe them, so I had the local Porsche dealer check it out, but they offered no solutions.

After doing a lot of research, I noticed that the alignment of the balance shafts can be tricky. I pulled off the belt cover, found TDC and have taken the attached pics. I think that the lower balance shaft is 180 degrees out of alignment. The "O" is not visible through the rectangular opening on the cover.

From what I understand, I need to remove the sprocket retaining bolt and cover and use a piece of wire to probe into each groove to determine the location of the woodruff key (I suspect the tabs on the back of the sprocket cover were broken off).

My question is, can I remove the sprocket retaining bolt without affecting the balance shaft timing?  Any help would be greatly appreciated.

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