MAJOR VIBRATION IN 53 SEDAN

[Guest mamasbuick]

My 53 straight has a vibration issue at 45 MPH driving and at high rpm idle.

Possible causes already eliminated are: not the vibration damper, or generator.

The flywheel is mounted correctly according to the two drain

plugs on the torque converter. Would appreciate hearing from anyone who has had

a similar problem with their straight-eight. Engine was overhauled by previous

owner. Other than vibration, engine runs nicely. Thanks

Edited May 3, 2014 by mamasbuick (see edit history)

[trp3141592]

Hi,

Motor mount(s) shot? Different length bolts from torque converter to flywheel? Damaged fan belt?

--Tom

[bhambulldog]

Engine mounting pads would be my first suspect

[JohnD1956]

I would suggest removing the fan belts and running the engine for a few minutes to see if you still have the vibration. If not I would check your fan for damage first.

[avgwarhawk]

Tires are ok and balanced? U-joint possibly had gone bad?

[Guest mamasbuick]

Vibration issue update: engine motor mounts were replaced and the vibration has become less profound, but is still there at 40-45 mph. Tires were balanced, fan belt removed and tested, u-joints replaced in drive shaft as well as new rear wheel bearings.

Edited May 3, 2014 by mamasbuick (see edit history)

[TexasJohn55]

No fun. You will have to temporarily seperate the converter from the engine. I don't know if you can slide the converter back enough to clear the flexplate or not but you need to run the engine without the converter. If it is a balance problem, that will isolate to engine or converter. You may be able to support trans and slide back on bolts, then slide some spacers between trans and engine and snug back up after converter is clear, then run engine. If vibration goes away, try rotating converter 180* and run it. Mark converter to flexplate first before unbolting.

[60FlatTop]

I see from previous posts that the u-joint was replaced in 2010. What kind of history has the car had since then?

Bernie

[Aaron65]

Is the high-idle vibration when the car is stationary? If so, it couldn't be anything behind the torque converter in all probability.

Maybe a dumb question, but is it running on all 8? Sometimes it's not all that obvious, since in reality, each cylinder in a straight 8 is only contributing maybe 15 horsepower total.

[1939_Buick]

Is it road speed only related or engine RPM?

[TexasJohn55]

If vibration is engine or converter, it should show up at same critical rpm out of gear or in any gear, not just 45 mph.

If drivetrain related or wheels, it will only show up at critical road speed and less at other speeds.

If engine miss, it may be felt more or less with engine load and rpm and be quite variable.

If it vibrates out of gear at a certain rpm, that may correlate to 45 mph but would need a tach to confirm if vibration always shows up at same engine rpm.

[1939_Buick]

If vibration is engine or converter, it should show up at same critical rpm out of gear or in any gear, not just 45 mph.

Difficult to analyse with a Dynaflow. Easy if the car had a standard transmission

[Guest 53 Roady]

The drain plugs narrow the orientation but I think it can still mount 2 ways and one is wrong. If it weren't for the high idle I would suspect balance of the wheel mass. Maybe the wheels were balanced but the drums may be off. Keep us posted.

Pat