engine vibration

[skysoldier173rd]

I've noticed that I'm getting a serious vibration in the engine just above idle, but smooths out at higher RPM. Is this the sign of a bad vibration dampener or are there other possibilities. Does same thing sitting in neutral or going down the street. The dampener appears to be shaking a little I've noticed.

[pimpston65]

Originally Posted by skysoldier173rd

I've noticed that I'm getting a serious vibration in the engine just above idle, but smooths out at higher RPM. Is this the sign of a bad vibration dampener or are there other possibilities. Does same thing sitting in neutral or going down the street. The dampener appears to be shaking a little I've noticed.

maybe its off balance, or not fully seated... or both!!!

[pimpston65]

Originally Posted by pimpston65

maybe its off balance, or not fully seated... or both!!!

hey skysoldier173rd. my dad is ret. 82 Airborne. thks for your service!!!

[TJ's Chevy]

Check the that dampner for sure. That'll cause vibration...also check for loose bolts in the pressure plate and clutch area...What engine?

[pimpston65]

Originally Posted by TJ's Chevy

Check the that dampner for sure. That'll cause vibration...also check for loose bolts in the pressure plate and clutch area...What engine?

bet your hope'n its a 6 banger!!!

[skysoldier173rd]

it's a 350 with 700r4. It runs excellent idling and very good upon accelerating, but vibrates just at one speed.

[Mackie]

Is the vibration while your standing still; not driving? Did the problem just start, out of the blue? Or did it come with an engine swap or rebuild?
Some possibilities are: missfire, loose clutch or flywheel, weak or broken motor mounts and the dampener (balancer).
I'll be watching this thread cuz I'm chasing this same issue in my 305 V8. It shudders between 1000 and 2000 RPMs.

[Vincenthdfan]

My original 283 in my '62 was buzzing just like that.

Mine did it between 2,200 to 2,400 rpms sitting still.

I isolated the trans, clutch, pressure plate, fan, water pump, harmonic damper basically everything I could think of.

My solution?? Pulling the motor and putting a new crate 350 in it!

I'm pretty convinced that the old 283 was just tired and had sloppy tolerances so it was time for a change.

It was no fun at all driving it with the vibe because it was right in the meat of the powerband you always drove at....I couldn't take it anymore.

Should be like a whole different truck when I get her all back together.

[WOLFMANmike]

im gonna say its a harmonic dampener .. make sure its seated on all the way ... also make sure that the lil keyway was put back in the crank before the dampener was put back on .. and lastly if these have been done. try buying a new one and put it on .. i will say it should not have any kind of wiggle to it at all when you are watching it run .. so i would tackle that 1st

[skysoldier173rd]

it's a 350/700r4 that I installed 5yrs ago. The vibration is just above idle and goes away quickly on acceleration. Sitting still or moving, same deal. This just started. Think i'll start with the dampener as I can see a little wobble there. I 'll post what it was once I know.

[mechanicalman]

Originally Posted by skysoldier173rd

it's a 350/700r4 that I installed 5yrs ago. The vibration is just above idle and goes away quickly on acceleration. Sitting still or moving, same deal. This just started. Think i'll start with the dampener as I can see a little wobble there. I 'll post what it was once I know.

Watch the fan belts to and see if you have one jumping around at the same time you get the vibration. If so, try tightening it.

But like previously mentioned, the balancer should not wobble at all.

[crazy longhorn]

Originally Posted by skysoldier173rd

it's a 350 with 700r4. It runs excellent idling and very good upon accelerating, but vibrates just at one speed.

I hear 350.....gen I or gen II? The 1st gen was neutral Balance(both ends).....the gen II, was neutral, on the front, but had the balance weight on the flex/flywheel. gen II, had a "detroit weight, on the flywheel. If you are gen I, balancer 1st gen(2 pc seal).....gen 2, 1 pc seal.....longhorn

[homemade87]

Are you sure you dont have a dead cylinder .I have seen people drive around and not have one of the cylinders not firing and never know it . It can cause weird vibrations at low rpm and smooth out at higher rpms . Easy check , just start pulling plug wires and see if any changes .

[skysoldier173rd]

This is a very strong running engine. It idles smoothly and comes on strong on acceleration. Just vibrates at about 800 rpm and smooths right out under acceleration. I will check, but doubt that is the problem.

[WOLFMANmike]

Originally Posted by skysoldier173rd

This is a very strong running engine. It idles smoothly and comes on strong on acceleration. Just vibrates at about 800 rpm and smooths right out under acceleration. I will check, but doubt that is the problem.

I still say its the harmonic balancer. The rubber in between could be old enough that its that it has allowed the outside weight aka the timing mark part of the balancer to spin . even just a bit would throw it into a vibration because as I stated before that balancer should not wiggle or wobble any at all if this is the case you also may not be in perfect timing with your engine if the outside of the balancer has spun because of weak rubber that's another thing if you have timed the engine with a moved balancer but then that's another issue later down the road right now just need to get a balancer on it that does not wiggle

[Vincenthdfan]

I thought the same thing with my 283 (balancer). So I removed it, started engine...still shook between 2200-2400...that's when I yanked it outta the truck!

[Shaky]

I had the outer ring of the balancer slip relative to the inner on my 292. It gave vibrations at certain rpm and then smoothed out at others. A new balancer fixed it up. This may be your problem I dunno.

I had a buddy who was a mechanic. He warned against using Gunk engine cleaner and other such things on the balancer since he had seen the outer rings slip on more than one occasion.