Vibartion when engine is running

[Mike Hall]

The bronco i just bought yesterday has a fairly bad vibration when the engine is running which even gets worst when you drive it. Could this be a balancer problem or maybe the wrong balancer was installed on the motor? I have had many other classic cars including my 454 69 camaro i have now and none of them vibrate like this bronco so something has to be wrong. Any info on this subject would be great.

Thanks
Mike

 

[Southerner]

Are the motor mounts secure?

 

[Mike Hall]

They seem to be bolted down tight. The motor does not rock bad when you gas it so i think the mounts are fine. I will check them out some more though.

Mike

 

[Southerner]

It could be your balancer, though, I'm guessing because I've never had that happen to me. What engine do you have; 289, 302, 351? Is it modified or stock, etc. Hopefully some engine gurus will give their .02 shortly.

 

[mustangmarty]

When the Windsor in my '76 van was vibrating like that, it turned out to be a spun balancer. I towed it home because the vibration got so bad that I was afraid I'd tear up the main bearings if I tried to nurse it home. New balancer fixed it right up.

 

[74bronc]

what engine is it? Did the previous owner recently do some engine work? It is easy to mismatch components on the SBF which would give you a nasty vibration like you describe.

 

[1975stroppebaja]

if it's a newer 302 matched up to an older transmission, you might have the wrong imbalance flex plate/ flywheel. I believe '81 and earlier 302's use 28oz and '82 and newer use 50oz.

 

[Mike Hall]

Its a 302 from what he said but i guess it could be a 289 though. As far as i can tell the balancer has not been removed lately. When driving it does have more vibration and when you push in the clutch the vibration gets even worse. Im sure the wheels are out of balance and the drive shafts might have some play but i also think the engine has some bad vibrations coming from it being when its not even moving it shakes bad.

Mike

 

[74bronc]

the first thing I would do is make sure each cylinder is firing. A common cause of an engine vibration is that it is really hitting on only 7 out of 8 cylinders. Start there.

 

[Southerner]

While your checking everything out. Go ahead and write down your engine block cast numbers. They are located right above the starter on the passenger side. Some people say they can see them without removing the starter, but, I had to remove mine. There are several websites that will decode the cast number and tell you exactly what you've got. Hope this helps.

 

[Jeepster]

Some people say they can see them without removing the starter, but, I had to remove mine.

If you lay on your back looking up at the starter, between the block and starter, you can see the #'s on the lip of the block facing down towards the ground.