Could my engine be unbalanced?

jimmy18thing · Sep 23, 2010

Ok had my bronco into the driveline shop to have all my angles checked after finishing my lift. They say all is well... T case is also rebuilt now. But when I am driving... Especially higher rpms there is a good vibration being felt. If I push in the clutch vibration goes away... Comes back once clutch is engaged... Is my flywheel, engine or clutch messed up? Help please!

itsabronco · Sep 23, 2010

pinion bearings was the cause of this same situation, exact situation, for me. is your rear yoke loose at all?

jimmy18thing · Sep 23, 2010

Rear diff was rebuilt last summer... The shop I had it in couldn't find anything wrong in my drivetrain

bax · Sep 23, 2010

Post a picture of your driveline angles.

itsabronco · Sep 23, 2010

Stick or auto? I also had an input shaft bearing on the trans that was the culprit on another vehicle. forgot about that one. it would vibrate like heck under load at freeway speeds. i would feather on and off the gas pedal and the vibe would come and go. it was a 4 speed

needabronco · Sep 23, 2010

Sit in the driveway and rev the engine up to 2200 RPMs, and see if the vibration is there? It's very possible that your clutch is mostly burned up and your flywheel is badly warped causing the vibration. If it's not there I'm betting it's driveline related, U-joints, pinion bearing/angle? Possibly something in the transfer case (I know it was rebuilt, but could be yoke related).

markperry · Sep 23, 2010

I believe he said he pushed the clutch in and the vibration went away

75bronco08 · Sep 23, 2010

so when you pushed the clutch in were you still rolling at the same speed?then it still can be a pinion angle it just not under a load.get a angle finder and post pinion angle along with drive line.did you have any vibrations before the lift?same wheels and tires?

addicted · Sep 23, 2010

I would get under the hood and slowly come up on the throttle by hand. Better yet, have someone else do it while you take a real good look at everything. Harmonic balancer, pullies, etc. Come up in RPMs at say 500 increments. Hold at each one and see if you can pin point noises and vibrations. It might be something simple so eliminate the stuff you can actually see and get your hands on before you start tearing into the clutch side.

needabronco · Sep 23, 2010

It could be possible that your balancer may have come apart or slipped causing a balance issue. Take a look at the balancer and see if the rubber in the middle looks out of place, or is missing?

addicted · Sep 23, 2010

markperry said:
I believe he said he pushed the clutch in and the vibration went away

Yea. Duh. I guess that might narrow it down a little. I need to practice reading the whole post before I jump in. Lol

Broncobowsher · Sep 23, 2010

Push the clutch pedal in and rev the engine, does the vibration come back?
Clutch out and in nuetral, rev to vibration speed and do you have a vibration?
Does the vibration only happen in a gear, multiple gears, or all gears?
Along the same lines, does the vibration follow the vehicle speed or engine speed?

Some of the questions may not apply, if you get the vibration sitting still then you know it is engine and not driveline for example.

When did the vibration start? Was it always there?
Is the engine original?

DirtDonk · Sep 23, 2010

addicted said:
Yea. Duh. I guess that might narrow it down a little. I need to practice reading the whole post before I jump in. Lol

Not so fast there young feller. Your description of how to check for engine vibration still holds water. Since we don't yet know whether jimmy18 let the engine rpm fall when he put the clutch in, or kept it up at running speed during the test.
So we have to stay tuned for that info. Then we'll know if any residual duh factor is still in force.

Paul

73azbronco · Sep 23, 2010

Yeah, those young whipper snappers!

jimmy18thing · Sep 23, 2010

I had it into the shop so I already knew it was my drivelines or angles. They went through all that after I put it in. Looks like the vibration still does it when I am in park and I rev the motor up... The Harmonic balancer looks ok... Unless it slipped and and is off some and I cant tell.... What else am I looking at? The clutch is pretty new. Centerforce... Stage II I think. I had the adapter housing bearing replaced with the transfer case rebuild also

73azbronco · Sep 23, 2010

so does it still do it when you rev and hold the clutch pedal in? rev with clutch out, yes, right? which would be wierd if it changed. Clutch pilot bearing?

Did it do this before the driveline work? Like me maybe you didn't notice before cause the driveline was so bad? Did it ever run smoothly?

Dampner slipped? wrong dampner 28 vs 50 oz? Wrong flywheel balance?

jimmy18thing · Sep 23, 2010

How would I know if it is the wrong dampner?

addicted · Sep 24, 2010

73azbronco said:
Yeah, those young whipper snappers!

Lol. Im 39. But thanks! ;D But back to the problem. The balancer needed depends on the year of the motor. One of the gurus will chime in on that. Seems to me that you would have noticed something like that right from the start. It doest "just happen", you know? I think the most important question is when did the problem start? The next one is what was worked on or changed just prior to it starting? If it started right after the lift and only happens when moving then it would be a really good chance its driveline related. U joints will "set" after they have been at a certain angle. They might not feel loose or sloppy but they will translate vibrations. And those vibration could feel different (better or worse) under a load, such as when you clutch in or out. But since you're saying it does it when you are just sitting and reving the motor, then you can pretty much rule out driveline angles and u joints. It just sounds a little confusing when you say you brought it into the shop to have everything checked out after your lift was installed. So....did the vibration start AFTER you installed the lift, or was it there all along? That info will really help to rule stuff out and narrow down the possibilties.

Ourobos · Sep 24, 2010

Did you use all three dow pins in the pressure plate?

DirtDonk · Sep 24, 2010

A couple of things come to mind. First, quadruple check your firing order. Depending on the cam, your engine could have 2 different firing orders. Doesn't matter if it's a 302/5.0 or a 351W either. If the cam has ever been changed, the firing order could have as well.
Yes, if your wires are off, you would probably feel the wrong running all the way from idle, but it's still worth checking, in case it's just one pair of wires off.

How long since a tune up again? Maybe one plug is not firing right and you're only feeling it at the upper rpm range.
Sorry if you already went over some of that. I haven't re-read the first page to re-familiarize myself with what's going on.

To eliminate the possibility that it's a driven accessory going bad, remove the belt(s) from the front of the engine and run it up again. If the vibration is gone, it's one of the front drive accessories.
Obviously, you can only run it this way for a couple of minutes since the water pump is not pumping, but it's perfectly fine to run it for a test.

Good luck.

Paul

Could my engine be unbalanced?

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