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Engine vibration Issue

backcountry

backcountry

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Hello all! :D

Just purchased a new factory stock GM Good wrench engine and had it installed at a local shop.

My problem is with vibration while under acceleration. Engine runs fine at idle and while cruising at a steady speed. As soon as I hit the gas the vehicle starts to vibrate. :mad:

Please note: Prior to replacing the engine I did not have this problem. :dunno:

As far as I know, the new motor came with a harmonic balancer.

The shop that installed the engine did replace the clutch assembly and flywheel however. :confused:

While at a complete stop with the transmission in neutral; I rev the engine up slowly while watching the tach and checking to see when this vibration starts. It appears to start at approx 1000 rpm’s. It will then go away shortly and return at about 1500 rpm’s. It will then start to vibrate again and then go away shortly .thereafter and return.

If I had to guess; I would think it was the flywheel/clutch assembly that was out of balance. :thinking:

Any and all suggestions would be greatly appreciated!

Thank you!
 
Did you replace your engine mounts too, or are you still using the old ones?

And how bad is this shaking... like you can feel it in the seat, or shakes the whole truck rattle your brains dont bite your tongue shaking?
 
Thanks for the quick reply Jagged!

Yes, I did have the motor mounts replaced with Energy Suspension.

As far as the amount of vibration; it does not vibrate a whole bunch, however it does make the glove box and ash tray rattle. It almost feels like it is only firing on 7 cylinders. :confused:

One more note:

I do have dual exhaust, however I do not have a balancer/crossover pipe. Could the harmonics from the exhaust cause something like this? :dunno:
 
I'd check all your plugs/wires, make sure you are on all eight. New distributor with the new motor? I've had the 'pick-ups' crack and break just taking old ones out.

When you take the plugs out look closely at the porcelan on them- sometimes they can get a small crack in them either during instalation, or when they're dropping the motor in, and can cause similar results.....just some ideas, good luck
 
Thanks BoDapper!

Yes the distributor is new as well as rotor, cap and wires. The plugs are new as well; however your cracked insulator idea is excellent! I’ll replace the plugs and check it Out! :waytogo:


I am running the Accel header plugs. Any pros or cons on this plug. Also, anyone have any ideas as to a good spark plug. I do have Hedman ceramic headers, so as usually, I have clearance issues. :(
 
Energy suspension mounts are a bit stiffer than stock. Your new ones will transmit more vibration to the frame than a set of old worn out stock ones. Probably isn't your problem, but it could also be a factor.
 
No Problem-

Accel plugs are fine, it's actually what I'm running right now with some Edlebrock Shorty Headers- had no issues with them so far.

Did you have the headers installed after the new motor? Easy to crack an insulator when putting them on, the clearance is always a bugger with headers. :mad:
 
Yes, headers were installed after motor; however I had the same headers on my old motor.

Dude, I see that your from Montana, what a nice state! I bought a condo in Big Sky Montana last year. I love it their! :saweet:
 
Yeah, MT is awesome- Born and raised in Libby. Bought a condo in Big Sky huh? :waytogo:

The skiing is bitchin in that area......snow bunnies galore. :D
 
Could it bee??

Maybe the flywheel from your old motor was balanced different??--you didn't say what year motor you removed..some new motors are externally balanced,I'm not that familiar with newer stuff though..

A bent fan blade can cause a vibration,if its a regular engine driven style,and not electric..an exhaust pipe or header rubbing against the frame or body will make it vibrate like that too..my diesel makes the ashtray and dash buzz and vibrate at certain RPM's,I think its the exhaust that transmits it into the cab..

Good luck,hope its nothing serious!.. :crazy:
 
Thank you all for the excellent advice! Now it's time to get to work! :waytogo:
 
You can test plugs/wires by pulling one wire at a time while it's running. The one that doesn't make a difference in idle quality is dead for some reason.

In my experience idle quality will not be great too if a plug or wire is bad.
 
Try checking the tourque on your flywheel bolts as well as checking the proper length sometimes 1 wrong bold goes along way.
 
backcountry said:
Just purchased a new factory stock GM Good wrench engine and had it installed at a local shop.
Click to expand...

doesnt matter what the syptoms are. you paid someone else to do it, and it isnt right, TAKE IT BACK!
 
diesel4me said:
Maybe the flywheel from your old motor was balanced different??--you didn't say what year motor you removed..some new motors are externally balanced,I'm not that familiar with newer stuff though..
Click to expand...

all 2 pc RMS flywheels (save for the 400) are internally balanced. all 1 pc RMS flywheels are externally balanced. 1 pc and 2pc cranks have a different bolt pattern on the back. you cannot screw them up.
 
After running solid mounts and energy poly mounts in drag cars, I can tell you they will transmit vibrations like you describe. I would not be surprised if you can't find anything wrong. Usually these types of engine mounts have certain RPMs that will resonate vibs in the cab. It doesn't mean anything is wrong.
 
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