Bad motor mounts?

[Dom8706]

I have some vibration in the pedal and steering wheel that is rpm related. Not vehicle speed related. When i am driving ill put the transmission into neutral with my foot off the gas and the vibration will go away. Give it some gas while still in neutral and it will start vibrating. Car parked engine on and reving the engine with the throttle cable will make the quarter panel im leaving aaginst start vibrating also.

I am correct in my assumption that it seems like the motor mounts or could it still be something else? Want to make sure i am right before i start buying parts. Also, OEM motor mounts would be the ones to get yeah? I feel like poly ones would be too stiff.

Thanks!

 

[Yoter]

Sounds like it might be motor mounts but there also is the transmission mount. Seeing as you feel the vibration less when you are in neutral, you might also want to take a look at the condition of the transmission mount. Is your car a manual or automatic? It could also be flywheel related if you recently replaced your flywheel it is possible that it is not properly balanced.

Edit: just saw you have an 02 so it is most likely an automatic, in that case ignore what I said about the flywheel.

 

[mtbtim]

This video I made might help you out. To check if one of your motor mounts is all the way broken, have the engine running, lift the hood, set your parking brake, have your left foot on the service brake and right foot on the gas pedal. Give it some throttle while looking at the engine through the gap under the lifted hood. The engine should flex a bit from the throttle input but should not lift up any significant amount. If it does, one of the engine mounts is broken. Now do the same thing in reverse and you'll see the engine flex in the opposite direction.

For the trans mount, you'll have to get underneath the rig and do a visual of the mount and utilize a pry bar to flex the mount looking for cracks in the rubber or possibly full separation of the rubber from the metal plates.

You could also get under the rig and have somebody in the driver seat giving some throttle input while you watch and listen. Obviously you want to get somebody you trust and someone that isn't the primary beneficiary of your estate. :lmao:

You would not want to go with aftermarket poly mounts. Poly would be too stiff and transfer lots of vibration to the frame rails and make for a very noisy drivetrain. Stick with the OEM rubber mounts.

<iframe width="560" height="315" src="https://www.youtube.com/embed/g_4DiywsSbk" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

 

[Bad Luck]

To caveat on what mtbtim said about testing procedure: you will want to try that procedure in drive and reverse.

 

[Dom8706]

This video I made might help you out. To check if one of your motor mounts is all the way broken, have the engine running, lift the hood, set your parking brake, have your left foot on the service brake and right foot on the gas pedal. Give it some throttle while looking at the engine through the gap under the lifted hood. The engine should flex a bit from the throttle input but should not lift up any significant amount. If it does, one of the engine mounts is broken. Now do the same thing in reverse and you'll see the engine flex in the opposite direction.

For the trans mount, you'll have to get underneath the rig and do a visual of the mount and utilize a pry bar to flex the mount looking for cracks in the rubber or possibly full separation of the rubber from the metal plates.

You could also get under the rig and have somebody in the driver seat giving some throttle input while you watch and listen. Obviously you want to get somebody you trust and someone that isn't the primary beneficiary of your estate. :lmao:

You would not want to go with aftermarket poly mounts. Poly would be too stiff and transfer lots of vibration to the frame rails and make for a very noisy drivetrain. Stick with the OEM rubber mounts.

<iframe width="560" height="315" src="https://www.youtube.com/embed/g_4DiywsSbk" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Thank you I will do those tests today.

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[gamefreakgc]

If the motor mounts check out ok, look into a misfire or low compression. If you have a cylinder that's not firing regularly or has very low compression it will "lope" and cause the engine to shake in a rhythmic manner. Increasing the RPM's makes it shake faster until you are spinning fast enough it stops vibrating (normally over 2K RPM's). If that sounds consistent with your experience, especially at idle, it's worth looking into.

I had a 3.0L Pickup that was not firing on one of the cylinders when I got it so was only running on 5. It displayed symptoms similar to what you described.

 

[Dom8706]

If the motor mounts check out ok, look into a misfire or low compression. If you have a cylinder that's not firing regularly or has very low compression it will "lope" and cause the engine to shake in a rhythmic manner. Increasing the RPM's makes it shake faster until you are spinning fast enough it stops vibrating (normally over 2K RPM's). If that sounds consistent with your experience, especially at idle, it's worth looking into.

I had a 3.0L Pickup that was not firing on one of the cylinders when I got it so was only running on 5. It displayed symptoms similar to what you described.

The vibration is most apparent when the rpm is over the 2.5/3k mark. So it doesn't seem like that would be the issue but a compression test is on my list of things to do so maybe I'll do that this weekend just to see.

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[Dom8706]

I want to revisit this as I still haven't found the issue. Motor mounts look good and rpm jumps showed me the mounts are working properly. Transmission mount looks good. Visual check of the u joints and a twist of the drive shaft tells me everything seems good. Compression test results were all above 200.

It still seems to be rpm related. Could it be a pully? I'm not sure what else to check. Wheel bearing possibly?

 

[HiLife]

How do your spark plugs look? When were they last changed?
You should be running Denso/NGK dual electrodes spark plugs.

 

[Dom8706]

How do your spark plugs look? When were they last changed?
You should be running Denso/NGK dual electrodes spark plugs.

Plugs are good replaced them with NGK duals when I did the compression test. Previous plugs were in really good condition also.

 

[nathanroyse]

I have the same sort of vibration... i replaced my transmission mount and it helped a little bit, but i still get the vibration. might consider doing motor mounts next

 

[Dom8706]

I have the same sort of vibration... i replaced my transmission mount and it helped a little bit, but i still get the vibration. might consider doing motor mounts next

Hmm. Let me know if you do and if it fixes the issue. I might just replace the transmission mount since it is pretty easy. Motor mounts are a different story though.

 

[406_Runner]

Hmm. Let me know if you do and if it fixes the issue. I might just replace the transmission mount since it is pretty easy. Motor mounts are a different story though.

The exact same thing is happening in my 4th Gen. It also got worse once I put wheel spacers on. Maybe it's just normal but it's annoying once you pick up on it. Did you ever figure out what it was? My thinking is not broken, but old/worn motor mounts, which I imagine is more difficult to diagnose without taking them off