New Motor Mount, New Noise

[artbuc]

1999 Toyota Avalon V6, 138k miles

Installed new OEM front mount. Original mount was getting sloppy but had not failed. Rear mount and top dog bone were replaced at 85k miles with OEM. Tranny mount is original but looks perfectly fine. New front mount definitely reduces engine movement but I am still getting some vibration in steering wheel when stopped in gear.

But, when I put car in drive, I get a metallic clunk. This only happens if car has been in reverse first. Here is the sequence: P-R-N-D get sound. Back to N then back to D, no noise. How would a new front mount cause this noise? Thanks.

 

[TinyVoices]

Other mounts are showing age. This is why you only ever replace all mounts at the same time. One new tight mount will exaggerate the slop and age in the old ones.

 

[The Critic]

The mounts are binding. If the engine was moved/lifted to replace the front mount, this can sometimes cause issues. Loosen the mounting bolts for all of the mounts, rock the engine a few times (or start car and shift thru all of the gears), and then retighten all bolts.

 

[Trav]

+1 that was going to be my answer if you didn't post it first.

 

[artbuc]

You mean loosen bolts on the new mount, right?

 

[The Critic]

Originally Posted By: artbuc
You mean loosen bolts on the new mount, right?

Most likely, but you may need to loosen the bolts on all of the mounts.

 

[Oro_O]

I had this same drive train in another vehicle. HIt was smooth as new at 300k but I had to do all the following things to keep it that way. To evaluate a mount problem, put something like a coin or cup of water on the engine cover and manipulate the throttle cables (99 has cables, 02 went dbw) to how much it vibrates at idle and moves when shifted and revved. Consider these things:

a) If using the OE dogbone, be sure to peel back the thin dust covers on the sides to evaluate the center donut. Can hide a broken donut.
b) Check the previously replaced mounts.
c) Have you changed the plugs (due at 120k I think).
d) Check tranny fill and service with a T-IV compatible fluid of the original viscosity (don't use WS/Dex VI fluids like MaxLife. They will work, but not perfectly).
e) clean the MAF and IACV.

To evaluate a mount, remove the nut, lift the engine slightly and then try to manipulate the stud. It shold not spin or be loose. Do this on all of them to relieve stress as already discussed.

 

[artbuc]

Originally Posted By: Or
I had this same drive train in another vehicle. HIt was smooth as new at 300k but I had to do all the following things to keep it that way. To evaluate a mount problem, put something like a coin or cup of water on the engine cover and manipulate the throttle cables (99 has cables, 02 went dbw) to how much it vibrates at idle and moves when shifted and revved. Consider these things:

a) If using the OE dogbone, be sure to peel back the thin dust covers on the sides to evaluate the center donut. Can hide a broken donut.
b) Check the previously replaced mounts.
c) Have you changed the plugs (due at 120k I think).
d) Check tranny fill and service with a T-IV compatible fluid of the original viscosity (don't use WS/Dex VI fluids like MaxLife. They will work, but not perfectly).
e) clean the MAF and IACV.

To evaluate a mount, remove the nut, lift the engine slightly and then try to manipulate the stud. It shold not spin or be loose. Do this on all of them to relieve stress as already discussed.


Thanks. Yes, to all your suggestions except I do use Dex VI. Started using it when DII/III was no longer available (use M1 in PS). I have been very happy with it. Was using it long before I noticed steering wheel vibration. I also removed and cleaned throttle body which did not make any difference. I clean MAF sensor when I get a lean code which has not happened for many years. Cleaning IACV did make a difference as it was sticking but it did not reduce vibrations. Same with plugs. I read a white paper Denso presented to SAE where they presented data showing no deterioration in performance of iridium plugs until 200k miles which was their design goal. I believe they achieved that goal. Unfortunately, my rig takes dual ground platinums so I change them more often than 120k but never see any real improvement.

 

[artbuc]

Originally Posted By: TinyVoices
Other mounts are showing age. This is why you only ever replace all mounts at the same time. One new tight mount will exaggerate the slop and age in the old ones.


Interesting, I thought it worked the opposite way. That is, a weak mount overloads and hastens deterioration of other mounts. Replacing the weak mount helps the other mounts. But, I am often wrong which is why I spend most of my waking hours reading BITOG!

 

[artbuc]

Originally Posted By: Trav
+1 that was going to be my answer if you didn't post it first.


Just found this. I tightened new mount bolts while car was still jacked up (passenger side only) and still providing some support to engine. So, I am optimistic that you and Critic have solved the problem. However, I would like to understand more about this. Exactly what is happening when a mount binds? Also, this article talks about increased vibrations but how could a binding mount cause a metallic clunk going into drive? What is making the noise?

https://repairpal.com/engine-vibration-after-changing-engine-mounts-392

 

[artbuc]

Got rid of the metallic clunk, thanks to Critic and Trav. Didn’t mess with rear mount yet. This the one in the axle bearing carrier. I did discover that the dog bone was off by a half bolt hole with engine off and car on the floor. Adjusted bracket so now have no “at rest” load on dog bone. Have to wait until I get it up to temp (off fast idle) to check steering wheel vibration.

I do hear a rubber creaking sound when shifting from P or N to D or R. Do I need to do some more adjustments or is a normal breaking in sound from a new mount?

 

[Trav]

If you hear rubber making noise after a few days you probably need to loosen them again as the rubber is under stress, just loosen the bolts slightly, its enough.
Sometimes it helps to do this with the transmission in neutral and wheels blocked, you want the engine/trans to be relaxed in position.

 

[artbuc]

Originally Posted By: Trav
If you hear rubber making noise after a few days you probably need to loosen them again as the rubber is under stress, just loosen the bolts slightly, its enough.
Sometimes it helps to do this with the transmission in neutral and wheels blocked, you want the engine/trans to be relaxed in position.


Will do. Does it make any difference if tranny is in Park instead of Neutral? Engine running or stopped?

 

[Trav]

Engine off. In park there may be stress on the mounts if the car is on the ground or ramps, make sure to apply the e brake and block the wheels before putting it in neutral.
If the wheels are in the air then it makes no difference.

 

[artbuc]

Got it! [censored], have been chasing vibrations and rumbling for almost 10 years (since 3/1/08) and 56k miles since I replaced rear mount and dog bone. All this time problem was not properly seating mounts before cinching them down.

Feel pretty dumb but so glad to kill this issue before I take a long dirt bath.

Thanks again to Trav and Critic.

 

[LeakySeals]

Use some grease at install. That helps seating