5th Gen Motor Mounts

[Lukkon]

Hey everyone,

Anyone here experience a failing motor mount on your 5th Gen 4Runner? If so I have a few questions:

- What were your main symptoms?
- If they were bad, did you replace them yourself or at a shop?
- If at a shop, what did the repair run you?

Reason for asking is I’m trying to chase down a strange vibration. I can feel it in the floor boards and is only really noticeable when coming to a full stop and when revving the engine in park/neutral. Also hear a notable clunk from the front passenger side at lower speeds and when shifting between drive and reverse.

So far, I have:

- Looked over all the suspension components and have not found any issues. Truck was aligned recently.

- Inspected exhaust and verified it is not touching any of the skid plates.

- Front rotors and pads were replaced last month

- Drive shaft and slip yoke have been greased all throughout

Initially didn't think it would be a motor mount at 142k miles but I guess anything is possible. The more I listen to it, it’s definitely pointing at signs of a failing motor mount but just wanted to see what others think or have experienced.

Thank you in advance!

 

[EddieV4runnin]

Usually I check for bad motor mounts by power braking the truck and feel a jolt/vibration. You can have one motor mount not jolt in drive but not in reverse. Try both and see that you find. If you’re able to duplicate it in Park/Neutral it should be easier to figure out what’s causing your concern. I would also make sure all your mounting bolts are torqued to spec.

 

[flyrv9]

First I'd check if any of the balance weights are missing from the drive shaft. The old way of checking for a broken motor mount is to put the car in drive and and add throttle with your foot on the brake. Have someone else outside to look and see if the engine lifts. Do the same in reverse for the other mount.

 

[Lukkon]

Usually I check for bad motor mounts by power braking the truck and feel a jolt/vibration. You can have one motor mount not jolt in drive but not in reverse. Try both and see that you find. If you’re able to duplicate it in Park/Neutral it should be easier to figure out what’s causing your concern. I would also make sure all your mounting bolts are torqued to spec.

Thank you for the input! Have to try the rest of holding the brake and revving the engine in drive or park to see what the result is as well.

I was also thinking that maybe the bolts just aren’t torqued but not sure what would cause this. Then again anything is possible.

 

[Lukkon]

First I'd check if any of the balance weights are missing from the drive shaft. The old way of checking for a broken motor mount is to put the car in drive and and add throttle with your foot on the brake. Have someone else outside to look and see if the engine lifts. Do the same in reverse for the other mount.

Hmm haven’t thought about the driveline weights only because if I’m cruising on the highway or anything above 10-15mph the truck feels great, but thank you for the suggestion.

I will have to test the truck the way you stated though. I initially only revved it in park and didn’t see too much play but I can see how putting it in gear would help show any play in the mounts.

 

[Lukkon]

Here is a video clip of the engine mount tested mentioned above.

1. Started the truck
2. Put in Drive, held the foot brake.
3. Revved to about 1500 RPM
4. Repeated steps but in reverse gear

Looks like there’s a decent amount of play.

Link: iCloud

 

[Jivewalker]

Here is a video clip of the engine mount tested mentioned above.

1. Started the truck
2. Put in Drive, held the foot brake.
3. Revved to about 1500 RPM
4. Repeated steps but in reverse gear

Looks like there’s a decent amount of play.

Link: iCloud

Make 2 new videos. focus camera on the RH engine insulator and then the LH. I didn't hear any noise like fan hitting the shroud or anything. Can't comment on play because i have no reference. 2 videos should show how mounts are acting under loads.

 

[LandCruiser]

The motor is supposed to torque on the mounts and even make the truck sway a bit under throttle but it shouldn't wobble back and forth after that.

 

[flyrv9]

Agreed - the motor should move a little from the torque and play in the rubber in the mount. But it should not lift up. I'd think a broken mount would be a rare occurence usually caused by a rather large jolt - like a big pot hole.

 

[Jivewalker]

The motor is supposed to torque on the mounts and even make the truck sway a bit under throttle but it shouldn't wobble back and forth after that.

Agreed - the motor should move a little from the torque and play in the rubber in the mount. But it should not lift up. I'd think a broken mount would be a rare occurence usually caused by a rather large jolt - like a big pot hole.

In looking at the construction of the assembly, it's possible that one of the mount bolts could break, be loose, or the insulator could wear or break? I would inspect those mounts and insulators carefully to rule them out. OP says he hears a noise and feels vibration when idling/revving. I think mount is possible, hopefully not engine issue.

 

[Lukkon]

In looking at the construction of the assembly, it's possible that one of the mount bolts could break, be loose, or the insulator could wear or break? I would inspect those mounts and insulators carefully to rule them out. OP says he hears a noise and feels vibration when idling/revving. I think mount is possible, hopefully not engine issue.

Thank you everyone for your input. I’m having the truck looked at by a shop in the am to confirm my suspicion. However, after thinking about it more earlier today I did have an encounter on the highway at higher speeds that caused the truck to jolt very hard to the right. This was due to a road construction and a large grove in the road caught the right tire causing the truck to violently swing to the right.

The more I think about it the more I realize that this could have definitely caused the issue.

Other than at idle and revving I don’t feel the issue and while driving it doesn’t make any noise and that because it’s typically at a constant RPM when cruising. But coming to a stop not only changes RPMS but by applying the brakes moves the engine forward a little causing the noise and vibration. So far this is all just my theory on how it happened and what’s going on but hopefully it can be proved tomorrow morning. :fingers crossed:

 

[Lukkon]

In looking at the construction of the assembly, it's possible that one of the mount bolts could break, be loose, or the insulator could wear or break? I would inspect those mounts and insulators carefully to rule them out. OP says he hears a noise and feels vibration when idling/revving. I think mount is possible, hopefully not engine issue.

SOLVED IT!

So due to work I couldn’t make it to the shop today. However I decided to take a moment and look around the bottom of the truck. Had my brother help me in trying to pin point the vibration.

Took a closer look at the engine mounts by taking the wheel liner cover off by the strut tower. They actually didn’t move or clunk at all while trying the power brake test. This really got me thinking.

Took a very close look at the skid plates only to discover that the stock transfer case skid plate was still installed underneath the Shrockwork Skid Plates... had my brother turn the truck on while looking at the plates and guess what, they made contact almost every time.

Took the stock skid plate off and only left the shrockwork skid plates installed. No more vibrations at all!! Turns out when I revved the engine or put it into reverse for power braking the engine/transmission moved enough to make the skid plates come into contact.

Total cost of repair: $0

Thank you everyone for your inputs a lot of the early comments saying motor mounts were unlikely were spot on. However the symptoms were so close that it was very difficult to pin point initially.

(Photo of stock t-case skid that was removed with rub marks)

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