Vibrations

[Jon Blaze]

I own 2 trailblazers 06 4/4 4.2 one has 76000 miles on the other has 59000 miles.
The one with 76000 miles on has a vibration in park-neutral-drive rpms do not go erratic. I put in reverse and no vibration. I had someone inside and put it in gear and stab the throttle on both of them engines move the same way. I did change plugs and all 6 coil packs ac delco also cleaned Tb pulled both fuses before I started any work.
Thank you for all your help

 

[Blckshdw]

How do your motor mounts look?

 

[Capote]

Most likely the motor mounts as stated above

 

[Jon Blaze]

They move the same as the other trailblazer as from what i can see. Is there away to check them besides having someone in the driver seat stabing the gas?

 

[Jon Blaze]

Ok just removed passenger side mount and no cracks or melted rubber. I did shake it and it sound like there is a rock inside it. I ordered new mounts and i will check them when they come in.

 

[webdawg]

Ok just removed passenger side mount and no cracks or melted rubber. I did shake it and it sound like there is a rock inside it. I ordered new mounts and i will check them when they come in.

If I remember mine did not 'look' (I also tried to feel but they are such strong mounts) bad but when I put the new ones one, what a difference. They are hydraulically filled if I remember and I think that makes all the difference when replacing. The drivers side kinda sucks to do. I ended up drilling a hole in my PCM/electrical harness bracket to get to the top of it(the fuel lines are right there on mine)...you have to raise the engine but the front fan hits the shrowd so you have to loosen the fan shrowd. Still, I barley had enough space to get the old out and new in on the drivers side. The engine/intake started hitting the firewall, the intake manifold was under stress...I was very careful at that point and had JUST enough space to make it work. The warning is to not crank on the engine and damage the fan/intake manifold.

You also have to deal with hugging the strut and spring on the front to loosen the lower motor mount bracket...the service manual says to take it off, but I just worked around it and I could do what I had to do.

 

[webdawg]

They move the same as the other trailblazer as from what i can see. Is there away to check them besides having someone in the driver seat stabing the gas?

I forgot to mention but there is a transmission mount under the car by the end of the converter...it is usually under a lot less stress then the motor mounts. My car is at 170k and it seemed just fine (I do not know if someone ever replaced it). When I did replace mine (I kept the old OEM, it was fine) I was under the car doing exhaust work and both of the bolts that hold it on were in stripped out holes. I think the person who replaced the tranny did that part. (or possibly someone did replace it?)

If I remember correctly you will see movement while looking under the car and have someone going from reverse to drive. Do not get ran over, really...I never got in front of any tires.

After taking the tranny mount out, it looks to be built of very strong rubber only and I think if you were able to get under the car and look at it, if the rubber is intact and you see very little movement, it is most likely fine.

 

[Jon Blaze]

I check the trans mount it look good very little to no movement. I was out there for 4 hours messing around with the mount on the passenger side. Now i know you dont need to take the mount off the frame. Pull 3 of the 4 bolts that hold the mount to the block and it moves the mount right out of the way and pull the rubber out. No trim of the screw thread.

 

[webdawg]

I check the trans mount it look good very little to no movement. I was out there for 4 hours messing around with the mount on the passenger side. Now i know you dont need to take the mount off the frame. Pull 3 of the 4 bolts that hold the mount to the block and it moves the mount right out of the way and pull the rubber out. No trim of the screw thread.

Did you do the drivers that way? Just removal from the block?

 

[Jon Blaze]

Yes then go under to pull bolt from bottom of the mount then go thru the wheel well close to the cab at the ground mount. Use a 18 mm wrench take off top nut on mount then pull mount out thru top between master cylinder and intake After you remove the vac hose to brake booster. Slip mount back in thru the same hole. Also you still need to jack engine up just not as far as the other way of changing it.