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Vibrations after motor mount replacement

dbrannon79

dbrannon79

I'm getting there!
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Seguin, TX
Hey guys. I need some advice. About a week na half ago I finally replaced both motor mounts and the tans mount I bought from rockauto. I used the anchor brand rubber style mounts, same ones I could have gotten from the local auto parts but the cost was much less. Ever since I replaced them I have felt a constant vibration in the floorboard that I think is getting somewhat worse. It’s only at idle that I can feel it though, as soon as I press the gas pedal it goes away but it’s even more pronounced with the ac running I can get a foot massage sitting at a traffic light!

I have looked everything over and can’t see anything I did wrong and nothing seems to be touching the frame or body that I can see. I would hate to think the harmonic balancer is causing this. I did inspect it when I did the water pump and it looked good.


Today when I got home from work I popped the hood and watched it as it idled in the driveway. Placing my hand on the motor it seemed smooth but I can feel the vibration in my brush guard too!

Should I be worried or be checking anything??
 
I think the 4x4 mounts are different from the 2wd mounts...did you get the correct mounts? Are they polyurethane, I hear those can transmit vibration. Just something to consider. Good luck 👍
 
I looked up the mounts again to make sure I used the right ones. I’m not sure it’s what I’d call a rough idle but it’s like all the vibration is being transferred from the engine into the truck
Putting my hand on the engine when it’s running seems smooth and there’s no shaking!

Im curious if a pulley problem can be causing it other than the balancer. I suppose pulling the belt off will tell me that answer lol

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Something else just came to thought. Installing new mounts raised the engine a slight amount. Not sure just how much clearance there is around the top side of the bell housing but if I have bad cab mounts would there be a chance that the two can be touching?
 
Put floor jack under rear of the cab with some blocks. Push the cab up a lil and then feel brush guard...but I would think it wouldn't go away when accelerating and you'd more hear it if it was hitting the cab
 
Well, definitely let us know when you figure out what is causing the vibration. I tried replacing mounts when I installed my new AM General motor. I tried the polyurethane mounts but, I think I got the wrong ones as they would not fit in the clam shell. Wound up using the Anchor brand, worked perfectly.
 
Stoney said:
Put floor jack under rear of the cab with some blocks. Push the cab up a lil and then feel brush guard...but I would think it wouldn't go away when accelerating and you'd more hear it if it was hitting the cab
Click to expand...
Yeah, I think it would be a rubbing and a pounding if the enjun wuz again the cab.
I wiuld think a person might be able to get under the truck and feel 1/2 way around one side, in the firewall area, then do the same frum the other side and see that there is clearance all the way around.
 
MrMarty51 said:
@dbrannon79
Does the frequency of the vibration change when in neutral and rev the enjun at different speeds ?
Does it increase or go away ?
Click to expand...
it's a fast paced vibration. it does change in gear and when I turn the ac on it seems to get worse, but as soon as I accelerate anything over idle it goes away. best I can think of describing the vibration is like the vibrator in your phone but 200 times more lol. it's enough to put a tingling feeling in your feet and rattle all the change in the ash tray lol.

if I had to sit there idling for an extended period I know I wouldn't be able to stand it very long!
 
I will have a look at the cab and body mounts possibly this evening after work. I was trying to find a photo online of the mounts just to see if they might be reversible. I think their made like a two piece donut rubber and a center sleeve if I'm not mistaken
 
Hey I found something odd. I was looking at the motor mounts and they seem like there being pulled back a bit. I took some photos of them with my phone. Does this look normal?

the first two are of the drivers side, last two are the passenger side. It’s like there being pulled towards the back
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I did try something else too. I remembered reading somewhere about a similar issue that turned out to be the exhaust pipe causing vibrations. I slid under the truck and loosened the down pipe to intermediate pipe where the ball shaped joint is. Cranked her up and the vibration is much less than it was! Now I’m wondering if the flex pipe idea I had by cutting out a shot section of the down pipe and clamping some flex there will solve the problem.
 
I know on one of my trucks the down pipe was touching the cab after I put the ATT on it. I had to ream the slots out further on the down pipe elbow to change the angle.
 
Agreed Les, I can't remember if there is a left and right. By my memory they are the same, even then I marked which was which. I used the Poly insets and rebuilt the ones on the 1 ton.
 
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