Mitsubishi Eclipse 3G Club banner

Prothane motor mount vibrations during drive

4K views 19 replies 6 participants last post by  Crazyguy03 
#1 ·
Hey all,
2000 Eclipse gt with manual at 145000

I put in 4 prothanes two days ago and right away noticed vibrations.
During idle and when driving. Idle I understand, but starting at 1700 rpm the car vibrates until I surpass 3200 rpm. It gets bad enough where the vibration is audible and my passenger and rear view mirror vibrate so much the image in them is discernable.

I've searched and all I could find is vibrations in the I4 or auto. But not in my config
Should note that my front and rear came as full rubber bushings, without predrilled holes apart from where the sleeve goes.
Should I try drilling them or is something else wrong?
Vibration minimal under hard acceleration.

Thanks in advance.
 
#4 ·
Passenger side was replaced when mounts were replaced. Had an issue with both a year ago and replaced both last august but the oem mounts I got had the sleeves slide out of the alum. housing.
And it's not as much a shaking as a vibration. Definetly engine based cause it's all with the rpm
 
#7 ·
The only thing that would need upkeep would be plugs and wires. I keep everything else such as suspension and driveline update and lubed. Could a bad plug cause this? Bought the car at 10200 and put 40000+ in 4 years. Not sure when plugs were. Last changed but it wasn't like this before the change.
 
#10 ·
It came with 4 sleeves to insert in each of the bushings. They seems to fit well on the bolts


The prince: it happens in all gears and nutural aka not moving just revving and when clutch is engaged. Definetly a mount or engine issue. Just don't know what cause no one else has had this issue.
 
#13 ·
Drilling no... That gives open room to rattle more ... It seems like there is a loose fit somewhere that will allow the engine to rattle. There is play in one of the mounts bare minimum and the rubber part of the mount isn't absorbing the sloppy movement .

How many inches of your dash has it cracked ??? For personal lol's
 
#15 ·
Did you have a vibration problem with the rear one bad? I think I may buy an oem rear mount and install that and see if it fixes.

Also, unrelated but might be related, I noticed that in 5th gear going about 35-40 when I step hard on the throttle, I get a sound from my engine bay. It's almost like a grinding but not gears. It just sound like akward meshing. I haven't searched for it here but I'm going to now. Just was writing and figured I'd ask but if there is a thread already I'll find it.
 
#16 ·
Not terribly, no. I had an auto so it definitely vibrated at idle, but after it started moving it went away immediately.

It's likely it's the front or rear, those are ones that transmit vibrations the most because the engine puts tension on them when accelerating.

Wheel bearings maybe? Or a bearing in the tranny going bad? Who knows. Does it happen only under load?
 
#19 ·
SOLVED

Hey all,
Just going to write here in case others find it useful.
I had to do a clutch replacement, and so three of the motor mounts were removed, and we had put 6 - 5/8'' holes into the rear mount.

I am not sure if it was that we took everything off and re torqued, or if it were the holes that helped, but regardless the vibration from the motor is gone.

So either take them off and re-torque, or go and drill a few holes in the rear mount.

Thanks!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top