Hello to all, I'm a new member and a relatively new Mitsubishi owner. Here's the issue. I have a 1998 Galant, AT, with the 2.4, I have a bad vibration through the whole car, it happens in park or in gear, and is especially noticeable at idle or low RPM's, it gets less noticeable one the motor warms up but is definitely still there. It was nice and quiet then all at once, the vibration started. At first I thought it sounded exhaust related but my down pipe, flex pipe, and cat are all new, and everything else seems to be fine. I had just bought the car and wasn't sure when the timing belt was replaced so I had that done, along with tensioners, and water pump. They told me the timing belt wasn't too bad but the balance belt was a little loose. Remember, the problem started BEFORE I had the timing belt done. So next I checked my motor/tranny mounts and found the front and back were both cracked, so I replaced all four, and no (very little) change. Then I found the crankshaft pulley/harmonic balancer to be wobbly and noticed the rubber inside was shot, so I replaced that. And still I have this "bad vibration" The mechanic who did my timing belt said he triple checked all of my marks before and after installation, but I can't stop thinking that maybe the balance shaft is off time. Maybe it could have jumped time before it was replaced, and he didn't notice? Or is this something else all together? I also replaced the air filter, spark plugs, and wires. The motor is strong, I have no loss of power or any other issues just this vibrating that's driving me nuts. Any input or suggestions would be greatly appreciated!!

 

You can try to have someone with a good obII scanner/diagnostic tool check all the vitals of your engine with it. They can check your timing with it, and all your sensors, maybe that will shed some light. I was thinking motor mounts at first but you've taken care of that already.
Good luck and post your results when you find the problem.

Wally
2007 Galant

 

Thanks Wallster. good idea about the diagnostic, I never thought of that since my check engine light is not on. Are you sure a diagnostic scanner can check timing? Oh yeah, I forgot to mention this: When I'm running my a/c or fan my RPM's drop VERY low at times (mostly at idle) and the vibration gets very bad then. When this happens, even at highway speeds, my headlights dim allot, for about a second or two.

 

Okay, well here is an update. I took my timing cover and belts off and found that my right balance shaft was off 180 degrees. The notches were lined up, but because of the 2 to1 reduction in the size of the pulleys, just having timing marks lined up isn't good enough. Instead of using the screwdriver through the plug hole procedure that's recommended in my service manual, I placed the mark on the balance shaft straight up (12 o'clock position) and let go. In the position the pulley was set, the timing mark on the pulley rotated clockwise (away from the mark on the block). So I spun the pulley one more rotation up to 12 o'clock, and viola, the mark rotated counter clockwise, and fell almost directly into time. So, I lined everything back up, assembled everything back together, fired her up and the vibration was completely gone. Here instead of dampening the motors vibration, the balance shaft was actually making the vibration worse!! But I have to tear it all back down again and re-time because something is out of whack. My RPM's are higher than they normally are at idle, and I'm getting a tapping noise from my valve cover area, along with hesitation, and a gas smell? I had a very difficult time finding the proper notches to line up my crankshaft pulley to time. There was a V notch cut into the plate behind the crankshaft pulley and a notch on the block around the 10 o'clock position, which I used, but it didn't look right, because the notch on the block didn't point directly to the the middle of the crankshaft. Also there's timing marks on the lower timing cover, which you would have to put on, then put on the harmonic balancer to even see if they line up, but there's 4 marks, above the three on the left it says BTDC, then on the notch on the right it has a T. So I didn't know which one to use or if it could even be done this way. My friend from work told me to just find TDC with the screwdriver in the #1 plug hole, then my crankshaft would be right on. I'd rather see the mark so I know it's right. Does anyone have a photo of where this mark is? That would be very helpful. Well anyway, I hope this helps someone with the same problem. It seems my balance shaft got out of time on it's own, I'm thinking either my tensioner came loose, or the belt stretched because this vibration started before the timing belt was replaced.

 

Manufacturers do at times, make corrections to their service manuals. I know Mitsu had several service manual updates for my 93 Talon. There may have been one that addressed the timing marks.