I am completely new to this board and I have a question I hope someone can shed some light on..
I have a 2001 SE with about 78,000 miles on it. I started to notice a bad surging when letting off of the gas or when the transmission shifted. I also noticed a pretty bad vibration at idle. I found a bad front tranny mount. ( the oil filled one totally torn apart.) I replaced that one with a factory one and it was much better as far as the surging. But the vibration is still there. I have checked all of the motor mounts plus replaced the rear tranny mount as well. All of this still leaves me with a vibration. Im not sure how smooth these engines are supposed to be. but if I put my hand on it while its running. It seems to be rough running.
The strange thing is the vibration completely disappears once i get going over 5 miles per hour. Im lost here. If anyone could give me some ideas on where to look... I'd really appreciatle it..
I'm going to go out on a limb and say it'* the car, not the engine. my car, same chassis, also has a vibration at idle. our 95, 92, Bonnevilles did not have a vibration at idle, nor did my 97 supercharged 3800 Riviera. I'm not sure why the 2000+ models vibrate like that though.
As for excessive vibration, do you maybe have a vacuum leak somewhere? How old is the PCV valve?
I will indeed take a closer look at the possibility of the vaccum leak. The engine was torqueing so bad when the mount was bad that the snorkel that attaches to the aircleaner actually came off.. So, its very possible that a line is off somewhere too. I have no idea how old the pvc valve is.. but i will replace it anyway..
The only reason this is bothering me so much is I didint notice this vibration before, just the last week or so.
thanks again for the fast replies. it puts my mind at ease know that this is a common thing and probably normal for this car.
I forgot to add one thing. The vibration is there slightly when if park. If I put into reverse, it gets worse. Drive is also worse, but not as bad as reverse. I thought tranny at first, but the tranny works great. It shifts fine and doest seem to have any of the other problems that I have read about. I have looked at the harmonic dampner.. but is there a way to tell if its bad? From the outside. it looks fine. I thought about running a paintline over the entire outside to see if it spins.
I'll see what i can do about posting a video.. I may take it to the dealer like you suggested . I also have to get the keyless entry programmed.. so maybe I'll do it then.
Did you have the bad motor mount replaced? And if so was it replaced with OEM or after market unit. The reason I ask is that most parts stores (NAPA, etc.) have OEM style and usually stock the solid replacement instead of the liquid filled one that came on the car. I'm not 100% sure yours came with liquid filled or not, but the cars that do sometimes it makes a noticable difference and sometimes it doesn't. Just something else to think about. Also depending on which mount the engine torques against in reverse would also lead me to look at the mounts. GM-Maine
The transmission mount is a factory oil filled replacement. I got it at the dealership and it is a GM. The rear transmission mount is also a factory replacement, Although I dont think that one was bad. the front one was almost in half it was ripped so bad. there are 2 more mounts that i have not replaced. These are on the drivers and passenger side. I believe these are called the motor mounts. they look ok and i have pulled on of them off the car and it seems to be fine. There are some slight dry rot cracks if you pull on the bolt, but its fairly tight.
These are the things that I have recently replaced. Although all of these items are after the vibration has become noticable.
sparkplugs and wires
coolant temp sensor
gas evap sensor. (the one on the engine)
front and rear transmission mounts.
Im not sure about how to post a video. Also, Im not even sure if the vibration would show up. Its more of a feeling than a noise. If you have any ideas. please let me know.
Again.. thanks everyone for your input.. If I find out anything .. ill be sure to post it.