Engine noise?

[jduncan]

First post, been reading for while. I got a quick question. I have a 89 lxi 5spd with about 215k on it and once in a while on startups or when cold i get a hard vibration. seems to be coming from the engine but i cant narrow it down. its more noticable from inside the car but when i get out and lift the hood, i can barely hear it. it also occasionaly happens when im pressing the brake pedal down, even when warm, and seems to disipate (sp?) when i take my foot off or press the accelerator. any suggestions or ideas?

[2oodoor]

It would help you to narrow down the description. You say hard vibration but then you say you hear it when.. so vibrations you feel, and they resonate off of objects to make sound.
At first I think brake booster which takes vacuum and thus could affect engine idle speed. Is it when you are braking or just sitting still on the brakes? do you feel it in the steering wheel, seat, floorboard , brake pedal or all of the above?
Try and imagine the weight or possible force energy of the vibration and compare it to parts under the hood that could produce that size of force energy. Vague statement < I know

[jduncan]

it happenes when im at a stand still. sometimes at start up or when im standing still on the brakes. it feels like its coming from the driver side defiently , i usually feel it through the floorboard. it feels like a pretty big vibration, but im not sure where its coming from.

[Dr_Snooz]

Given the miles on your car, there's a lot that can go wrong. I'd say start by checking your motor mounts. If you could you describe when this began and how, that would be helpful.

[jduncan]

It happened again this morning. Same hard vibration. just started the car and it started going, i felt it though the floor and also through the steering wheel. my car has got 215xxxkms on it. it began maybe a couple months ago. it also happens when im at a red light and pressing the brakes. stops when i take my foot off the brake and hit the accelerater a little.any ideas? my front brakes are very, very low, would that have anything to do with it if it is the brake booster?

[2oodoor]

could be just the check valve for the booster
the vibration as you describe it sounds like motor mounts or exhaust hangars

[jduncan]

i think you may be right with the mounts. i work for a parts place and a tech just came in and he said it is most likely that as well. i will get it checked out as soon as i get a chance.

[Oldblueaccord]

Also what is your RPMS at idle? They really should not go below 800 rpm. If its idling at zero,on the tach, that would be the vibration and like said must be caused by some kinda of vacuum leak with the brakes.



wp

[jduncan]

Looks like it definetly was the rear mount. had it changed yesterday, car is running smooth and sounds alot better, thanks

[Chkn Sanwch]

Yea man, I think it's a motor mount. Ive got an 88 LX and she's got some rough shaking to her every once in awhile. I thought it was a motor mount, but I recently put seafoam in my tank, and she's running ALOT smoother. Depending on where your idle is sitting may be indicative of whats causing the vibration.

Also, keep in mind that you will always have some sort of vibration or light shaking due to the fact its a four cylinder, especially that old of one. A V6 or V8 will offset most of its vibration with the opposite cylinders; ie--the cylinders on the left will transfer their movement to the cylinders on the right. Where as a I4 only has its motion going up and down. Just some food for thought, thats all.

[Chkn Sanwch]

Oh wow...I didnt even see your post before mine.

My bad, lol.