I just replaced the water pump on my civic. Its a stock 91 dx. I also replaced all the belts while I had the car apart. I noticed now that when I hold the brake pedal down or turn on the a/c the car vibrates irregularly. It's noticeable especially when I'm at the stop light with the brake pedal held down. The second I let go of the brakes the vibration stops. I was thinking if it had something to do with the alternator? Could it be that the tension on the belt needs to be adjusted?? Could that have something to do with it?? I marked where the alternator belt was at before I replaced it, and I tightened it down in the same place. Should I adjust it so the belt is tighter or let off some of the tension?? Any ideas?? Thanks.

 

I could be your timing belt tension peej.

It wouldnt hurt to try readjusting the alt belt first.

You could also remove the AC belt to see if the brake behavior still happens without it.

Does turning on your lights affect idle?

Do your brakes feel any different when you are driving?

 

My brakes don't feel different. Same as before the belts were replaced. I have notice the car vibrates when the lights are turned on. Could it be that my alternator is going bad?? If I adjust the tension on the alternator belt should I go tighter or loose to get rid of the vibration??

 

Just go ahead and adjust the tension on the alternator belt. Have you tried turning on your lights and all of your accessories? Does it do the same as stepping on the brakes? If not, could be a problem with the brake booster or the corresponding vacuum lines.

 

I'm gonna tighten the belt later tonight. Hopefully it will get rid of the vibration. It it turns out to be my brake booster or the vacuum hoses coming off of it, how hard is it to replace those?? If i just change the vacuum hoses will I have to bleed the brakes? How about the booster and the hoses? Thanks for the help.

 

If you don't take any of the brake lines off, you shouldn't have to bleed. ...but I don't know how much give you'll have in the lines if you have to replace the booster.

 

Alright..Thanks for the help everyone.

 

Keep us informed on what it turns out to be.

 

Looks like it was a combination of things. I tightened up the alternator belt and that reduced the vibration allot. I also adjust the idle speed and its gone now. I guess the idle was too low which was affecting the vacuum. Thanks for the help.