Bad engine noise

3A-C Power · Post by **3A-C Power** » Sun Oct 31, 2004 1:04 pm

I am getting a loud sort of rattling noise from my engine from about 1500 to 2000 rpm and I can't figure out what it is. It doesn't sound like clicking valves or a rod knock or anything internal, but rather like something is loose and is resonating with the vibration of the engine when the frequency is right. I have tried to locate the noise under the hood with the engine running, but can't seem to find where it's coming from. It's bothering me more now that my transmission is fixed and you can hear the engine so much more. Any ideas?

russkiypenguin1 · Post by **russkiypenguin1** » Sun Oct 31, 2004 1:18 pm

I know my starter broke free one time and made a pretty bad racket...but it also began grinding when it started...

GTSSportCoupe · Post by **GTSSportCoupe** » Sun Oct 31, 2004 2:10 pm

An exhaust piece? A bearing in your alternator? Some other bearing (waterpump, power steering, belt tensioner)? A loose accessory bracket? Engine mounts?

takza · Post by **takza** » Sun Oct 31, 2004 3:10 pm

Maybe the heat shields on the exhaust or engine? Try taking a wooden hammer handle and after getting the engine at the speed where you have the noise...try to stop it with the handle...avoid all moving parts of course.

3A-C Power · Post by **3A-C Power** » Sun Oct 31, 2004 6:09 pm

My friend had this same problem - only when I looked at her car I found the cause right away. It was the water pump. My noise sounds like it's coming from the rear of the engine, right around the firewall. I have checked that valve that goes from the exhaust manifold to the air filter, but it is okay. Nothing in the exhaust seems to be bad, and I just changed the manifold gasket. Also, the noise seems alot worse when I'm inside the car than when I'm looking under the hood trying to fix it. But I don't think it's coming from inside.

warbstrd · Post by **warbstrd** » Sun Oct 31, 2004 10:02 pm

that thin metal heat shield that goes down the exhaust in the engine bay? mine was loose and made a very light hardly noticeable clanking noise, drove me nuts till it got a new exhaust gasket (it was leaking) when i tightened everything back down no more clanking noise so i just figured it was that heat shield.

3A-C Power · Post by **3A-C Power** » Mon Nov 01, 2004 1:51 pm

I found out last night that there was only one bolt holding the alternator bracket on, out of four bolts. I was able to add another one and will add the other two soon. The noise is different but not gone. I checked the heat shield but that's not it.

GTSSportCoupe · Post by **GTSSportCoupe** » Mon Nov 01, 2004 3:34 pm

I had the same problem with the alternator on my AE86 one time. Made strange noises as you described, and the bolts fell out. After lots of messing around, I figured out that the bearings in the alternator were messed and creating a vibration that knocked the bolts out.

3A-C Power · Post by **3A-C Power** » Wed Nov 03, 2004 4:25 pm

The noise is fixed. It was something to do with the alternator, or the bracket. When I put all 4 bolts in the bracket, the noise went away. Nothing seemed wrong with the alternator though.