Hello, have a 1999 Civic Si D15B Vtec swap. i just had the head gasket, timing belt, water pump and every seal sealed in the engine. i noticed when im accelerating slowly or down shifting i hear a rattleing sound kind of like a bearing spinning around, Then when im in neutral it will rattle a bit then stop.. Anybody know what this is? Gets pretty annoying. it's a very fast paced rattle sound.

 

Check the exhaust heat shields.

 

i removed the heat shield covering the headers because it was rotten. my headers are rotten too. but it dont think its the exhaust

 

There are other exhaust heat shields. Pretty easy to check them.

 

okay , i'll check it tomorrow. Thanks

 

Fixed.

 

I had a similar problem after my b16a swap. My rattle was coming from around the mid pipe heat shield.

 

Nah, it's the input shaft bearing in the tranny rattling.

 

How do you know?