diykid

Hello boblexus430,

I have the exactly same problem on my 2003 LS430. There was a leak on the passenger side behide the O2 sensor just inside the heat shield. I took it to local repair shop. They cut out the leaking section and welded a new pipe for the area. It cost only $80. But the heat shield was taking off. Anyway, it's a quick fix for the leaking and noise.

Recommendation to prevent from happening again.

I did buy a can of exhaust manifold paint and painted the flanges and new Y pipes. From what I could tell after removing the heat shields, the clamps heat shields and insulation caused the pipe to fail. If you could take the shields off and paint the Y pipe with exhaust manifold paint I think this would prevent this problem from happening. Also recommend replacing 4 bolts and gaskets after cleaning up the flanges.

1) the clamps rusted

2) the heat shields started to rust

3) the insulation trapped water and caused the Y pipe and everything else to rust.