I have a 98 GS300 with 122,000 kms and it makes this tin can rattle noise when accelarating. It usually happens around 1100 to 1200 rpm when the engine is warmed up. Last week went to a lexus dealer and they could not diagnose it properly and told me to tie down the heat shields. Brought home and now I have 5 or 6 tie downs on the heat sheild and the noise is still there.

It seems to be coming from the manifold area. Could it be a cracked manifold? This noise only happens when the car is hot so I suspect the expansion causes it to rattle.

Any help?

p.s i have searched the forum.

 

Maybe a crack in the heat shield. It could be expanding when warm and then rattling.

 

check your fans/fan clutches for any front to back play. they could be moving and hitting the shroud.

 

Are you positive it's not the catalytic converter covers?

 

The sound is coming from heat sheild closest to the manifold. The catalytic converter is futher away and even with a stethoscope by Lexus technician they point to the area closer to the manifold.

 

I see, did they put it on lift running?

 

The noise only comes when it is on load, so no they had to put it in drive with the breaks on and then hear the noise.

Next thing I will do is go to another Lexus dealer and let then find out.

 

Good luck, try asking member JPI, he might be able to help.