NicoN

Hey guys I need help with my 2009 LS460. It has 95k miles as of today. Lately when taking off from a stop I hear rattling under the car. I can only hear it with the windows down and if I’m next to another car or building. Today I dropped the skid plate and checked all the heat shields underneath. I’ve seen one post by someone on here that had the same exact sound and how I can replicate it with the car in drive, giving gas while I have a foot on the brake. But OP never posted fix. In idle if I rev no noise. Once I reach around 20-25mph there’s no noise at all. Car shifts and drives perfectly normal. Any one ever have this issue ?

Tdes395

Wrong octane gas

NicoN

I filled my car at a different station and same thing, I’ve always filled 91 for the last three years I’ve owned, made sure oil was correct and level 5w-20, and Lexus changed the trans fluid twice and third time changed filter. I just don’t understand why I can’t replicate it in park and with revs. The trans fluid was changed 2 years ago 13k miles ago.

dan25man

Bro why do people say it's a gas issue on every post now.... knock is corrected automatically by the 4-knock sensors and ECU and a hard misfire would throw an engine code...

Hard to know exactly, but I have a similar transient warm up rattle. From a cold start from the 3 min till 6 min mark at idle there's a oscillating noise coming from the drivers side valvetrain, towards the front of the engine.

I'm currently replacing the valve cover gaskets and the timing chain, and cam lobes look fine. My running theory is a known issues on these 4.6L and the 5.7L engine where the drivers side tensioner takes a while to build pressure. So your chain is a little slack and clanging against the chain guides. There's a TSB EG-0031L-0516 documenting the issue.

See:
At the 16 min mark he discusses the timing chain issue with the 5.7L. It's the same design on our 4.6L. I've had the noise for like 20k miles so seemingly not going to destroy my engine. But one day I do plan on pulling the front case and replacing the bad tensioner.

If you are concerned about it and want to get it fixed find a good indy shop in your area that works on Toyota/Lexus products. It's a big job because they have to pull the valvecovers, and front case, so there's lots of things in the way. Probably a $1,500-2,000+ job.

NicoN

I see what you are saying, if it is a tensioner issue why doesn’t it rattle in park with revs? It would be same oil pressure at that rpm in drive or not. It’s confusing. During cold start there is no knock or rattle or anything. Only happens under load. As I get to 15mph the noise is non existent. Car has been serviced religiously. I changed all the fluids at Lexus even two transmissiondrain and fills and filter change. I’ve heard the chains slap on this car in videos it’s way louder.