When I first start my GS4 up I sometimes hear a strange rattling from what sounds like below the dash or on the engine side of the firewall. It sounds almost like theres a mouse in my vents or something. I thought it might be something caught in the blower fan, but it happens with the heat/ac turned off. Also, the noise follows the RPM (more RPM, more rattle). It seems to fade when the car is warmed up. It's not that loud, so is tolerable, but is still something I'd like to fix.
Does anyone have any idea what this could be?

 

Hello,
I have heard of this kind of noise on cars that have had recent cooling system maintenance. Usually what I am talking about is the result of air in the system, working through the heater. There are a few places where the system can be bled, but the most common one besides the radiator, is the plug at the very top of the engine near the thermostat. This plug should only be opened when the engine is cold, and not running. Take the plug out, and carefully pour coolant/water into the radiator. When full, the coolant will come out of the plug hole without bubbles.

Then put the plug back in, start the car, and allow it to warm up completely. Turn on the heater, and set to 85.
I hope this helps. I couldn't think of anything else in that area.
GSEREP1

 

Isn't the thermostat in with the waterpump, buried under the exhaust manifold?

I have a rattle, so far only finding this post...any followups, confirmation, other info?

Thanks

 

Kinda +1 on what 2kGS400 said. When the engine is completely cold and I do mean completely cold, take off the radiator cap. Start the engine and turn on the heater. Then add water/coolant while the engine is running. The air bubbles will work their way out.

 

Thanks! K. Sounds worth a try.

The sound I'm hearing is more ...."metallic". Like a loose piece of sheet metal vibrating against something.

I suppose it could be a number of things, but is that the type of sound these air bubbles would make?

 

On the topic, I could add that I have been worried since buying this car a month ago (first Lexus for me) that have smelled anti-freeze....seen some leak out onto the lower engine cover. And when I took to have inspected they spotted these drops coming from a bolt near the oil filter (pic they took will be below).

Its been overwhelming to take in the amount of info I have about this car, fast as I can...but somewhere I recall something about some coolant drain plugs on the lower part of the block?

Supposedly the timing belt change was done a year ago...don't know the skill of who did it. I noticed there's an overflow tube top of the radiator,(overfilled?) and has green coolant in it - is that bad? Guess I should get it pressure checked - just don't want someone to see dollar signs, and have enough other concerns to address if this isn't necessarily highest priority.

Whole things been kind of maddening to take in - actually it took me a bit to realize all the LS and SC info that pulls here would be totally diff to GS...wish there was a way to restrict search results to the forum you want.. And don't know if enough people see your question if you respectfully try to put within existing older threads on same topic

Anyway, If anyone has any experience or wisdom to share here I'm most grateful.