still runs good right? just overheats at idle and if you give it gas while driving it will go back down the temp gauge correct?

 

Water has to be going somewhere. Its a closed system by design. Just this past weekend I had helped replace those two short tubes that are hidden behind the engine bay on a friends ls400. PITA. One was going from the throttle body down behind the engine near the firewall, then the other close to the egr tube that runs behind the intake.

 

Thermostat FAILED by the looks of it.

 

put a glove on (weird way to start off a sentence) and squeeze hose going from engine to radiator with the car ON. if u can squeeze it, its definetely ur thermostat. and yay thats like 12 dollars. if not be gangster and just throw that crap away and reconnect hose

 

He said t-stat is good. If the coolant can be seen flowing when the (17mm) bolt is removed from above the T-stat housing, then it's not stuck closed. When my heater core was shot and leaking there was never any coolant inside the cabin, it all stayed in the heating ducts. If that happens, you don't notice the leak. If your windows are fogging up a little, (especially the 2 front doors) then that could be where your leak is. I had the same symptoms as you when mine went, no heat, low coolant, gauge fluctuating. (air in the system)

 

i may be wrong on this but the thermostat doesnt have to be stuck closed for it to be bad... it can still be malfunctioning, still allowing water to pass but just not enough. i would remove it all together just to see wat happens. if the car doesnt over heat anymore then just buy a new one. if it does just put the old one back in. u know its worth a try. sometimes cars are weird and frustrating i would try anything just to eliminate all suspicions . IMO

 

True but, he's losing coolant somewhere, so the T-stat is not that problem. The car is overheating b/c there isn't enough coolant. But I do understand your thinking and the T-stat is a cheap enough part to just throw at it anyway if it hasn't been changed recently.

 

yes sir... i have a question here for everybody... if not enough water is getting to the engine, because the engine is hot, wouldnt it just burn the coolant/water!?!?!? is ur car blowing out white smoak atleast even a little?

if this is a stupid question forgive me but im just trying to be bill nye the science guy... lol

 

No it wouldn't just "burn the coolant", that's the purpose of coolant. If it was straight water it might just evaperate but it wouldn't burn through the exhaust. (Unless ya have a blown head gasket) If there is white smoke from the exhaust it could point toward a blown head gasket or it could be the, very common, bad ACV valve on the PS pump blowing fluid into the intake.
Bill Nye needs to experiment some more. My kids used to watch, and make fun of, him.

 

lol it was just a question man. i meant to use that word (evaporate)... lol... and that guy is my hero lmao

 

Thank you to all. I believe DeanShark is on the right track. White smoke rises from the resevior only when I mix water with coolant. Temp guage replaced 3 months ago.