Hello, my sister's 2006 Acura TL is having a common overheating problem. Seems that after I fill up the radiator it's fine for a few days and then resumes overheating or visible leak. There is no white smoke in exhaust or milky oil. I have replaced the fan and its relays as well as the thermostat. The reservoir is full of coolant but I have never seen the car draw from the tank. Any tips would be greatly appreciated! Thank you

 

You might have a stuck shut thermostat. Only way to find out is the drain the coolant and test or replace the thermostat.

 

How would I test? I just replaced the thermostat 3 days ago so I am not really sure. Is there anything else you might think?

 

Yikes

 

So you need to refill the coolant or car overheats?

If you want to test your thermostat:

 

You need to take it back out to test it like in the above video.

What thermostat did you use and did you bleed the system properly?

 

I had the same issue, it ended up being a bad Heater Control Valve.

 

Bad heater control valve? You mean that it was leaking?

Because if it was stuck then there's no way it should cause overheating condition.

 

There's a coolant bleed nipple on the block. Crack it and see if any air comes out. Most likely you have some air in thr line. Also if the pump is doing it's job, you should see a good stream out of it.

 

Yes, the Heater Control Valve was leaking.

 

You wouldn't crack the block drain to let air out, even while the engine is running. Because that drain screw is by the rear of the block, having coolant squirt in your face lying down there watching it while you crack it open is silly. Just leave the radiator cap open and run the engine until the fans come on to bleed air, with heat turned to max to open the heater core.

I don't see how a bad heater control valve would cause engine to overheat, it just controls coolant flow to the heater core. The heat flowing into the cabin would be broken