Hello.

I could use some help with a basic question ie. what is the correct coolant level in the reservoir when engine/coolant is cold?

On my reservoir I have these two lines and if my cold level is on the lower one it tends to push just bit of coolant out from sensor on top when coolant expands.



Of course I could/will just lower the level a bit but what is the "official" cold level supposed to be?

 

If I'm not mistaken that tank gets pressurised when the engine comes up operating temperature. If its leaking around the sensor you may have a bad o ring.

 

We changed the O-ring already as the old one was hard. It's seeping through the new one too but not so much.

Is the reservoir supposed to be full of coolant when the engine is at operating temperature or say half an inch below cover edge?

 

I think mine only comes up an inch or so. I'll check it later and get back to ya.

 

The lower line is cold so that is where it is supposed to be for nominal operating conditions. If it is still leaking, may also want to change the reservoir cap. This is responsible for maintaining proper pressure at operating temps.

 

Forgot to mention that cap is also new OEM part. Thermostat and waterpump were changed too when we did the timing kit. Temperature gauge needle stays rock solid at half way.

 

My 98 Celsior doesn't show a big level change. When cold, the level is the center between the middle of those 2 lines and when fully warmed up, it goes up a bit higher than the top line. So the level change is less than 1cm. I use the Toyota genuine coolant and the density is 40%. (I mean water 60%.)

Come to think of it, the expansion rate by heat of the liquid (40% density) is only 0.066% at 80 degrees C according to the data sheet and also the liquid is pressurized, the level change should be just a little bit. It doesn't expand as the ATF does.

Let me calculate how much the capacity increases when the temperature changes from 20 degrees C to 80 degrees C.
11L X 0.066% X 100 X (80-20)=0.44L

There also exists the pressure and the capacity change should be less than 0.44L.

 

My 92 leaked some too after other fixes failed. Bought a whole new tank. So far no leaks. Think i read somewhere the tanks had a design change that helped them not fail. But i think after 20 years it was time to fail.

BTW i keep mine closer to the top line.