expansion tank fluid level

[grasshopper]

Hi everyone. Can anyone tell me what the proper fluid level is supposed to be in the expansion tank ? There is a thingy in there that sticks up and has breathing holes in it. Is fluid level supposed to be covering that or below it ? Thanks.

[18Fiatsandcounting]

I don't know if there's a specification for this, but I try to keep the level in the expansion tank about half way full. There is a "Min" mark on both my expansion tanks, about 1.5" from the bottom, roughly 20% full. There is no "Max" mark.

-Bryan

[DieselSpider]

Hi everyone. Can anyone tell me what the proper fluid level is supposed to be in the expansion tank ? There is a thingy in there that sticks up and has breathing holes in it. Is fluid level supposed to be covering that or below it ? Thanks.

Well below the top of the tube which is the overflow tube. If the level of coolant rises above the holes near the top of the tube it will just pour out the overflow drain hose. Level should be about halfway between the top of the tube and the Min mark.

[grasshopper]

So fluid should be below the breathing holes ?

[spider2081]

So fluid should be below the breathing holes ?

I don't think so. I think one of the functions of the expansion tank is to keep the cooling system isolated from outside air. I have always filled my reservoir so the top of tube with the vent holes is covered. This way as engine heats up coolant expansion will raise the level in the tank. as the engine cools it can draw coolant back into the engine. My thought is if the vent holes are not always covered with coolant as the engine cools it will draw air into the system.
I think the Haynes Manual stated fill to 2 3/8 to 2 3/4 inch above the min mark on the tank. This is about the top of tube inside the reservoir tank. Somewhere else I read fill cold until 2/3 of the reservoir has fluid.

[grasshopper]

Thank you. That makes sense. I will make sure.