Hi Scotty,
Is it normal that the coolant level in the reservoir drop? If it's normal, what is the accepted amount of dropping?
No overheating, no leaking, new radiator cap and thermostat, new coolant. Fan work normal. No gasket issue.
Elantra 2015
I had the same issue where would drop maybe a pint a week. I gave it some more time and found that it was leaking around the water pump where it bolted to the engine block.
@tlc1975 thanks for reply
It's not normal to have any noticeable amount of coolant drop. (Aside from the difference you'll get between hot and cold coolant.) It's either leaking or burning.
@chucktobias thanks
The cooling system is a closed system. As the coolant heats up, it should expand, not contract. Coolant expands when heated, and the coolant is also under around 15 PSI of pressure when at operating temperature. That's why it says on the radiator cap if the engine has been running up to operating temperature, you must leave the cap in place until it cools down. If you take off the cap right after you shut the engine off, the liquid will flash turn to steam, scalding you.
You have a leak somewhere. Get a coolant pressure gauge from AutoZone. They're free to rent. Read the instructions, and pump up the cooling system. It should stay sealed. Give it 15-20 min. If it leaks, you'll notice coolant on the ground.
If there's no change when you use the pressure gauge, your radiator cap is worn out.
@justin-shepherd thank you very much for valuable information