Best time to check coolant level.. HOt/COld?

[roperteacher]

I posted the other day that I was losing a little bit of coolant thru the overflow tube on the plastic bottle. As advised I placed a clamp on the return hose at the Radiator and Plastic bottle. Never had a single drop from those locations, only out the top, but figured it was a good idea.



Well, pulled the horse trailer today in 90 + degree heat with AC blasting and NOT A DROP of collant came out the top!!! Have no idea why it worked.





My question, when the engine is Hot and up to operating temp, the coolant is Exactly on the BLue line marked on the reservoir. When it is cold after sitting overnight it lowers to maybe 1/4" below that blue line...





Which is the most accurate reading hot or cold? THanks!

 

[DPKetchum]

Eaither. Its between add and ok isn't it?

 

[roperteacher]

Yep, there is a "Add" mark on the plastic bottle and a "Full" mark. There is also a man made blue hatch mark that had been drawn on the side of the plastic bottle from the factory. I would say the blue line is about 1" from the FULL mark at the top. When cold the bottle level reads just below the blue mark by a tad and Well ABOVE the "Add" mark... .

 

[rbattelle]

That's why there are 2 lines: max and min. Coolant will naturally move between those two marks as environmental conditions change and the system equalizes over time. Perfectly normal to notice some movement.

As long as it remains between the lines, leave it alone.

Ryan