Coolant level when hot
 

A week ago, I went for a drive of about 20 miles, mostly highway. The ambient temperature was in the 60s. When I got home, I wanted to check under the hood. I happened to notice that the coolant expansion tank (or degas bottle, as Ford calls it) was almost completely full.

Today I went for a similar drive. The tank, right after I shut off the engine, was filled to a hair over the top fill cold mark. This is where I remember it being in the past, except for last week.

When cold, the tank is filled midway between the top and bottom cold fill marks. The car has 13,500 miles on it and is about 4 1/2 years old. It has the original factory coolant.

The temperature gauge stayed midway on the scale, but I think the needle is designed not to go past midway until there is a serious problem. I don't think it shows relatively minor fluctuations in temperature.

Do you think this is a problem about to happen, or am I probably concerned about nothing?

Thanks.

if its not over heating, the coolant level isnt low, and the temp guage isnt bugging out your good to go.

What's the issue? Coolant will expand when hot and contract when cool. The expansion tank is there for just that reason; to catch the overflow as the engine gets hot and to allow the block to pull it back in when it cools. The level can vary from drive to drive. You're describing a normal condition, IMO.

Yep. sounds completely normal to me as well. If you are attempting to take the cap off (hopefully using the "six-finger method" for safety) and feel a "bubbling" feeling, then you might have a problem. I had that happen with a Cadillac before at work. After like 5 minutes of tiny 1/16th turns, I called my boss over to check it out. Within five seconds he confirmed that the coolant was actually boiling and that we weren't able to check it.

Also, not to be "that guy," but I just recalled that coolant flushes are due every 5 years or 100.000 miles on our cars as the additives start to break down and corrode the radiator. Just a friendly reminder if you are still extremely worried about it. :)

If you do decide to change it, use Zerex-G05....

http://www.valvoline.com/products/br.../antifreeze/42