Coolant level drop slightly in cold weather?

I'm fairly certain that the slight drop (maybe 1/8 inch) in my reservoir as the temperatures have dropped is normal, but figured I'd ask for others experiences. I don't remember any change in the level for the first six months I owned the truck (January to July, but maybe wasn't paying attention).
Thanks, I'm just a little nervous since the belt tensioner failure incident over the summer, when the temperature flew up and spewed out several ounces of coolant.

 

1/8” ?

I’d say it’s normal.
Coolant is like any other substance, it expands and contracts with temperature.

I’d start worrying if it went down 1/4 of a tank. But not 1/8”

 

Thanks. When I topped off what had spewed out back in July (can't recall, maybe 12 to 16 oz), it was 90 degrees outside.
I checked it three months later, in October when it was maybe 55-60 degrees out, the level had dropped 1/4 inch, I had to add almost 12 oz to get back to the full line. Since then, the outside temps have dropped more and the level has dropped very slightly (1/8 inch).
I suspect you are right, normal due to temperature. Thanks for the reply!

 

When you say spewed out.
Did you add to the radiator at that time?

If so, it’s completely normal.
It takes some time for all the are air to purge from the system.
That’s one of the reasons (but not the only) the low and full mark is pretty far apart.

 

No, only added to the reservoir.

 

The coolant level in the tank changes with altitude.

 

I'd say it is normal. Coolant expands a lot when it warms up. During the hot summer months, mine is at the exact "full" line on the reservoir when the engine is fully warmed up/hot. Cold engine: it sits about halfway between the Full and Low lines. Check the level when the engine is cold too. During the winter the coolant level reaches to about 1/8" or so below the full line when fully warmed up. If it's real cold out, the level will drop to just above the "low" line after sitting overnight. (about 1/8th of an inch) I do not top it off in the winter as it has never reached the "low" line when the engine is cold.

 

Thanks for the info, much appreciated!

 

Not a problem. Hope it was helpful. Verify the reservoir level is above the "low" line when the engine is cold, ideally after sitting overnight, and close to or at the "full" line when it's hot and running. About half-way (cold: engine off) between the two seems to be the sweet spot on my truck when the engine is cold, regardless of the seasons.

 

I have mine filled to the FULL mark cold, maybe too high? If so, maybe it's overflowing slightly.

 

Might be, but I wouldn't stress over it. The manual says the coolant level is satisfactory if the reservoir level is between the "full" and the low" lines on the reservoir. Check it full-hot after a drive with the engine running. The function of the reservoir under normal operation is to hold coolant as it expands in the cooling system and to prevent the system/engine from drawing in air as it cools and contracts. (sealed system) You always want to see some coolant in that bottle when the engine is completely cold indicating that no air could be drawn into the engine.

 

I live in Minnesota and mine varies about a half-inch between a cold start in the morning and engine operating temperature. It's currently 9* F.

 

Wouldn’t sweat it. Make sure it’s between high and low lines, as suggested, and move on.

 

Yikes! Only reached the 20's for a low here so far.

 

Because my truck has a higher risk of head gasket failure, I check the coolant level more than your average Tacoma owner.
If it's between the high and low marks on the tank, you're good to go.

 

Follow up: For reference, it got down to about 29 degrees here overnight. It was about 36 degrees when I went out this morning to run an errand and checked the level before I started the truck. The coolant level in the bottle was approx 1" above the "Low" line.