Coolant overflowing

[Solsdad]

It looks like the coolant in my 2007 V6 is occasionally overflowing. 

 

I have done a sniff test to try to rule out the head gasket, and that was negative. 

 

What else could cause the coolant to overflow? 

 

 

[Rojie]

3 hours ago, Solsdad said:

It looks like the coolant in my 2007 V6 is occasionally overflowing. 

 

I have done a sniff test to try to rule out the head gasket, and that was negative. 

 

What else could cause the coolant to overflow? 

 

 

 

Hello Jason,

 

Welcome to the Forum.

 

Have you been topping up regularly ?

Any steam from the exhaust ?

 

You may have an air-lock.

Are there any signs of overheating ?

 

There is a procedure, somewhere in the Forum, on how to bleed the system.

 

There is a search box on your home page, top right.

[Solsdad]

I haven't topped up at all yet, as the level is still between the min and max. 

 

There's a bit of steam at start up, but that clears once it's warmed up. 

 

I haven't noticed the temperature gauge go up, it does smell a bit hot sometimes.

 

One thing is that I haven't noticed the fan running at all, so I need to check it is coming on when it gets hot. 

[Rojie]

On 4/15/2025 at 11:17 AM, Solsdad said:

I haven't topped up at all yet, as the level is still between the min and max. 

 

There's a bit of steam at start up, but that clears once it's warmed up. 

 

I haven't noticed the temperature gauge go up, it does smell a bit hot sometimes.

 

One thing is that I haven't noticed the fan running at all, so I need to check it is coming on when it gets hot. 

 

Could be the electric fan, that problem has also been covered in the forum quite recently.

 

I do not think running when the reservoir is almost on minimum is very wise.

 

[smurf]

Could be worth getting a new radiator cap. The coolant is released into the expansion tank as the engine warms up, and is drawn back in when it cools. However, if the cap is not sealing properly when the engine is not fully up to temperature it will spit hot water out until the cap seals. 

[Chris.ac]

I agree with smurf.

New cap is cheap.

If it is not sealing, you are reducing the boiling point and losing coolant. 

Check by loosely wrapping a clean white cloth around the overflow and cap on the reservoir, then checking for pink/red after a drive.

 

You could also have a hairline crack on the reservoir then expands when hot