Coolant mystery

[Cazthompson1996@gmail.com]

Hi guys,

Im having a strange problem with my 2007 1.25L fiesta, the coolant level keeps dropping to about half an inch below minimum but will not drop any further. It usually happens less than a day after topping up. There is no oil in my coolant and vice versa. There are no visible leaks that I can see, thermostat working fine and there are no cracks in my expansion bottle. The engine does not overheat due to this (thank god). When I start her up you can hear all the coolant sloshing around initially and then it settles down, you can mainly hear it from the passenger footwell. I have checked to make sure that the footwells arent wet, all seems good. Just a complete mystery to me. Has quite a few people stumped too. Any suggestions? TIA!

[Luke4efc]

1 minute ago, Cazthompson1996@gmail.com said:

and there are no cracks in my expansion bottle.

How have you checked this? The tanks are quite prone to failing with hairline cracks that you cant really see.

[Cazthompson1996@gmail.com]

19 minutes ago, Luke4efc said:

 

20 minutes ago, Luke4efc said:

How have you checked this? The tanks are quite prone to failing with hairline cracks that you cant really see.

The expansion bottle and the area surrounding it would be wet. It does seem to be the only logical thing but sadly it is not. 😞

 

[Cazthompson1996@gmail.com]

28 minutes ago, Luke4efc said:

How have you checked this? The tanks are quite prone to failing with hairline cracks that you cant really see.

Unless you have another suggestion as to how to check it?

[WES180]

If it has a hairline crack the water could be escaping under pressure more like a mist so as it hits the hot engine it would just evaporate leaving no visible trace as you said.

You could always tape or cable tie some kitchen roll or cardboard around the expansion bottle once you've topped the water up and then wait and see if it gets soggy.

Have you pulled the footwell carpet back and checked underneath for water? The sound insulation will hold a fair bit of water like a big sponge that might not have got through the carpet yet.

[Cazthompson1996@gmail.com]

On 3/21/2019 at 7:08 AM, WES180 said:

If it has a hairline crack the water could be escaping under pressure more like a mist so as it hits the hot engine it would just evaporate leaving no visible trace as you said.

You could always tape or cable tie some kitchen roll or cardboard around the expansion bottle once you've topped the water up and then wait and see if it gets soggy.

Have you pulled the footwell carpet back and checked underneath for water? The sound insulation will hold a fair bit of water like a big sponge that might not have got through the carpet yet.

Brilliant thank you, I shall have a proper look!

[btmaldon]

Have you tied changing the expansion tank cap? That may not be holding the full level of pressure and should be changed fairly regularly anyway.