Coolant behaviour question

[kernnowkarmann]

Hi all, had major service about 3 months ago including new water pump etc.

In last week have done about 2.5k km. Mainly in 3 long journeys from Luxembourg, going to and from alps and today 1k km going to North of England.

Stopped at service station about 200km from destination and when started engine the coolant light came on and it told me to check it. I had checked before first long journey and all fine so was surprised to see it had dropped about halfway down the tank.

Went into garage and bought some coolant. Knowing you have to be careful if engine not fully cool I started undoing the cap slowly. Before it was off it made a kind of hissing sound and the coolant level came back up to normal.

When restarted, no warning! Checked after 100km and coolant still at normal level.

Does anyone know why this would have happened?

Thanks! (And the van drives like a dream on these long journeys!)

 

[WelshGas]

Hi all, had major service about 3 months ago including new water pump etc.

In last week have done about 2.5k km. Mainly in 3 long journeys from Luxembourg, going to and from alps and today 1k km going to North of England.

Stopped at service station about 200km from destination and when started engine the coolant light came on and it told me to check it. I had checked before first long journey and all fine so was surprised to see it had dropped about halfway down the tank.

Went into garage and bought some coolant. Knowing you have to be careful if engine not fully cool I started undoing the cap slowly. Before it was off it made a kind of hissing sound and the coolant level came back up to normal.

When restarted, no warning! Checked after 100km and coolant still at normal level.

Does anyone know why this would have happened?

Thanks! (And the van drives like a dream on these long journeys!)

A build up of pressure within the coolant system causes pressure expansion of all coolant pipes and if high enough even the coolant radiator thus increasing the volume of the coolant system and hence a drop in fluid level.
Open coolant expansion cap, pressure drops , volume of coolant system returns to normal and fluid level rises.

So, what is causing the pressure to rise in the coolant system?

The coolant system is pressurised to a degree, normally. Coolant as it heats up increases in volume, hence the expansion tank , but not to the degree you mentioned.

It could be something simple or something more significant.

Air lock from water pump change?
Faulty pressure cap on expansion tank?
Gas leak into coolant system?

 

[Perfectos]

Had a new water pump etc when cam belt was done .

Indie deliberately over filled (visual on expansion tank) ! Told me the level will drop !

it did back to Normal !
its a thing

 

[Hawthorn37]

I’d get this checked out by a mechanic. The coolant system in a modern car is split into two parts, pressurised and atmospheric. The pressurised part ensures that water doesn’t boil at the working temperature of the engine. The atmospheric part is topping up any water losses via the header tank. It appears you’re getting pressure in the header tank which isn’t right. I’ve not observed the situation you’re describing on any of our vehicles.

 

[kernnowkarmann]

Just thought I'd share the video of what happens when cap removed from coolant. This is with a cold engine a day or so after last used

 

[kernnowkarmann]

Update:

Fixed, was the EGR coolant pump (might not be the correct terminology, struggled a little with the translation...)

Still, expensive at a tad under €2000

Windscreen developed a massive crack though so at least that got changed as well, love a new screen without all those tiny chips... (looks on the bright side and tries to ignore engine cost)

 

[Hawthorn37]

Update:

Fixed, was the EGR coolant pump (might not be the correct terminology, struggled a little with the translation...)

Still, expensive at a tad under €2000

Windscreen developed a massive crack though so at least that got changed as well, love a new screen without all those tiny chips... (looks on the bright side and tries to ignore engine cost)

Good to have your update, it could help others in the future. Sorry it’s been an expensive solution though, but at least you have some peace of mind now.

 

[kurienp]

Update:

Fixed, was the EGR coolant pump (might not be the correct terminology, struggled a little with the translation...)

Still, expensive at a tad under €2000

Windscreen developed a massive crack though so at least that got changed as well, love a new screen without all those tiny chips... (looks on the bright side and tries to ignore engine cost)

If you don't mind me asking - at how many kilometers did you have to change the EGR pump? Also, hope they changed both the EGR cooler and the EGR pump. Looking at the cost it seems they have done both. I think it comes as a single unit.

Sent from my Pixel 6 Pro using Tapatalk

 

[kernnowkarmann]

If you don't mind me asking - at how many kilometers did you have to change the EGR pump? Also, hope they changed both the EGR cooler and the EGR pump. Looking at the cost it seems they have done both. I think it comes as a single unit.

Sent from my Pixel 6 Pro using Tapatalk

The van has done 72,000 km. The problem first occurred about 5,000 ago though, I did 5 long (750+km) journeys topping it up before I could get it fixed, in this time it definitely started to get worse though

 

[kurienp]

The van has done 72,000 km. The problem first occurred about 5,000 ago though, I did 5 long (750+km) journeys topping it up before I could get it fixed, in this time it definitely started to get worse though

I am at 51000 and got an egr error. Now it is gone, but will replace both EGR cooler and pump in the next few months.

Sent from my Pixel 6 Pro using Tapatalk