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Looking at my late 2014 184 I can see two pumps listed - but its not clear which is for which job?

04L965567A Coolant pump PRE2,DK7
5Q0965561B Additional coolant pump PIERBURG
 
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And the number which you posted is for the charge cooler pump, I have already replaced that.
It is, and the part number i posted is for the pump you asked for ! Near the oil filter housing.

 
Evening all.

I have exactly same issue as OP

- There is water sloshing noise behind the middle vents/dash when you trun off engine, or if ignition is on I can hear like a faint water run/slosh sound
- pressure is building up and coolant it's being forced out of the expansion tank after turning engine if its filled to a max level.

- Coolant is also not being sent back to expansion tank properly at times (I think this is the case because when I undo the expansion tank cap the coolant comes rushing back and fills past the minimum line)

- I have replaced the expansion tank cap ( without silica bag , original expansion tank bag is intact)

- My heating in the car is very warm on highest temp, and there isn't really a temperature difference between the left side and right side of the car
and the temp readings always stable at 90C

- The coolant loss/drop is very sporadic (irregular) sometimes its stay at minimum or bellow sometimes its forced out by pressure build up.

I did pressure test : it does not drop ( assuming it happens only when pipes are hot and expanding no pressure loss on cold engine

I did head gasket leak test nothing ( it was a pheew moment)

Now thing is there was no visible leak however after adding a coolan dye I noticed there was a slight spotting marks around the clamped areas where metal pipes meet rubber ( markt by the red arrows in picture ) so I suspect O rings. does anyone know correct part numbers for those 2 ?

also will small spotting would be enough to build that pressure that pushed out coolant after engine is off ?

I saw someone mentioning secondary pump how to test it if its seal gone etc ?

any other advice much appreciated I'm goin mental with his!

1789757657273.png
 
I'd say replace your heater matrix and see what happens. Sounds like there is a blockage somewhere. Mine made similar noises when mine was blocked. The system over pressurised during a DPF regen and exiited via the pressure valve in the expansion tank lid.

The car 3 has 3 coolant systems/circuits and 3 pumps - the main one for the engine and radiator and 2 auxillery pumps for the charge cooler and heater matrix/egr cooler circuit.

Can't say for sure what your problem is but I would certainly consider changing the matrix and see what it does after that.
 
Evening all.

I have exactly same issue as OP

- There is water sloshing noise behind the middle vents/dash when you trun off engine, or if ignition is on I can hear like a faint water run/slosh sound
- pressure is building up and coolant it's being forced out of the expansion tank after turning engine if its filled to a max level.

- Coolant is also not being sent back to expansion tank properly at times (I think this is the case because when I undo the expansion tank cap the coolant comes rushing back and fills past the minimum line)

- I have replaced the expansion tank cap ( without silica bag , original expansion tank bag is intact)

- My heating in the car is very warm on highest temp, and there isn't really a temperature difference between the left side and right side of the car
and the temp readings always stable at 90C

- The coolant loss/drop is very sporadic (irregular) sometimes its stay at minimum or bellow sometimes its forced out by pressure build up.

I did pressure test : it does not drop ( assuming it happens only when pipes are hot and expanding no pressure loss on cold engine

I did head gasket leak test nothing ( it was a pheew moment)

Now thing is there was no visible leak however after adding a coolan dye I noticed there was a slight spotting marks around the clamped areas where metal pipes meet rubber ( markt by the red arrows in picture ) so I suspect O rings. does anyone know correct part numbers for those 2 ?

also will small spotting would be enough to build that pressure that pushed out coolant after engine is off ?

I saw someone mentioning secondary pump how to test it if its seal gone etc ?

any other advice much appreciated I'm goin mental with his!

View attachment 55349
Does this seem to happen after a regen ? If so as said above by BillyCool look at the wiring on the charge cooler pump.

This pump is the one near the oil filter, the wiring can get easily damage or dislodged after a oil change. Also check the pump phisically runs you can do this in VCDS or just stick a 12 volt feed to it off the battery. If this pump does not run when needed the coolant in the charge cooler boils and the pressure empties your expansion tank.
 
Now thing is there was no visible leak however after adding a coolan dye I noticed there was a slight spotting marks around the clamped areas where metal pipes meet rubber ( markt by the red arrows in picture ) so I suspect O rings. does anyone know correct part numbers for those 2 ?

Regarding this point: I changed my inlet manifold - and after doing so, had a weep out of the right hand pipe you highlighted. Turns out the spring clip had weakened and lost some of its tension! New spring clip and fixed the leak.
There are no o-rings for the areas you are highlighting. Just metal spring clips.

1789978661272.png


I would also double check your header tank/cap/o-ring pressure rating - by isolating the tank, and pressurising one of the ports - to check the cap holds and releases at its rated pressure.
I had fitted a new tank and cap a while back - and found after chasing a slow leak the o-ring didn't have a great fit and had slightly flattened - so a new o-ring fixed my slow leak.
 
Does this seem to happen after a regen ? If so as said above by BillyCool look at the wiring on the charge cooler pump.

This pump is the one near the oil filter, the wiring can get easily damage or dislodged after a oil change. Also check the pump phisically runs you can do this in VCDS or just stick a 12 volt feed to it off the battery. If this pump does not run when needed the coolant in the charge cooler boils and the pressure empties your expansion tank.
Funny you say that, after normal drive it drops low while engine is running BUT overspill from expansion tank once engine is off.
After regen it stays bellow minimum untill I open expansion tank lid and then is swoosh back up to level it was before.

thanks for the tip with wired from battery pump running saved me this worry .
 
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Regarding this point: I changed my inlet manifold - and after doing so, had a weep out of the right hand pipe you highlighted. Turns out the spring clip had weakened and lost some of its tension! New spring clip and fixed the leak.
There are no o-rings for the areas you are highlighting. Just metal spring clips.

View attachment 55366

I would also double check your header tank/cap/o-ring pressure rating - by isolating the tank, and pressurising one of the ports - to check the cap holds and releases at its rated pressure.
I had fitted a new tank and cap a while back - and found after chasing a slow leak the o-ring didn't have a great fit and had slightly flattened - so a new o-ring fixed my slow leak.
I have changed expansion tank cap recently altogether with expansion tank ( got one without that stupid silica bag as my mates wag got issue after that bag ripped and clogged up system.

this is why I have trust issues with AI ... it stated there is O-rings ..lying ******* :D got clamps on order I do hope its just silly as that and it just gets depressurized don't hold vacuum therefore all this nonsense with gurgling and jumping level of coolant .