MK 7.5 R wagon, expansion tank coolant level and it was down to the lower level.

[Call me Al]

I have been observing the expansion tank coolant level and it was down to the lower level.
I thought that it might just be expansion and drove from Brisbane to Mt Tamborine then Oxenford back to Brisbane.
The low coolant alert came on and I topped up the expansion tank with 225ml.
There has been no evidence of telltale leaks on the garage floor nor the engine bay. I got my sniffer hound to smell for sweet coolant but nothing to detect there.
So where does 225ml of coolant vanish to?
Should I suspect a thermostat water pump failure? Or the elbow at the back of the engine?
I have warranty with VW, should I report this to VW with photos.

Cheers Al

[7ur7le]

if it keeps doing it then the waterpump is most likely on its way out but not enough to have a visible leak

[Lucas_R]

Very very common issue on these engines. The waterpump/thermostat unit is made of plastic and either the unit itself develops a crack somewhere or the seal will leak.

The coolant will be no doubt dribbling down the front of the engine and onto the sump. Most of it will evaporate due to the engines heat but you will be able to find evidence of pink powder residue underneath the waterpump.

A new waterpump will set you back between about $1000-1500 depending on whether you use an aftermarket unit or a genuine unit (genuine costs more obviously) and labour cost.

I had mine replaced earlier this year and it was $1000 including labour using an aftermarket Geba branded unit. These units currently sell for $530 Geba Water Pump 11235/1 - Made in Germany | Run Auto Parts

Genuine units have recently had a price increase and are now around $900 (they were previously around $700) Water Pump & Thermostat Housing - Audi 8V & Volkswagen MK7 -EA888.3 — VAGPARTS Australia

[7ur7le]

you must have missed the key point that he has warranty from vw ... so after your little personal story.. he will pay $0

[Lucas_R]

you must have missed the key point that he has warranty from vw ... so after your little personal story.. he will pay $0

Yes I admit I missed that - so thanks for bringing that to my attention so politely as usual amunra.....cough...sorry, 7ur7le.

[doc_777]

I have no idea where the coolant goes on some engines. My son's Polo GTi (6c) had the pump and thermostat housing replaced under goodwill by VW and the selling (VW) dealer. Since then, there are no visible signs of leakage, the (awesome) VW specialist we see for that car cannot find any evidence of leakage, and somehow every 5 to 7 thousand kays, the reservoir takes up to a couple hundred ml's of top-up. It's like it disappears into an alternate universe.

My T-Roc (140TSI) had a drink of coolant about 6 months ago. No idea where it went. The level was perfectly stable before that, and it's been that way ever since.

My wife's car (Audi A4, 45TFSI) also seems to take a sip of coolant - about once every 15k km it needs maybe 100ml of top-up. Just enough that you notice, not enough to be a real issue.

Previous vehicles we've owned with the EA888 motor have not lost a drop of coolant.

I would bring it to the attention of VW if you are worried about it. The alternative is to track it for a while - see how long it takes for X amount of coolant to be consumed. Go from there.

I would be surprised if VW replaced the pump or thermostat housing without there being obvious signs of leakage - eg, a salty residue, or that coolant-coloured powdery residue that Lucas mentioned. Sometimes you need to look REALLY closely to see it - need the car up on a hoist, lower covers removed, and LOTS of light.

[7ur7le]

could be a slightly leaking hose / clamp that hasnt been tightened 100% accurately.. but not enough to to be visible .. they bubble away sometimes.. or a slight leak in waterpump/thermostat... not dripping but slightly leaking / bubbling

I have no idea where the coolant goes on some engines. My son's Polo GTi (6c) had the pump and thermostat housing replaced under goodwill by VW and the selling (VW) dealer. Since then, there are no visible signs of leakage, the (awesome) VW specialist we see for that car cannot find any evidence of leakage, and somehow every 5 to 7 thousand kays, the reservoir takes up to a couple hundred ml's of top-up. It's like it disappears into an alternate universe.

My T-Roc (140TSI) had a drink of coolant about 6 months ago. No idea where it went. The level was perfectly stable before that, and it's been that way ever since.

My wife's car (Audi A4, 45TFSI) also seems to take a sip of coolant - about once every 15k km it needs maybe 100ml of top-up. Just enough that you notice, not enough to be a real issue.

Previous vehicles we've owned with the EA888 motor have not lost a drop of coolant.

I would bring it to the attention of VW if you are worried about it. The alternative is to track it for a while - see how long it takes for X amount of coolant to be consumed. Go from there.

I would be surprised if VW replaced the pump or thermostat housing without there being obvious signs of leakage - eg, a salty residue, or that coolant-coloured powdery residue that Lucas mentioned. Sometimes you need to look REALLY closely to see it - need the car up on a hoist, lower covers removed, and LOTS of light.

[h100vw]

could be a slightly leaking hose / clamp that hasnt been tightened 100% accurately.. but not enough to to be visible .. they bubble away sometimes.. or a slight leak in waterpump/thermostat... not dripping but slightly leaking / bubbling

They dont have any hose clamps mate. Just the constant tension ones.

[7ur7le]

They dont have any hose clamps mate. Just the constant tension ones.

what is 'they'

[h100vw]

what is 'they'

All the hoses on a MK7

[7ur7le]

yeh, so, the rubber coolant hoses have hose clamps. the hose clamps are at a constant tension and if they are not placed correctly or the hose isnt connected properly it will have a slight leak.

no need to pretend youre some rocket scientist or brain surgeon

[h100vw]

Not being a rocket scientist. There's no hose clamps to tighten. They are either good or not.
I have fitted enough waterpumps on ea888 motors to know what I'm talking about.
What's far more likely if not the pump itself, is a failed plastic coupling.

[7ur7le]

Not being a rocket scientist. There's no hose clamps to tighten. They are either good or not.
I have fitted enough waterpumps on ea888 motors to know what I'm talking about.
What's far more likely if not the pump itself, is a failed plastic coupling.

good on you. for you to even say "theres no hose clamps to tighten" shows ur just here to flex ur w4ng.

there are in fact hose clamps to "tighten" and keep in the right position. they keep the hoses in tact and from leaking.. if a hose clamp is out of position or the hose isnt properly seated it can leak too under pressure. over a week or two of driving and leaking obviously causes you to lose fluid.

but keep arguing

[h100vw]

If we are being accurate in our statements, which is what I am doing.
If there's a leak due to a constant tension clamp. You cannot tighten it. You take it off and replace for a conventional worm drive hose clamp.

[7ur7le]

If we are being accurate in our statements, which is what I am doing.
If there's a leak due to a constant tension clamp. You cannot tighten it. You take it off and replace for a conventional worm drive hose clamp.

im not talking about a faulty hose clamp. im talking about a poorly placed hose clamp and/or refitted hose.. which can happen.. and a tension clamp can be tightened.. its tightness just cannot be adjusted. i ts either opened with pliers or closed / tightened.. if its tightened while incorrectly placed it will leak because its not properly sealing the hose.. very simple..