VW Golf Mk 7.5 2.0 TDI Slow Loss of Coolant

[Rocky95]

Hi all,
I've been having a slow loss of coolant. In the attached picture you can see how high it was on the 5th October 2023 vs today (22 January 2024). I noticed a small loss prior to October, which I took the car to the mechanics for. They could't find a leak anywhere obvious. I don't want to keep pestering them every time I find a small problem, they've been very kind so far to not to charge me for these check ups without any repairs done.

Is this loss of coolant over a 3 month period worth getting checked out? Can it and what sort of damage could this do to my engine or components?

The only abnormal thing I notice with my car is that every now and again while I'm driving there will be a sudden/split second loss of power, but this could be something else (EGR??).

My car specs:
2017 VW Golf Estate (MK 7.5) 2.0 TDI (Euro 6, non adblue version).

Thank you

[Aunty Pasty]

I also found I had a similar issue with my Golf Mk7. This occurred even after the thermostat housing was replaced under warranty. For that slow level drop I would just keep an eye on the level and top it up regularly.

[Belle427]

Water pump maybe.

[Nemophilist]

Similar experience here.
It’s had thermostat and new header tank even.

No other symptoms so I just keep an eye on it.

It appears to be a mystery for now

[shtu]

I had similar when I had a Golf GTD, and even pressure-testing it didn't reveal the cause. Never had any running, heating or cooling problems in 4 years, just lost a little coolant somewhere.

I ended up just topping it up once in a while. 2-3 times a year maybe.

[Sslink]

I had a similar problem on a Mk7 Golf some years ago.

Turns out I had a hairline crack in the EGR cooler.

The car would run fine until it was up to temp, and then I imagine the increased temp raised the pressure within the system and it would dump the entire reservoir into the exhaust, creating a steam locomotive effect.
The sound of the "Warning Low Coolant" chime still makes me sweat bullets.

So I'd investigate the EGR Cooler, the Charge cooler, themostat housing and the waterpump (especially if it's not been replaced yet, usually replaced along side the cambelt at 5 years or 120k miles, which personally I think is a bit too long..)

So whilst the coolant loss is still relatively minor, I wouldn't put off remedial works for too long, if it drops all the coolant in one go and you aren't in a position to stop immediately you could do major damage to the motor.

[Dr G]

Sslink said:

EGR cooler.

Beat me to it. This is often the source of "invisible" coolant leaks.

[Rocky95]

Thanks for all the comments people, huge help!
I think what I'll do is I'll keep an eye on it for now and do a big overhaul when it comes to change the belt, waterpump and change extra components in the hope that it fixes the problem.

Cheers

[Nemophilist]

Mine went from a slow loss of coolant over the past year to a sudden loss of coolant yesterday.

Looks like the radiator is the cause. Have it booked in to get fixed in a week. Now just got to work out how to get it to the garage which is 9 miles away