I have suspected coolant issues. Just how bad it is?
Discussion
4 months back, I got a 2016 Polo GTI purchased SH @ 41k miles and have driven it a further 3k. It has been fine for all of this time until tonight.
Leaving work, an engine light pinged along with an accompanying message, 'Check coolant! See owner manual!'. I drove the thing home, and it was fine; no overheating and the car drove as normal.
5 mins after returning I stick the key in again and start the car; the message has gone. Still though, I was suspicious, and checked the coolant reservoir, which had lost at least half a litre which I have replaced.
Also, while it is hard to tell in the dark, the fluid appeared to be slightly brown and murky, though I can't say with absolute certainty right now.
Lastly, there is a wet white residue accumulated on the underside of the coolant reservoir cap. I also checked the oil cap but it is just coated with clean, honey-coloured oil as expected. I took a photo of this; https://i.imgur.com/DAJhlKn.jpeg
Leaving work, an engine light pinged along with an accompanying message, 'Check coolant! See owner manual!'. I drove the thing home, and it was fine; no overheating and the car drove as normal.
5 mins after returning I stick the key in again and start the car; the message has gone. Still though, I was suspicious, and checked the coolant reservoir, which had lost at least half a litre which I have replaced.
Also, while it is hard to tell in the dark, the fluid appeared to be slightly brown and murky, though I can't say with absolute certainty right now.
Lastly, there is a wet white residue accumulated on the underside of the coolant reservoir cap. I also checked the oil cap but it is just coated with clean, honey-coloured oil as expected. I took a photo of this; https://i.imgur.com/DAJhlKn.jpeg
The expansion tank cap has a relief valve which prevents overpressure. The fact that there's evidence of coolant loss there suggests that either the system is over-pressurising or the relief valve has gone bad.
First move IMO having topped up the coolant is to buy a new cap from VW and bung it on.
First move IMO having topped up the coolant is to buy a new cap from VW and bung it on.
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