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Coolant leak

Heathy

Passed Driver's Ed
Location
Hull, East Yorkshire
Car(s)
MK7 VW GTD
Around 1.5 weeks ago I got in my car at night and a low coolant warning came on my dash, had a look but coolant tank looked full so didn't drive it and checked it the next day morning. The coolant tank was completely empty and the tank was orangey in colour with residue stains. I just topped it up with some cheap coolant I could quickly get hold of and got it taken into a garage for a interim service and they also had a look and said the expansion tank was cracked, so I've ordered a new one, which I was planning on fitting this week.

Then a few days ago I saw a massive puddle of coolant as I parked up (see photos), although the coolant didn't seem to drop much in the expansion tank over the next couple of days, then last night I got in again and the warning came on again, no coolant in the expansion tank apart from the sludgey mess in the photos, it also smelt bad so I'm fearing some kind of combustion gases are entering the coolant (hoping thats not the case, I have ordered a gasket test kit).

I don't know what this could be, you can see the coolant around the tank, the coolant looks rusty with small white flakes in it, wasn't sure if the silica bag could have burst or if this could be because of mixing coolants or old burnt coolant, I was going to get the coolant flushed and changed after putting the new tank on but now I think theres another much worse cause for the leaking, do you think it's still worth putting the new tank on yet?

I was going to wait and see what happens with the combustion gas test when that comes but given it's easter I can't get my car into a VW specialist while late next week.

Was hoping someone may have had a similar issue and help me identify what is going on?

Water pump was done in November last year too. Not noticed any other issues like white smoke, overheating or power issues, car drives fine, does seem to be doing lots of regens lately though and I have noticed more trouble starting but that seems to have improved so probably not connected.
 

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Last edited:

Heathy

Passed Driver's Ed
Location
Hull, East Yorkshire
Car(s)
MK7 VW GTD
No gases detected so that’s good, new tank fitted, going to see how it goes over the next few days, still expecting it to leak again and my coolant to turn shit from all the crap coolant already in the system but if it stops leaking then I’ll be getting the coolant system flushed and replaced.
 

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Heathy

Passed Driver's Ed
Location
Hull, East Yorkshire
Car(s)
MK7 VW GTD
Updating this again as I really want to ge this sorted and struggling to find any info on my specific issue.

Had two garages look at the car now, both pressure tested it and couldn't find any external leak, they couldn't see any leaks from the water pump or thermostat but within 300 miles the coolant warning light came back on and the reservoir is empty, theres obviously a leak somewhere.

It's like it seems fine then one day I will get in the car and the warning comes on with no coolant, usually seen large puddles on the floor too, it's like something is maybe pressuring the system and it leaks out then, I don't think it's leaking through the exhaust or anything as it is clearly visible that liquid is coming from somewhere. I also managed to take the trim off in the car to see the heater matrix no signs of a leak there either, it doesn't seem to be a head gasket issue or cracked cylinder head as the symptoms I've read up on those don't seem to match.

If any one can help I'd really appreciate it as my only option now seems to be selling the car on.
 

2018gti

Drag Racing Champion
Location
Massachusetts, USA
Car(s)
Golf GTI Autobahn MT
does the GTD have the coolant adapter right in front of the turbo, on the head, like the GTI’s? that’s the only thing I can think of, I had a very small leak coming from there. I guess you’d already have noticed though since if it leaks from there it’s usually steaming.
 

Heathy

Passed Driver's Ed
Location
Hull, East Yorkshire
Car(s)
MK7 VW GTD
does the GTD have the coolant adapter right in front of the turbo, on the head, like the GTI’s? that’s the only thing I can think of, I had a very small leak coming from there. I guess you’d already have noticed though since if it leaks from there it’s usually steaming.
I'm not sure, I will try and have a look but I've not seen anything, I feel like the only thing I could try is to replace the heater matrix as I do only have heat on one side of my vents and I have been sometimes hearing a gurgling sound from behind the dash as I turn the engine off, also occasionally smelt coolant so I wondered if the silicone bag could have burst and partially blocked the matrix, I've never really checked before but the trim next to the heater matirx is hot to touch, although I m not sure if thats normal or not.

I would have thought any type of blockage would have shown up on a pressure test though, I feel like when I first bought the car it was losing coolant, and I do remember them saying they changed the heater matrix, whether that was just one part of many I can't remember.
 
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