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Failed Thermostat Housing/Coolant Loss Info Gathering

ReadTheBook

Autocross Newbie
Location
Bay Area Smoke Hell
Car(s)
2019 AT, 2018 S4
Edit 12/6/2019: Please file a complaint with the NHTSA for this issue using the following link, this would initiate the process for a recall.
https://www-odi.nhtsa.dot.gov/VehicleComplaint/?
Edit 2/3/2020: Please see post #153 for answers to a few questions one user had.

Edit 2/10/2020: Please see post #193 for another potential relevant cause of coolant loss

Edit 2/21/2020: As of now VW are still handing out revision M thermostat housings, per the repair on my wife's 2015 Golf SE. My 2017 Sport got the same part in April 2019.


For those interested, a thread has been started on the r/GolfGTI subreddit on Reddit.com asking for info about when your thermostat housing failed.

https://www.reddit.com/r/GolfGTI/comments/drna5m
Thought I'd put it here if folks want to contribute since so many of us have had this issue.

If you are not a Reddit user and wish to add your info, post it here I am happy to add it to the post for you. It would be tagged with your forum username and a link to your post here.
 
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avenali312

Drag Race Newbie
Location
Mableton, GA
Car(s)
2015 VW GTI
Not a Reddit user, so here you go.

2015 Volkswagen GTI DSG (non-PP)

Replaced by dealer under powertrain warranty on September 5, 2019 at 38,700 miles.

I have no idea if it was just the thermostat though. They didn't tell me the specific culprit. They replaced the water pump, aux water pump, and thermostat all at the same time.

Edit: Adding photo from work order.

 
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Carlosfandang0

Drag Racing Champion
Location
UK
Car(s)
2016 3Dr GTi DSG CSG
Not on reddit either,

2016 Golf GTi DSG, non P/P,

Replaced under VW Das Welt used approved warranty on 10/07/2019 at 39,205miles,

Paperwork states ‘remove and replace thermostat housing’

Water pump was not replaced but after inspection I’m pretty sure the actual thermostat is also new, although parts used are not stated on the invoice,

The leak was very minor but there none the less.
 

ReadTheBook

Autocross Newbie
Location
Bay Area Smoke Hell
Car(s)
2019 AT, 2018 S4
Not on reddit either,

2016 Golf GTi DSG, non P/P,

Replaced under VW Das Welt used approved warranty on 10/07/2019 at 39,205miles,

Paperwork states ‘remove and replace thermostat housing’

Water pump was not replaced but after inspection I’m pretty sure the actual thermostat is also new, although parts used are not stated on the invoice,

The leak was very minor but there none the less.

Not a Reddit user, so here you go.

2015 Volkswagen GTI DSG (non-PP)

Replaced by dealer under powertrain warranty on September 5, 2019 at 38,700 miles.

I have no idea if it was just the thermostat though. They didn't tell me the specific culprit. They replaced the water pump, aux water pump, and thermostat all at the same time.

Thanks guys. I've added your info.
 

JerseyDrew77

Autocross Champion
Location
Virginia & NC
Also not a Reddit user...

2016 GTI S 6MT

The housing failed at 61,200 and brought the issue to VWoA because the dealership refused to replace it WHILE I had warranty. In the end, VWoA covered the repair.
 

Jacobmk7

Go Kart Newbie
Location
NC
Car(s)
2015 GTI S 4dr DSG
2015 GTI 63k, at 45k brought it in to get it pressure tested and it passed twice. Vw refuses to cover it under warranty because it passed even though you could visually see dried coolant dripping down the block. Service advisor said “I gotta be honest with you man, it kinda looks like mud to me”, what a load of bs. Didn’t pursue any future action because the tech who did the pressure tests goes to my church and my uncle personally knows him.:rolleyes: I top up the coolant every oil change at 5k, no biggie.
 

ChronicSPD

Ready to race!
Location
Imperial MO
Mine has been slowly leaking since around 10k, it's at 28k now and I've topped off the coolant 3 times. I'll take it in soon, but it's hard since I'm the only person that has worked on (or driven) the car since it was bought new.
 

ReadTheBook

Autocross Newbie
Location
Bay Area Smoke Hell
Car(s)
2019 AT, 2018 S4
Didn’t pursue any future action because the tech who did the pressure tests goes to my church and my uncle personally knows him.:rolleyes:

No offense, but wtf does that have to do with anything? Who gives a F who knows who, you have a warranty and were denied for no reason on a well known issue that I've been directly told by my dealership is an acknowledged poorly made part from a shitty manufacturer. I'd have been livid. At the very least you should get your uncle to get that tech to do you a favor.
 

ReadTheBook

Autocross Newbie
Location
Bay Area Smoke Hell
Car(s)
2019 AT, 2018 S4
Mine has been slowly leaking since around 10k, it's at 28k now and I've topped off the coolant 3 times. I'll take it in soon, but it's hard since I'm the only person that has worked on (or driven) the car since it was bought new.

Yeah, that's more or less how mine went. I first noticed it was low at 5k when I did my first oil change. I ended up topping up every 3–5 months until it was worked on at ~25k.
 

Jacobmk7

Go Kart Newbie
Location
NC
Car(s)
2015 GTI S 4dr DSG
No offense, but wtf does that have to do with anything? Who gives a F who knows who, you have a warranty and were denied for no reason on a well known issue that I've been directly told by my dealership is an acknowledged poorly made part from a shitty manufacturer. I'd have been livid. At the very least you should get your uncle to get that tech to do you a favor.

Good point, but to me it’s not worth the hassle. Even if didn’t know the tech or anything, I would still have to jump through a bunch of hoops. It will most likely start leaking again in like 15k anyway, lol.
 

russiankid

Drag Race Newbie
Location
PA
My 2016 GTI S and my wifes 2015 Jetta SE both have had slight coolant loss/smell. Both were brought to dealer around 35k miles, pressure tested and found no issue. Coolant continues to slowly disappear.
 

aaronc7

Autocross Champion
Location
Clovis, NM
2017 Audi S3, 41k miles. Coolant will randomly drop a little low one day, and then be fine for weeks/months. One day there was a small puddle under the car in the garage. Seems to randomly leak vs slowly constantly over time.

Continuing to monitor for now. I have warranty left and open recall that needs done, but I've been putting it off since dealer is far away (passenger seat airbag switch recall).
 

ReadTheBook

Autocross Newbie
Location
Bay Area Smoke Hell
Car(s)
2019 AT, 2018 S4
2017 Audi S3, 41k miles. Coolant will randomly drop a little low one day, and then be fine for weeks/months. One day there was a small puddle under the car in the garage. Seems to randomly leak vs slowly constantly over time.

Continuing to monitor for now. I have warranty left and open recall that needs done, but I've been putting it off since dealer is far away (passenger seat airbag switch recall).

FYI, document what you find, when you find it, with photos so you can show your dealer.
 
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