GOLFMK8
GOLFMK7
GOLFMK6
GOLFMKV

Failed Thermostat Housing/Coolant Loss Info Gathering

Jonnymk7.5

Passed Driver's Ed
Location
NY
My 18 GTI coolant level goes down from full line to minimal line in 7k miles. Dealer did pressure test and couldn't find anything.
 

ReadTheBook

Drag Racing Champion
Location
Bay Area Smoke Hell
Car(s)
2017 Sport, 2019 AT
8 pages, no definitive in one place answers, cut and past, piece together the contributions and answers. I love forums.
What' to say they are not replacing with new, improved, upgraded, updated, corrected items so as it should not occur again from the same source or the same reasons after it is repaired to begin with?
Nothing other than if you have (at least) 7 known revisions of a part since 2013 EU launch, there would apparently seem to be a problem. We don't know what frequency the latest "M" part is or is not failing.

are they still using the very same replacement parts that are of the same production that is the cause of the defect or have the improved it?
None of us are VAG Engineers. Some people on this forum might currently or formerly work at a dealership, but it is unlikely they will be able to shed a ton of light on it. What I can tell you from my personal experience since I own 2 MK7s and won the leaking thermostat housing lottery 3 times thus far, is that my Service Advisor and Service Director, who are pretty straight shooters, would only share with me that it was a "supplier issue" and the superseded parts are supposed to finally address the issue.

Additionally, if the parts in question have not been improved, has any 3rd part company manufactured the correct items...
None that I am currently aware of and I have followed this issue on various forums/threads for ~4 years. The earliest thread I think I can recall is one on VWVortex in early 2015. I'm sure that someone will get around to doing an all aluminum assembly it eventually, but it does not look like a simple part.
Happy now?

I am also not sure if the thermostat would be covered under the CA emissions warranty that NJ is a part of.
 
Last edited:

joeblonewjersey

Ready to race!
Location
Metuchen, NJ
What' to say they are not replacing with new, improved, upgraded, updated, corrected items so as it should not occur again from the same source or the same reasons after it is repaired to begin with?
Nothing other than if you have (at least) 7 known revisions of a part since 2013 EU launch, there would apparently seem to be a problem. We don't know what frequency the latest "M" part is or is not failing.

are they still using the very same replacement parts that are of the same production that is the cause of the defect or have the improved it?
None of us are VAG Engineers. Some people on this forum might currently or formerly work at a dealership, but it is unlikely they will be able to shed a ton of light on it. What I can tell you from my personal experience since I own 2 MK7s and won the leaking thermostat housing lottery 3 times thus far, is that my Service Advisor and Service Director, whom are pretty straight shooters, would only share with me that it was a "supplier issue" and the superseded parts are supposed to finally address the issue.

Additionally, if the parts in question have not been improved, has any 3rd part company manufactured the correct items...
None that I am currently aware of and I have followed this issue on various forums/threads for ~4 years. The earliest thread I think I can recall is one on VWVortex in early 2015. I'm sure that someone will get around to doing an all aluminum assembly it eventually, but it does not look like a simple part.
Happy now?

I am also not sure if the thermostat would be covered under the CA emissions warranty that NJ is a part of.
Thank you for your summary overview, you have been extremely helpful.
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
My 18 GTI coolant level goes down from full line to minimal line in 7k miles. Dealer did pressure test and couldn't find anything.
Lots of guys have said the same thing even though their thermostat housing was leaking. They can simply do a visual check around the housing to see evidence of leaking.
 

Jonnymk7.5

Passed Driver's Ed
Location
NY
Lots of guys have said the same thing even though their thermostat housing was leaking. They can simply do a visual check around the housing to see evidence of leaking.
Next time I get my car serviced.Oil change. Will point that out. I do smell coolant under the hood.
 

avenali312

Drag Race Newbie
Location
Smyrna, GA
Car(s)
2015 VW GTI
I'm going to push the issue. Maybe replace thermostat or what's leaking.
Yeah, definitely get a visual on it. Mine was a slow leak as well and could have possibly passed a pressure test (speculating here since it was such a slow leak). But over the course of a few months, I went into the dealer with clear photographs showing the residue that had dripped all the way down to the bottom of the oil pan.
 

Jonnymk7.5

Passed Driver's Ed
Location
NY
Yeah, definitely get a visual on it. Mine was a slow leak as well and could have possibly passed a pressure test (speculating here since it was such a slow leak). But over the course of a few months, I went into the dealer with clear photographs showing the residue that had dripped all the way down to the bottom of the oil pan.
Mine passed the pressure test. Is there a revised part for this issue?. Hopefully it's taken care of. Still have time (warranty is good for another 4years 35k miles.
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Mine passed the pressure test. Is there a revised part for this issue?. Hopefully it's taken care of. Still have time (warranty is good for another 4years 35k miles.
I don't know if there's a revised part but mine hasn't leaked in 50,000 miles since it was replaced.
 

stuntnuts

Ready to race!
Location
Maine
I've said this a million times here, but it always falls on deaf ears.......HAVE THEM PRESSURE TEST THE CAP, NOT JUST THE SYSTEM!
 

avenali312

Drag Race Newbie
Location
Smyrna, GA
Car(s)
2015 VW GTI
Mine passed the pressure test. Is there a revised part for this issue?. Hopefully it's taken care of. Still have time (warranty is good for another 4years 35k miles.
Per @ReadTheBook, there have been 7 revisions of the part since the MK7 inception in the EU. The current one that seems to be installed is the part number that ends in "M."
 

Godspeed!

New member
Location
Louisiana
2017 GTI PP 6mt, 33k miles. Certified Preowned. Tracked and documented coolant loss for about 8 months. Was diagnosed last week at dealership, parts ordered. At dealership now for warranty replacement t/stat - wp assy.

I'll report back with part numbers and summary of dealership experience. So far all is well.

Godspeed!
Dave
 

ReadTheBook

Drag Racing Champion
Location
Bay Area Smoke Hell
Car(s)
2017 Sport, 2019 AT
2017 GTI PP 6mt, 33k miles. Certified Preowned. Tracked and documented coolant loss for about 8 months. Was diagnosed last week at dealership, parts ordered. At dealership now for warranty replacement t/stat - wp assy.

I'll report back with part numbers and summary of dealership experience. So far all is well.

Godspeed!
Dave
Thanks. Please be sure to report this, and any subsequent issues, once the repair is completed. File a Vehicle Safety Complaint | Safercar.gov | NHTSA
 
Top