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Failed Thermostat Housing/Coolant Loss Info Gathering

GTIfan99

Autocross Champion
Location
FL
2019 Rabbit, 13,000 miles, can smell coolant any time engine is warm. Haven't lost an appreciable amount of coolant yet.

Has VW redesigned the thermostat housing or is this just going to happen again when people get it replaced? I assume the aftermarket has a better solution, why not do that?
 

ReadTheBook

Drag Racing Champion
Location
Bay Area Smoke Hell
Car(s)
2017 Sport, 2019 AT
2019 Rabbit, 13,000 miles, can smell coolant any time engine is warm. Haven't lost an appreciable amount of coolant yet.

Has VW redesigned the thermostat housing or is this just going to happen again when people get it replaced? I assume the aftermarket has a better solution, why not do that?
Keep a close eye on it. Check it in the same spot/conditions at the same time of day if you document it. If it fails, please document the failure with the NHTSA. There have been 2 revisions to the thermostat housing as far as I have come across. There isn't an aftermarket solution at this time as far as I've seen, but I haven't looked that hard either... I just haven't seen it come up in any of the threads I've started or posted in.
 

Boltsfan17

New member
Location
Tampa, FL
Update to update: Less than 24 hours after my warranty repair of a leaking thermostat housing, my car overheated and was forced to shut it down on the side of a very busy highway at rush hour.

Towed back to the dealer tonight. Await a new diagnosis and repair. Needless to say this dealer will be going out of their way to make this right.
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
2019 Rabbit, 13,000 miles, can smell coolant any time engine is warm. Haven't lost an appreciable amount of coolant yet.

Has VW redesigned the thermostat housing or is this just going to happen again when people get it replaced? I assume the aftermarket has a better solution, why not do that?
I don't know if they redesigned it but my warranty replaced thermostat housing hasn't leaked for 50,000 miles so far.
 

ReadTheBook

Drag Racing Champion
Location
Bay Area Smoke Hell
Car(s)
2017 Sport, 2019 AT
I don't know if they redesigned it but my warranty replaced thermostat housing hasn't leaked for 50,000 miles so far.
That is good to hear. Mine was first replaced a year ago this week. Leaked again a couple months later due to leaking oil cooler gasket (improperly put back together, apparently.)

I have just in the last few weeks started to notice that familiar odor and the fill was right at Max, which means I lost some coolant because the dealer had overfilled the car above max. I have started the process of documenting the issue over a period of months, again. :(
 

avenali312

Drag Race Newbie
Location
Smyrna, GA
Car(s)
2015 VW GTI
I don't know if they redesigned it but my warranty replaced thermostat housing hasn't leaked for 50,000 miles so far.
Do you have the work order and part number they used? Mine was replaced in September with the below.



I have just in the last few weeks started to notice that familiar odor and the fill was right at Max, which means I lost some coolant because the dealer had overfilled the car above max. I have started the process of documenting the issue over a period of months, again. :(
Mine was replaced under warranty four months ago and I've been watching the level slowly drop as well.
 

ReadTheBook

Drag Racing Champion
Location
Bay Area Smoke Hell
Car(s)
2017 Sport, 2019 AT
Do you have the work order and part number they used? Mine was replaced in September with the below.





Mine was replaced under warranty four months ago and I've been watching the level slowly drop as well.

I have the 06L-121-111-M thermostat currently as well. It was installed 05/29/2019. My first replacement I can't find the paperwork for but I swear it was L not M.

FWIW, I have found there are the following 6 previous part revisions:
06L-121-111-F
06L-121-111-G
06L-121-111-H
06L-121-111-J
06L-121-111-K
06L-121-111-L
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Do you have the work order and part number they used? Mine was replaced in September with the below.





Mine was replaced under warranty four months ago and I've been watching the level slowly drop as well.
I'll look for it tomorrow.
 

Boltsfan17

New member
Location
Tampa, FL
Hopefully final update: Temp redlined due to the tech failing to properly bleed the system causing an air bubble. I’ll check the part number on the warranty repair order on the thermostat housing.
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Hopefully final update: Temp redlined due to the tech failing to properly bleed the system causing an air bubble. I’ll check the part number on the warranty repair order on the thermostat housing.
I hope you shut it off right away. Put them on notice that if any problems arise from overheating that their responsible. Like a blown head gasket.
 

joeblonewjersey

Ready to race!
Location
Metuchen, NJ
Here is my concern. I bought the car new with expectations to keep it until I die or can no longer drive it. I never anticipated an issue like this. However, being it does exist, and I have less than 25k on my 2016 GTI-S, and I do smell anti freeze from time to time, and it's super minimal if almost indistinguishable in the tank (any drop), 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? One might think and wish to research in detail with VW (I may) as to if this is a well know issue and it is being taken care of as it seems to be from what I read here, 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? Additionally, if the parts in question have not been improved, has any 3rd part company manufactured the correct items so as the same issue do occur like the OEM parts, or is it all junk, prone to happen again, and I should consider dumping the car for the long term (disappointed). Generally a garaged highly maintained 2 dr. GTI-S that I thought would be my last car is now a worry. Also, from what I read hear there seems to be a lot of disassembly to get to the parts and does anyone have reservations or concerns that the factory certified and trained mechanics are competent enough to do a job as one might expect (as in perfect...everything)?
 

mopar22

Go Kart Champion
Location
Va/MI
Everything has been covered numerous time in this thread and many others for all the questions you have asked. In the nicest way possible if you can't even read up on this even a little bit and you're worried about it just then dump the car now
 

Boltsfan17

New member
Location
Tampa, FL
Well, more news on my overheating issue. Today while parked and idling the temp gauge climbed well beyond the midpoint heading towards the danger zone after about 5 minutes of idling. AC drops out and engine temp climbs quickly. When back out on the road the temp stabilized and AC seemed to work somewhat better.

Replicated the issue in the safety of my garage. Radiator fan underneath air box never came on while temp climbed. Called the service advisor and explained the issue. Beyond the massive apologies it was suggested the front radiator fan was not hooked back up and/or the new just warrantied thermostat housing was defective. He stated not all parts are perfect. Tomorrow will be my third appointment in less than a week. Patience is wearing super thin at this point. More to come....
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Well, more news on my overheating issue. Today while parked and idling the temp gauge climbed well beyond the midpoint heading towards the danger zone after about 5 minutes of idling. AC drops out and engine temp climbs quickly. When back out on the road the temp stabilized and AC seemed to work somewhat better.

Replicated the issue in the safety of my garage. Radiator fan underneath air box never came on while temp climbed. Called the service advisor and explained the issue. Beyond the massive apologies it was suggested the front radiator fan was not hooked back up and/or the new just warrantied thermostat housing was defective. He stated not all parts are perfect. Tomorrow will be my third appointment in less than a week. Patience is wearing super thin at this point. More to come....
Good luck. Make sure that they get the air out of the system also.
 

joeblonewjersey

Ready to race!
Location
Metuchen, NJ
Everything has been covered numerous time in this thread and many others for all the questions you have asked. In the nicest way possible if you can't even read up on this even a little bit and you're worried about it just then dump the car now
8 pages, no definitive in one place answers, cut and past, piece together the contributions and answers. I love forums.
 
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