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Failed Thermostat Housing/Coolant Loss Info Gathering

ReadTheBook

Drag Racing Champion
Location
Bay Area Smoke Hell
Car(s)
2017 Sport, 2019 AT
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!
Alright. I've really never seen anyone say this, and again, I've been following this issue in multiple threads on multiple forums for at least 4 years.

The caps are pretty f'n tight and I've also never seen anyone say they or a dealership observed, or show any proof of, any leaks at the expansion tank cap. I'd be quite interested to see those posts if you have links to them.
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Alright. I've really never seen anyone say this, and again, I've been following this issue in multiple threads on multiple forums for at least 4 years.

The caps are pretty f'n tight and I've also never seen anyone say they or a dealership observed, or show any proof of, any leaks at the expansion tank cap. I'd be quite interested to see those posts if you have links to them.
Those posts would have to exist first which makes it tough to link to them. ?
 

stuntnuts

Ready to race!
Location
Maine
Hey idiots who don't work on their own cars....

There is a pressure relief valve on the overflow cap itself. If the valve is failing, vapors escape. That's the coolant you smell under the hood. Eventually the vapor loss adds up to coolant loss.

Read the service manual, it states, when doing coolant pressure test, test the system and ALSO THE CAP. Dealership techs don't read manuals, they don't get paid enough flat-rate time by VW to do so, so they don't know to test the cap.

Look under your coolant bottle, and follow the frame rail. I bet you will see a dirty path that leads to the nose of the vehicle. That's where your coolant is going.
 

stuntnuts

Ready to race!
Location
Maine
This was a bit extreme considering a couple of people just asked for some links from you.
Cool.

Please continue driving your cars around aimlessly with a constant, persistent coolant smell/loss, while accepting the dealerships response that "they've tested your car and there's nothing wrong with it", instead of properly testing and replacing the actual defective $20 part that any one of you dealership-dependent sissies could do themselves.
 

avenali312

Drag Race Newbie
Location
Smyrna, GA
Car(s)
2015 VW GTI
Cool.

Please continue driving your cars around aimlessly with a constant, persistent coolant smell/loss, while accepting the dealerships response that "they've tested your car and there's nothing wrong with it", instead of properly testing and replacing the actual defective $20 part that any one of you dealership-dependent sissies could do themselves.
So, the trail of coolant from my thermostat down to the oil pan had nothing to do with it? Everyone in this thread just needs a new cap?
 

stuntnuts

Ready to race!
Location
Maine
So, the trail of coolant from my thermostat down to the oil pan had nothing to do with it? Everyone in this thread just needs a new cap?
In your case, you need a thermostat housing.

I'm just saying, in the case of the dealership "testing" and saying "there's no leaks in the system", they aren't lying....there is no leak in the "system". The leak is in the cap, which they are neglecting to test.

If they test your system and detect a leak at the thermostat housing, obviously that's the problem.

I'm just trying to provide a PSA to those of you that come up empty-handed.
 

avenali312

Drag Race Newbie
Location
Smyrna, GA
Car(s)
2015 VW GTI
In your case, you need a thermostat housing.

I'm just saying, in the case of the dealership "testing" and saying "there's no leaks in the system", they aren't lying....there is no leak in the "system". The leak is in the cap, which they are neglecting to test.

If they test your system and detect a leak at the thermostat housing, obviously that's the problem.

I'm just trying to provide a PSA to those of you that come up empty-handed.
100% agree with you and appreciate the way you typed up this reply. I think you'll find more accepting responses if you word your responses more like this one. The derogatory remarks and name calling are just going to trigger people and start unnecessary arguments.
 

stuntnuts

Ready to race!
Location
Maine
100% agree with you and appreciate the way you typed up this reply. I think you'll find more accepting responses if you word your responses more like this one. The derogatory remarks and name calling are just going to trigger people and start unnecessary arguments.
It's just frustrating when every time this topic comes up, I respond and tell them where the disconnect is, and no one hears me.
 

ReadTheBook

Drag Racing Champion
Location
Bay Area Smoke Hell
Car(s)
2017 Sport, 2019 AT
It's just frustrating when every time this topic comes up, I respond and tell them where the disconnect is, and no one hears me.
Once again, 4+ years following this issue, never once seen this mentioned. Sorry you're upset, but I asked you to show me where you said it so that I was informed... I started this thread as a resource for everyone after all.

You still haven't shown me or anyone else where you've said that and a search of this forum doesn't come up with anything posted by you on this topic. So, respectfully, please don't act all butthurt when nothing is even visible here on these forums and you're going around saying things like the above.

My personal experience and evidence I've seen in friends and relative's vehicles does not denote any issue with the cap. I've never noted any residues in either of my own MK7s or my in-laws MK7. I have never once seen someone post an image of residue coming from their cap and running along the engine bay.

Maybe there is some loss from the cap, but the thermostat housing is a very real and very big problem, and I don't think the cap could possibly account for the amount of coolant people are losing so quickly.

My service advisor specifically stated that the housings warp and flex over time due to heating and cooling, and they may not always show signs of leaking during test. They tested my car twice and my wife's car three times over the course of a a few years, all while coolant was needing topped up every 3-6 months, before they actually found the housing was finally in a warped enough position to be leaking during the test. I was told that they also needed to leave it pressurized overnight in both cases.
 
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fredothechimp

Passed Driver's Ed
Location
Bay Area, CA
Thanks for all your organizing on this ReadTheBook. I don't know if you've ever said, but which Bay Area dealers have you worked with on this issue? If you don't mind sharing.
 

ReadTheBook

Drag Racing Champion
Location
Bay Area Smoke Hell
Car(s)
2017 Sport, 2019 AT
I don't know if you've ever said, but which Bay Area dealers have you worked with on this issue? If you don't mind sharing.
Sure. Stevens Creek is where I go for warranty service. I've only done my wife's 6AT trans flush and a couple alignments done there as customer pay jobs because they had a coupon in all three cases. One of the alignments was on our MK1 and I know they have some old school techs who have experience with the older stuff. They even have guys who will work on air-cooled stuff.

I've been happy with them overall and they don't frown upon mods. They straight up told me 4.5 years ago, "As long as you're up front about stuff and don't send us on wild goose chases because your car is tuned and you didn't tell us, we are going to try to help you out as much as we can. We aren't about screwing over enthusiasts." Obviously YMMV.

When I go in my service advisor is interested in if I've done something else to the car. He really loved the Helix soundbox, CSS muffler, and suspension upgrades I've done.
 

dequardo

Drag Race Newbie
Location
Waukesha, WI
Cool.

Please continue driving your cars around aimlessly with a constant, persistent coolant smell/loss, while accepting the dealerships response that "they've tested your car and there's nothing wrong with it", instead of properly testing and replacing the actual defective $20 part that any one of you dealership-dependent sissies could do themselves.
Making friends and influencing people. Said no one.
 

amsr

Passed Driver's Ed
Location
Michigan
That’s interesting about the cap. My thermostat was replaced this past year and I still smell coolant - although the level hasn’t dropped that I can tell. I guess it could be leaking again, but the smell is mainly near the firewall on the passenger side right around the expansion tank. I don’t see any residue on/around the tank. Is the thermostat/water pump below this area? Maybe I should swap the cap just to see if it solves the issue...
 
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