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Failed Thermostat Housing/Coolant Loss Info Gathering

beardedGTI

Ready to race!
Location
Louisville, KY
Car(s)
2017 GTI Sport 6mt
Has anyone who has had theirs replaced gotten a bad/noisy one? During a recent service I complained mine was leaking and they pressure tested it and replaced thermostat housing and pump under warranty. Almost immediately after, I now have this intermittent low frequency whirring noise, almost like a bad bearing (or a pissed off hornet). However it only does it while the heat + fan is on. Coming from inside the dash area. I checked and I'm fairly certain it's not the blower. It seems like it is somehow related to the thermostat/pump replacement. Could this be the water pump? Is there another motor inside the coolant loop that could cause this? Air in the line maybe? I have tried my hardest to pinpoint it in the engine bay near the thermostat housing, but cannot over the noise of the engine.

"Well dummy, just take it back in to the dealer!"

Yes I will eventually do that. The problem right now is with covid and limited hours they are booked up for weeks. Took me about a month to get in last time and they had my car the whole day. Just trying to see if I can diagnose the issue in the meantime. I'm also prepared for the possible "this noise is within operating spec" even though it wasn't there before.

 

avenali312

Drag Racing Champion
Location
Mableton, GA
Car(s)
2015 VW GTI
Any idea if this part fails within a year, do they replace again, even if out of warranty?

Pretty sure they would as most dealers have a 1 year or 12k mile warranty on parts and work, at least that has been my experience. Lucky me, I'm now out of powertrain warranty and my 1 years is up since I had mine replaced. So, I'll be going the FCP Euro route next time it leaks (or fingers crossed, it just doesn't).
 

GTI_Jerm

Go Kart Champion
Location
SoCal
Pretty sure they would as most dealers have a 1 year or 12k mile warranty on parts and work, at least that has been my experience. Lucky me, I'm now out of powertrain warranty and my 1 years is up since I had mine replaced. So, I'll be going the FCP Euro route next time it leaks (or fingers crossed, it just doesn't).

Yeah, I just read the back stating that everything is covered under 12k/1yr warranty from day of install. My CEL was on when I left the dealership, but this morning it was off and is still off.. is that a thing?
 

avenali312

Drag Racing Champion
Location
Mableton, GA
Car(s)
2015 VW GTI
Yeah, I just read the back stating that everything is covered under 12k/1yr warranty from day of install. My CEL was on when I left the dealership, but this morning it was off and is still off.. is that a thing?

I'm not sure, maybe someone else can answer. I caught mine before the CEL came on.
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Yeah, I just read the back stating that everything is covered under 12k/1yr warranty from day of install. My CEL was on when I left the dealership, but this morning it was off and is still off.. is that a thing?

Yes that can happen.
 

mohammadsen

New member
Location
Canada
Car(s)
Mk7.5 GTI
Hey Guys, I just bought a 2018 GTI and I noticed that when I turn it off, I have white smoke coming out of the engine bay and it smells like coolant. The Coolant level looks to be right in the middle, so Im beyond confused. I was just wondering if you guys experienced the smoke coming out of the bay once you shut it off
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Hey Guys, I just bought a 2018 GTI and I noticed that when I turn it off, I have white smoke coming out of the engine bay and it smells like coolant. The Coolant level looks to be right in the middle, so Im beyond confused. I was just wondering if you guys experienced the smoke coming out of the bay once you shut it off

Welcome to the forum. Even when my thermostat housing was leaking I didn't see smoke when I shut it off. Next time you shut it off quickly open the hood and see where the smoke is coming from.
 

GTI_Jerm

Go Kart Champion
Location
SoCal
So I got my thermostat replaced and was wondering, what’s an acceptable “test-drive” mile wise? I came back to my car work 15 miles extra from when I dropped it off. I’d say 18/20 or so mechanics were young too, so I’m figuring one of em damn well went for a little joy ride.
 

mopar22

Go Kart Champion
Location
Va/MI
15 seems fine. I'd rather have 15 then 1/2. At least with 15, it has a better chance of getting up to operating temp so they'll really make sure it didn't leak when it opened/closed
 

Johaan

Passed Driver's Ed
Location
Atlanta
So for those of you that got it replaced, how long did it take for the smell to stop?

It’s been 3 days and smells stronger than before. My service advisor wants it back Monday, so they are not playing with it, but just wanted to get a sense of the community.

I’ve had the oil cooler, thermostat and housing replaced on mine, still no luck ... but all were confirmed leaking. The language for this last repair invoice is interesting: “Water pump seal has manufactured defect causing leak and overheat” Yup.
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
So for those of you that got it replaced, how long did it take for the smell to stop?

It’s been 3 days and smells stronger than before. My service advisor wants it back Monday, so they are not playing with it, but just wanted to get a sense of the community.

I’ve had the oil cooler, thermostat and housing replaced on mine, still no luck ... but all were confirmed leaking. The language for this last repair invoice is interesting: “Water pump seal has manufactured defect causing leak and overheat” Yup.
Only took a day of driving to burn off the smell.
 

GTI_Jerm

Go Kart Champion
Location
SoCal
Smell was gone the next day for me too, but is it normal for the tank to lose some coolant? I checked the other day and engine was up to temp, tank was barely above the minimum line, then I opened it up to top off and I guess I released pressure causing it to almost reach the max fill line. Not sure how this is supposed to work..
 

anotero

Autocross Champion
Location
Hither and thither
Car(s)
Mk7 GTI
Once the thermostat is installed, do I refill with coolant (I had about 4-4.5 liters come out), massage the hoses to have some air come out, then run the engine for some time so more air comes out, watch the coolant level drop, and refill again?
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Once the thermostat is installed, do I refill with coolant (I had about 4-4.5 liters come out), massage the hoses to have some air come out, then run the engine for some time so more air comes out, watch the coolant level drop, and refill again?


 
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