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Failed Thermostat Housing/Coolant Loss Info Gathering

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beejnt5

New member
Location
Montreal
Car(s)
2016 Golf 1.8 5mt
beardedGTI said:
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.

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Hey, did you ever find out what was causing that whirring noise? My 1.8 TSI started making the exact same sound after I got my turbo replaced by the dealer (due to a bad wastegate). 8 months prior to that, I had my thermostat housing replaced as well, but like I said, the noise only started after the new turbo install.

The whirring noise is also intermittent for me, and when it does happen, it's almost always after the car has been fully warmed up (oil temp around 100 deg C/ 212 deg F) and running at idle. You can have a listen here (the fan and heat were also off in this video):
 
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B

beardedGTI

Ready to race!
Location
Louisville, KY
Car(s)
2017 GTI Sport 6mt
beejnt5 said:
Hey, did you ever find out what was causing that whirring noise?
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I have not. I have since found that it looks like there is an auxiliary coolant pump in VW's:

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/water-pump/5q0965561b/
Is there a whining noise when your car is in idle? How about a coolant leak? If these symptoms are present, you need to check on the auxiliary water pump installed in your car. This pump helps to keep your coolant flowing in hot climates or under high loads on the engine or heating system.

In fact I seem to find posts that suggest that there may be 2 aux pumps, one for heater core and one for turbo. Someone seems to have located the turbo one here which sounds like could be related to your issue: https://www.golfmk7.com/forums/index.php?threads/aux-pump-issue.374782/page-2#post-7581749

I have an oil change coming up soon and going to ask the dealer about it.
 
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beejnt5

New member
Location
Montreal
Car(s)
2016 Golf 1.8 5mt
beardedGTI said:
I have not. I have since found that it looks like there is an auxiliary coolant pump in VW's:

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/water-pump/5q0965561b/
Is there a whining noise when your car is in idle? How about a coolant leak? If these symptoms are present, you need to check on the auxiliary water pump installed in your car. This pump helps to keep your coolant flowing in hot climates or under high loads on the engine or heating system.

In fact I seem to find posts that suggest that there may be 2 aux pumps, one for heater core and one for turbo. Someone seems to have located the turbo one here which sounds like could be related to your issue: https://www.golfmk7.com/forums/index.php?threads/aux-pump-issue.374782/page-2#post-7581749

I have an oil change coming up soon and going to ask the dealer about it.
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Thanks for the info! I had no idea these cars had a second coolant pump. Its placement in the engine bay definitely lines up with where I could hear the noise from behind my dash, so I think you've nailed it.

I'll definitely be keeping an ear out for the noise should it return and make sure I don't have any coolant leaking from that location either.
 
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Deleted member 112626

Guest
Yet another revision of this part... 06L 121 111 P
 
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codypka

Go Kart Champion
Location
New Jersey
Has anyone had luck getting the water pump/thermostat fixed outside of warranty? I'm at 69k, so 9k over. Got the low coolant light the other day. Fluid was about an inch below the minimum line. I topped up and it's been fine for 2 days, no leaks. I;m hoping its just normal loss, as my car has always burnt through coolant very slowly. But I don't have high hopes. It's never been this low
 
Ace92028

Ace92028

Go Kart Newbie
Location
San Diego
codypka said:
Has anyone had luck getting the water pump/thermostat fixed outside of warranty? I'm at 69k, so 9k over. Got the low coolant light the other day. Fluid was about an inch below the minimum line. I topped up and it's been fine for 2 days, no leaks. I;m hoping its just normal loss, as my car has always burnt through coolant very slowly. But I don't have high hopes. It's never been this low
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Depends on your dealer but, from my experience they will "try to work with you" and give you like 20-40% off the full repair job. Which is still more expensive than anywhere else.
 
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Chad M

New member
Location
Southern Alberta
geokilla said:
We actually have 5 year, 100k km powertrain warranty up here. So I have another 2.5 years and 52k km to go, assuming they don't say flashing a tune voids the warranty.
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Maybe it changed for '18, but my '17 had a 4yr. 80k km warranty (Alberta).

I waited until the last few days before my 4yr deadline @ 58k kms to have my thermostat housing changed under warranty. It leaked very small amounts almost since new, and I could always smell coolant under the hood. I'd estimate I lost approximately 20mm of fluid from the reservoir over the 4yrs combined.
 
johng.wissig

johng.wissig

Ready to race!
Chad M said:
Maybe it changed for '18, but my '17 had a 4yr. 80k km warranty (Alberta).

I waited until the last few days before my 4yr deadline @ 58k kms to have my thermostat housing changed under warranty. It leaked very small amounts almost since new, and I could always smell coolant under the hood. I'd estimate I lost approximately 20mm of fluid from the reservoir over the 4yrs combined.
Click to expand...
I'm at 82k. My level drops soooooo slowly and it never seems to reach the pavement. I've made a line on the reservoir and has not really moved since February .
 
Mk_GTI

Mk_GTI

Go Kart Champion
Location
Hellinois
Car(s)
2018 Golf R
Good news-
Brought my R to the dealer last week for some routine services and mentioned the coolant odor is still present and the tank level has dropped a bit. Pressure test showed a leak, so they replaced the water pump and thermostat housing assembly under warranty.
 
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Golfer883

Go Kart Newbie
Location
IL
Car(s)
19 GTI rabbit
ok so I called a few VW dealers and talked to parts department. When they look up my VIN it still shows the "M" version as the latest superseded part. They can't even get the "P" version, wonder where this info came from regarding this new revision?
 
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