Farmboy
Veteran Member
- Joined
- Jul 29, 1999
- Location
- Bloomington (Minneapolis), MN, USA
- TDI
- '15 Golf SE TDI 6spd 109k miles; '00 A4 NB 5spd 216k; '96 B4 Passat Sedan 220k
Yep. Coolant loss mystery.
Car purchased new August 2014.
2015 Golf TDI SE, 6 speed manual transmission.
I have topped off for a nag light (low coolant light) 6 times in roughly 8 years & 93k miles.
1 - 29,658 - 07/16/2016
2 - 34,480 - 12/15/2016
3 - 75,547 - 02/08/2021
4 - 92,799 - 06/25/2022
5 - 92,870 - 07/04/0222
6 - 93,186 - 07/23/2022
7 - 93,305 - 08/10/2022 (preventive fill, no nag light)
Never white or foam in oil. No obvious - to me - indication of coolant overflow at the plastic reservoir. Currently some white specking on the top of the plastic sphere that I suspect is due to my micro-spills & splashes while pouring. No obviously enormous - to me - pressure release opening the tank cap. Nothing else jumping out at me as a cause for concern or a way to narrow down my mystery loss.
At nag light #5 there was a tiny puddle on the ground in the garage under the right rear corner of the bottom engine cover.
I put the car up on ramps, pulled the bottom cover, got a bright light, and looked all over for witness lines showing a coolant leak path. There was no - to me - clear indication of where coolant had come from.
At nag light #6, I filled either all the way to the MAX or at least to a point roughly 1/2 way from MIN to MAX, didn't record properly in my log, don't recall for sure. I simply recall feeling frustrated at my inability to pinpoint the leak source and belief that "overfilling" was a livable trade-off until I've resolved the problem.
Today, top off #7, rather than wait for the nag light again, I filled to MAX as tank was at MIN. The car is mainly driven by my wife, a school teacher, so it's easy to let it mostly sit idle during the summer, as other projects are consuming time. Fall is coming, though, and my hope that the cause of this mystery coolant loss will make itself safely obvious is diminishing.
The only other weird coolant system thing that has ever happened is that the lower radiator hose popped off during my wife's commute shortly after the 10k complimentary dealer oil/filter change. Engine was shut down prior to catastrophic destruction, car was towed/flatbedded to the dealer, dealt with, and all subsequent oil changes have been by my hand.
If Bentley is available (print, CD, or whatever they sell now), I haven't purchased one yet, which means much of the engine & coolant system detail is still a mystery to me, if it's even well described in the Bentley, should it exist. I have looked through other threads here, and don't feel I've found any clear connection to any other reported issue. Could easily have missed something. If so, hopefully someone will gently and kindly point me in the right direction.
Based on my reading here, absent obvious alternatives, I'm giving serious thought to simply doing the timing belt, water pump, etc. now and see if maybe the WP is the culprit or something in that area, a connection, whatever.
My major question, after all that: Does anyone know this engine well enough to guess the most likely mystery loss point? Is the best guess water pump?
My minor question, go with OEM water pump or with a non-solenoid pump?
Other than that, anyone have any thoughts about anything I'm overlooking, should be planning to do to resolve this problem, etc.?
Until now this car has been a dream, now I'm starting to worry about the complexity & cost as it ages and truly requires attention, as compared to previous vehicles I've maintained and repaired for myself.
Thanks in advance
Car purchased new August 2014.
2015 Golf TDI SE, 6 speed manual transmission.
I have topped off for a nag light (low coolant light) 6 times in roughly 8 years & 93k miles.
1 - 29,658 - 07/16/2016
2 - 34,480 - 12/15/2016
3 - 75,547 - 02/08/2021
4 - 92,799 - 06/25/2022
5 - 92,870 - 07/04/0222
6 - 93,186 - 07/23/2022
7 - 93,305 - 08/10/2022 (preventive fill, no nag light)
Never white or foam in oil. No obvious - to me - indication of coolant overflow at the plastic reservoir. Currently some white specking on the top of the plastic sphere that I suspect is due to my micro-spills & splashes while pouring. No obviously enormous - to me - pressure release opening the tank cap. Nothing else jumping out at me as a cause for concern or a way to narrow down my mystery loss.
At nag light #5 there was a tiny puddle on the ground in the garage under the right rear corner of the bottom engine cover.
I put the car up on ramps, pulled the bottom cover, got a bright light, and looked all over for witness lines showing a coolant leak path. There was no - to me - clear indication of where coolant had come from.
At nag light #6, I filled either all the way to the MAX or at least to a point roughly 1/2 way from MIN to MAX, didn't record properly in my log, don't recall for sure. I simply recall feeling frustrated at my inability to pinpoint the leak source and belief that "overfilling" was a livable trade-off until I've resolved the problem.
Today, top off #7, rather than wait for the nag light again, I filled to MAX as tank was at MIN. The car is mainly driven by my wife, a school teacher, so it's easy to let it mostly sit idle during the summer, as other projects are consuming time. Fall is coming, though, and my hope that the cause of this mystery coolant loss will make itself safely obvious is diminishing.
The only other weird coolant system thing that has ever happened is that the lower radiator hose popped off during my wife's commute shortly after the 10k complimentary dealer oil/filter change. Engine was shut down prior to catastrophic destruction, car was towed/flatbedded to the dealer, dealt with, and all subsequent oil changes have been by my hand.
If Bentley is available (print, CD, or whatever they sell now), I haven't purchased one yet, which means much of the engine & coolant system detail is still a mystery to me, if it's even well described in the Bentley, should it exist. I have looked through other threads here, and don't feel I've found any clear connection to any other reported issue. Could easily have missed something. If so, hopefully someone will gently and kindly point me in the right direction.
Based on my reading here, absent obvious alternatives, I'm giving serious thought to simply doing the timing belt, water pump, etc. now and see if maybe the WP is the culprit or something in that area, a connection, whatever.
My major question, after all that: Does anyone know this engine well enough to guess the most likely mystery loss point? Is the best guess water pump?
My minor question, go with OEM water pump or with a non-solenoid pump?
Other than that, anyone have any thoughts about anything I'm overlooking, should be planning to do to resolve this problem, etc.?
Until now this car has been a dream, now I'm starting to worry about the complexity & cost as it ages and truly requires attention, as compared to previous vehicles I've maintained and repaired for myself.
Thanks in advance