Thermostat failing confirmed by VCDS logging

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
You can't be bothered with trying to beat a clock with big jobs, because you'll make a mistake and have to go back in and fix something that you overlooked.

This is this week's big one:



Engine replacement on a Lexus RX300. And the Cadillac CTS next to it is getting an evaporator core. The tech next to me and I had a pile of parts that were spread out across our whole side of the shop, LOL. :)

Fortunately, all the techs here have two workstations each, so if we have one big job going, we can sideline that to do something else minor. Inevitably a big job will require stopping for something, usually waiting on a part or whatever. In the case of this poor RX, being from the salt belt, it had some rust related issues upon disassembly. The shifter cable end was a ball of rust and broke immediately upon trying to remove it, and the ATF cooler pipes were rusted so thin they just crumbled when I went to remove the hoses. So I was waiting for those items for nearly a week. Had to come from Japan. Luckily the owner is away for a while, so I am not pressed for time anyway.
 
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oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Never a dull moment here. And I just got two TDI Beetles towed in for possible resurrection after sitting for years. :D
 

cliballe

Well-known member
Joined
Jan 21, 2010
Location
Tennessee
TDI
2010 Jetta
Wow, what a fun job!!! :eek: I got it done but it took me most of the day yesterday! I think the hardest part was getting the heater hose clamp off and back in place on the coolant pipe I was replacing.

I drove it around after the repair while monitoring the coolant temperature (G62) and now I'm getting up to ~95-96 degrees C again. I had a few "spikes" to 107 C (224F, and interestingly enough the dash gauge never moved LOL) but I attribute that to the new thermostat and purging out the air in the system. I'll monitor and log my temps on my 2hr drive later today and post those results.

A few pics:

Everything removed.


New Parts.


Going back together.
 

Henrick

Top Post Dawg
Joined
Aug 24, 2010
Location
Ireland
TDI
Golf VI TDI, 77 kW (CAYC)
Thanks for sharing. This inspires me to do the t-stat on my car too (probably along with TB and related components).

I am not going to remove the oil filter housing/coolant-to-oil heat exchanger because I believe that with the proper tool the pipe can be unscrewed with that element in place.

Also, did you have to remvoe the alternator? From the pcitures it looks like it's in place but just wanted to confirm. Service manual says you need to do so but I'd like to avoid that if possible.

EDIT: would be really nice if you could report back after some time with your observations if the MPG has increased after replacing the t-stat.
 
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cliballe

Well-known member
Joined
Jan 21, 2010
Location
Tennessee
TDI
2010 Jetta
I will caution you about trying to work around the oil filter housing. If you had a 1/4" drive 8mm(?) Triple Square bit you might be able to loosen and remove the bolt, but I don't think you'll have enough room to move the coolant pipe around like you need to remove it from the thermostat. The problem I think you'll have is the mounting tab for the coolant pipe is right next to another coolant port that comes out of the block (see picture below). You have to get the coolant pipe tab up and over that port to be able to remove the pipe from the thermostat. Without removing the oil filter housing I don't think there is enough room.



I did not have to remove the alternator, but I found it necessary to break out my 10mm 1/4" drive flex socket in order to get the bottom thermostat bolt out. The top one comes out easy with a standard 1/4" socket and ratchet. It is tight in there but doable.

Link to flex sockets I have:
http://www.sears.com/craftsman-18-p...lerId=Sears&prdNo=10&blockNo=10&blockType=G10

I hadn't noticed my MPGs suffering that much, but it was winter time too. I will post any findings that I experience.
 

Henrick

Top Post Dawg
Joined
Aug 24, 2010
Location
Ireland
TDI
Golf VI TDI, 77 kW (CAYC)
Thanks! Mine is 1.6 engine so there is a chance it's slightly different.

Also, I might be asking too much but it would be really nice if you could do some logging and post the warm up/drive temperature graph with the new thermostat. There are not much threads around here about these issues so this one could be one of a few complete threads.

Thank you
 

cliballe

Well-known member
Joined
Jan 21, 2010
Location
Tennessee
TDI
2010 Jetta
Thanks! Mine is 1.6 engine so there is a chance it's slightly different.

Also, I might be asking too much but it would be really nice if you could do some logging and post the warm up/drive temperature graph with the new thermostat. There are not much threads around here about these issues so this one could be one of a few complete threads.

Thank you
No, that's fine and yes I logged the warm up last night on my drive. I won't be able to post that graph until later today, but I did see steady readings once it was fully warmed up (92.7 C to 94.5 C) doing 60-70mph. It's definitely getting up to temp now.

Thanks for reporting back, and glad you got it fixed!
Hey, oilhammer, thank you for all the input you provided in helping me get prepped for this job. I look up to and respect you pros who do this stuff everyday!
 

cliballe

Well-known member
Joined
Jan 21, 2010
Location
Tennessee
TDI
2010 Jetta
Here's the graph after the new thermostat. Ambient temp was 47-49F over this two hour drive.

 
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Henrick

Top Post Dawg
Joined
Aug 24, 2010
Location
Ireland
TDI
Golf VI TDI, 77 kW (CAYC)


Initial "before" graph added for comparison.

Excellent thread, it has got all the info one might need.

Thanks for sharing.
 

cliballe

Well-known member
Joined
Jan 21, 2010
Location
Tennessee
TDI
2010 Jetta
I got this message after my 120 mile commute today (60-70mph), but I think I had a little bit of a tail wind. I usually see a maximum of 44.3 mpg on this same drive so I'm not contributing this mileage to the new thermostat.... yet.



Here are some of my hand calculated tank full averages for the last few fill ups (mixed hwy and city driving during Jan-Feb-Mar = cooler weather):

1/07/2018: 36.05
1/15/2018: 37.88
1/21/2018: 37.26
1/28/2018: 37.16
2/11/2018: 36.74
2/19/2018: 38.05
2/25/2018: 37.78
3/11/2018: 36.98
3/18/2018: 38.68

I may be able to see some improvement when I fill up on Sunday and moving forward. Will post up my findings as I get them.

EDIT:
03/25/2018: 39.63
04/01/2018: 39.28
04/08/2018: 38.76
04/15/2018: 37.40
04/29/2018: 36.98 (more around town than normal)
05/11/2018: 38.09
05/20/2018: 39.68
05/27/2018: 39.21
06/03/2018: 39.54
06/10/2018: 38.91
06/17/2018: 38.68
06/24/2018: 38.55
07/01/2018: 40.30 (more highway than normal)
07/04/2018: 39.90
07/08/2018: 40.88
07/15/2018: 39.84
07/22/2018: 37.46
07/29/2018: 36.98
08/05/2018: 38.06
08/12/2018: 37.18
08/19/2018: 36.87
08/26/2018: 38.18
09/02/2018: 37.51
09/09/2018: 39.57
09/16/2018: 37.83
09/23/2018: 37.58
10/05/2018: 36.46 (had emissions modification done this week)
10/15/2018: 37.24 (more highway than normal)
10/21/2018: 35.94 (48,000 miles of this is going to suck)
10/28/2018: 36.44
11/08/2018: 35.90
11/15/2018: 35.91
11/29/2018: 37.98
12/06/2018: 36.40
12/14/2018: 36.66
12/20/2018: 36.82
01/03/2019: 38.03 (more highway than normal)
01/06/2019: 35.96
01/13/2019: 35.80
01/21/2019: 36.70
01/25/2019: 35.17
01/30/2019: 36.12
02/08/2019: 34.88
02/12/2019: 36.28
02/20/2019: 34.22
03/05/2019: 35.06
03/14/2019: 33.36 (holy crap)
03/20/2019: 35.75
03/31/2019: 37.07
04/07/2019: 36.56
04/14/2019: 36.63
04/21/2019: 35.64
05/02/2019: 34.77
05/12/2019: 37.21
05/19/2019: 35.12 (Intermittent DTC: P0401)
05/27/2019: 35.57 (Intermittent DTC: P0401)
06/02/2019: 34.94 (Intermittent DTC: P0401, P2002)
06/09/2019: 34.59 (Intermittent DTC: P0401, P2002) Going to VW in the morning (They say new DPF needed. Parts ordered will call when in)
06/16/2019: 35.60 (Intermittent DTC: P0401, P2002)
06/24/2019: No Data because VW cleared trip memory during DPF and EGR Filter replacement.
07/04/2019: 34.68
07/07/2019: 37.90 (more highway than normal)
07/18/2019: 33.30
07/26/2019: 35.16
08/02/2019: 34.67
08/08/2019: 34.61
08/16/2019: 34.56
08/22/2019: 36.33
08/30/2019: 36.13
09/05/2019: 36.10
09/13/2019: 36.95
09/22/2019: 36.21
10/04/2019: 35.36
10/11/2019: 35.93
10/18/2019: 36.24
10/25/2019: 37.15
10/31/2019: 37.47
11/11/2019: 36.50
11/17/2019: 36.24
11/24/2019: 37.04
12/01/2019: 37.59
12/07/2019: 37.94
12/16/2019: 35.31
01/06/2020: 35.13
01/16/2020: 35.23
01/24/2020: 35.37
01/31/2020: 34.21
02/06/2020: 36.55
02/14/2020: 35.63
02/21/2020: 36.41
02/28/2020: 35.24
03/06/2020: 34.47
03/15/2020: 36.88
03/22/2020: 34.93
03/29/2020: 35.87
04/10/2020: 36.50
04/19/2020: 36.13
04/27/2020: 37.04
05/03/2020: 35.60
05/10/2020: 36.09
05/17/2020: 36.64
05/24/2020: 36.63
05/31/2020: 37.14
06/07/2020: 34.66
06/15/2020: 36.21
06/21/2020: 34.87
06/28/2020: 35.64
07/05/2020: 37.39
07/12/2020: 35.58
07/19/2020: 36.28
07/26/2020: 35.64
08/02/2020: 36.87
08/09/2020: 35.84
08/17/2020: 36.26
08/29/2020: 35.72
09/04/2020: 34.72
09/10/2020: 37.53
09/17/2020: 35.69
09/24/2020: 37.53
10/29/2020: 36.19
11/05/2020: 35.70
11/11/2020: 38.62
11/30/2020: 38.41
12/10/2020: 35.23
01/08/2021: 37.30
01/15/2021: 37.19
01/22/2021: 36.80
01/29/2021: 37.30
02/11/2021: 35.82
02/26/2021: 35.27
03/25/2021: 37.44
04/02/2021: 35.34
04/30/2021: 36.91
05/06/2021: 36.27
05/12/2021: 37.85
05/21/2021: 36.95
05/27/2021: 35.84
06/05/2021: 36.12
06/11/2021: 36.96
06/25/2021: 37.70
07/02/2021: 36.69
07/09/2021: 37.38
07/16/2021: 35.85
07/23/2021: 36.53
07/30/2021: 35.84
08/05/2021: 36.88
08/12/2021: 36.04
08/20/2021: 35.46
08/26/2021: 37.50
09/03/2021: 35.81
09/09/2021: 37.19
10/01/2021: 36.49
10/07/2021: 36.69
10/15/2021: 36.22
10/21/2021: 36.09
10/29/2021: 35.86
11/05/2021: 36.95
11/10/2021: 36.85
11/19/2021: 36.89
12/03/2021: 36.50
12/10/2021: 37.62
12/17/2021: 37.84
01/02/2022: 39.95 (more highway than normal)
01/14/2022: 35.63
01/21/2022: 37.96
02/03/2022: 38.37
02/11/2022: 36.19
02/25/2022: 37.40
03/04/2022: 35.40
03/18/2022: 35.96
03/25/2022: 34.73
04/01/2022: 35.87
04/08/2022: 36.37
04/17/2022: 36.14
04/29/2022: 35.64
05/06/2022: 35.96
05/13/2022: 35.35
05/20/2022: 36.13
05/27/2022: 34.48
06/03/2022: 34.27
06/09/2022: 37.38
06/17/2022: 34.61
06/23/2022: 35.23
06/30/2022: 36.04
07/07/2022: 35.22
07/15/2022: 35.00
07/22/2022: 33.44
07/31/2022: 37.56
08/07/2022: 35.24
08/14/2022: 37.54
08/21/2022: 36.04
10/14/2022: 35.60
10/21/2022: 36.74
10/28/2022: 37.28
11/04/2022: 36.19
11/10/2022: 36.98
11/18/2022: 38.07
12/02/2022: 35.92
12/09/2022: 35.06
12/16/2022: 35.41
12/22/2022: 36.65
12/31/2022: 37.37
01/06/2023: 37.54
01/13/2023: 37.46
01/20/2023: 37.25
01/27/2023: 36.25
02/03/2023: 35.27
02/10/2023: 36.89
02/16/2023: 36.48
02/24/2023: 35.41
03/03/2023: 37.62
03/10/2023: 35.83
03/15/2023: 35.96
03/17/2023: 36.97
03/22/2023: 36.75
03/31/2023: 37.07
04/05/2023: 35.81
04/28/2023: 35.35
05/12/2023: 36.78
05/18/2023: 38.17
05/26/2023: 38.59
06/02/2023: 38.01
06/09/2023: 37.64
07/01/2023: 35.86
07/07/2023: 36.95
 
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