My V8 (I know, different motor) needed a little time until the air got purged after a complete drain and refill of the cooling system. It took 1 or 2 drive cycles, IIRC, to "self purge".

Now, most newer cars require an air purge of the cooling system any time it's opened up.
:- /

 

Thanks for the reply. We have driven it 4 days totaling 7 drive cycles. The first 4 were fine and the last three had an overheat. I think you are right that it is an air bubble. I just ordered the vacuum fill kit from ECS tuning. Hoping I don't have to drain the system first.. there is no good way of draining and catching the coolant. Opening the lower radiator hose only empties the radiator unless the system is hot enough for the thermostat to be open. Cheers.

 

i have the same problem with my 2012 3.0tdi, no solution yet. Did you find a solution.
Link for my problem: http://www.clubtouareg.com/forums/f...3-0tdi-engine-overheating-no-hot-air-irregular-coolant-loss-problem-254722.html

 

Interesting. The history seems to indicate this may be an old problem that hasn't been solved, but that isn't original to the vehicle (think engine casting defect) and stemmed from some unknown event. Was the thermostat OEM or some aftermarket job (only buy OEM).

Was the secondary pump (the electric one) one of the items that didn't make it to the T3? Might check this (if you have it).

Seems clearance related...like something is making the thermostat stick part of the time. Have you done a proper pressure coolant flush? Not just a drain and fill. Someone could have put some leak fix crap in your system at some point and it could have gummed stuff up??

Whatever it is is sure odd.

Another strange solution...(doesn't fit your issues...just is interesting) is someone had a radiator where the vanes were packed full of mud from offroading. A careful wash fixed his (again not your issue).

 

Was the secondary pump (the electric one) one of the items that didn't make it to the T3? Might check this (if you have it).

This from page 56:

 

Thanks all for the replies. We have had about 14 successful drive cycles now without any overheat. Meanwhile, the cooling system vacuum tool came... I did not pull a vacuum on the system nor did I re-drain the system and do a proper flush. I will if it overheats again. Here are some shots at the questions I missed.

- The old thermostat was definitely broken and came out in three pieces. The plastic was white.. I didn't check to see if it was OE. The replacement thermostat I bought was from RockAuto and was not OE. It was easy enough to replace if it does fail (as long as I don't warp a head if it does go).
- The overheat after the thermostat replacement was most likely a bubble in the system. I did not have the vacuum tool when I refilled the system so it was not filled correctly. I think the bubble was somewhere in the heater core since cool air came out of the system briefly when the system was at temperature (yes I turned the heat and fan on to ensure heater core valve was open before filling the system). The system must have successfully self bled the air bubble out over three days.
- I don't have more details on the past issues so I can't tell if there is a systemic issue or not. I am definitely worried about this but I think time will tell. There was 40k miles between the previous issues and now. I hope I just got a flawed thermostat.
- The old coolant was very clean and clear. I don't think there was any leak stop stuff added but I can't tell for sure.
- I didn't see how the aux coolant pump could cause this issue. It is used to ensure a hot engine does not overheat after the engine is turned off since no coolant or air is moving. Unless the aux afterrun pump is required to assist the system to bleed... I never heard that pump kick on after I shut off the engine.
- Radiator fins are fine. It cools with no issues after the initial overheat. I ran it hard to try and intentionally overheat it and could not so I ruled out radiator and water pump.


My big lesson learned is that I should really do the correct coolant fill procedure if the cooling system is opened. Thanks all.

Siiboga.. I'll post some thoughts on your thread.

 

2012 touareg has a 10 year 100,000 mile powertrain warranty, unless you like pulling your hair out trying to diagnose and flushing money away bring it to a dealership.

Sent from my SM-G930T using Tapatalk

 

2012 touareg has a 10 year 100,000 mile powertrain warranty, unless you like pulling your hair out trying to diagnose and flushing money away bring it to a dealership.

This is 100% true unless your vehicle was totaled at some point,

OP Bring your car to the dealership, powertrain coverage is FREE

 

Had this issue on my '12 TDI Exec. Off we went on vacation only to get 50 miles away and my temp gauge starts going HOT.
1st the dealership thought it was a Thermostat sensor... they replaced. Week later starts again......this time its coolant pump.
They replaced (thank you Wrap warranty..lol)

Been good to go since!!!

 

The stupid thing overheated again this morning with cold air coming from the vents when it was too hot. Guess I'll get to use that coolant system refill tool after all...

 

Well I drained the coolant and used the vacuum tool to put the coolant back in and it still overheated. I took logs of the engine coolant temperature and oil temp. It looks like as soon as the coolant reaches 189 F (temp that the thermostat is supposed to open) the temperature immediately starts climbing quickly. I talked to a dealer tech and they said to always use OEM parts and that the water pump has some sort of shroud that helps the engine reach operating temperature quickly. There is a N545 valve that operates the shroud and it sounds like that might be the problem. I looked at parts diagrams and I cannot see any reference to this shroud or valve. It is possible that it is internal to the pump.

Also, I am able to log 2 Engine Coolant Termpatures with VCDS (ECT1/ECT2) but I cannot find a second coolant temperature sensor on this engine. I see the one at the rear of the engine on the driver's side but there is none on the radiator.

1) Can anyone validate the water pump shroud or N545 valve thing is real?
2) Can anyone confirm how may coolant temp sensors the T3 3.6L has and where the second one is?

 

As a general rule on VW, always OEM. Less frustration is always worth its weight in gold. Been there done that with many parts over the years.

The other sensor is on the radiator (per page 40 of the pdf I attached in previous post.)

The last aftermarket part I ever used was a starter in a 1988 16V. Install was a PITA, during last bolt tightening the protective shroud cracked exposing internals!!!! I never purchased an aftermarket part after this (exception being the Touareg center main bearing because that OE design is rubbish).

 

I looked at the PDF you attached (thank you) and see the 3 temp sensors listed but I do not see Coolant Temp Sensor G85 on my TReg and cannot find it in the parts diagrams at VW Parts website. I am thinking the T3 3.6L does not have a 2nd coolant temp sensor on the radiator.

Entire Cooling System (the one coolant temp sensor is not labeled but near #5:
https://parts.vw.com/a/Volkswagen_2...gen_2012_Touareg36LV6-Lux/_53892_6001587/MAIN-HOSES--LINES-COOLING/9241077.html

Waterpump (same temp sensor #15):
https://parts.vw.com/a/Volkswagen_2...wagen_2012_Touareg36LV6-Lux/_53892_6001426/MAIN-WATER-PUMP-COOLING/9241088.html

Radiator (no temp sensor):
https://parts.vw.com/a/Volkswagen_2..._2012_Touareg36LV6-Lux/_53892_5981255/RADIATOR--COMPONENTS-COOLING/9241075.html

Waterpump and Radiator (no temp sensor):
https://parts.vw.com/a/Volkswagen_2...Touareg36LV6-Lux/_53892_6387263/COOLING-SYSTEM-RADIATOR-WATER-PUMP/F50C040.html

 

*...see the 2 temp sensors..."

 

Seems missing. You might just call dealer parts guy...really common motor.

In the last link: It goes in #3 left (smaller component...lower radiator hose). You can even see the spot for it. Here is an actual picture of the joint between these two number three items (sorry for how filthy my engine is, my truck was built eleven years ago and has been offroading a bit and in snow often as well). The left one has the sensor in it.

Standing at front of truck, passenger's side, look down and it is directly in view (on mine unless something changed).

It is possibly this was done away with in later engine generations...but just seems unlikely.

 

Thanks for all your input. I have pulled the lower radiator hose twice and can guarantee that there is no sensor on the lower hose connection. I am not sure if the 2nd sensor has been deleted but at minimum it has been moved.

 

Interesting...and now we know!

 

There is a flow check valve in the coolant hose right off the cylinder head (above the cooling fans), it uses a plastic ball, sometimes the ball gets hammered into the plastic hole, remove and inspect.

Check vacuum supply to your water pump, the diaphragm should indefinitely hold a vacuum, also watch vacuum supply from the supply solenoid it should open producing a vacuum on cold start and then after a few minuets of run time turn off opening the shroud for coolant to flow.

 

I wish I could thank you in person, I replace both thermostat and water pump and spend about 700 USD on parts and labor but no effect. Plugged out the vacuum tube and WOW, it worked and no overheating.

 

Thank you very much for the vacuum tip. I still can't find the part on a diagram but should have enough to test with.

Yea.. I hate dealers. The nearest one is 45 mins away and I still hold a grudge about an alignment lie they told me on my past B5S4 (yes you can freaking adjust camber but it sucks to do it by moving the entire subframe). I have never owned a car new enough to have warranty and always wrench on my stuff. We bought this used also so I assume the warranty transfers. Bottom line is that I am stupid and haven't tried to figure out the warranty stuff. If I can't figure it out this weekend, I will go the warranty route.

Thanks for all the help.

 

Its no hassle adjusting caster on a B5 but there is only so much room to move the subframe, usually about .30-.40 degrees is max with a shift. If one side has 1.20 degrees more than the other there is something bent or worn out and no adjustment is going to get your cross caster in spec.

You should call VW customer care with your vin# and mileage and explain to them the car is overheating + you live 45 min away and are afraid the motor will be destroyed in the drive to the dealership, they should get you a free tow (and rental car)* VW customer care phone # 1 (800) 822-8987

You should never hate the dealership, if you had a bad experience it was due to a bad service advisor and/or technician and that's where your frustrations should be pointed.

 

Any news?

 

Yes.. I have been meaning to come post the resolution.

After I pulled the vacuum line off the water pump we had no overheat events for over a week (16+ drive cycles). I considered this confirmation that the overheat issue was from the waterpump shroud staying out too long. I still didn't know if it was an issue with the solenoid that controls when vacuum is applied or if the shroud mechanism in the waterpump was at fault. The solenoid is SUPER easy to replace. Normally, new OEM solenoid is $70 but I found a new one on ebay for $20 so I ordered it (this solenoid is used on a bunch of other vehicles so fairly easy to find a used one). I put the new solenoid on and we have had no overheat issues for about 2 weeks (28+ drive cycles). I typically don't like troubleshooting by replacing items but $20 with 15 mins labor was a no brainer.

NOTE: The part number of the solenoid is 037 906 283 C. The VW parts website does NOT show that this is applicable to my T3. I cannot find this solenoid on any of their parts diagram either.

Thanks for all the help!

 

SaaaWeet! Glad I found this... Just driving along and then my Temp jumps up to 220, then 240... hangs out a bit then drops down to 200.. then goes back up , then down. Then days go by with no issues then its back...

Ordered up the part today from Ebay for $50 rather than $90 from 1stvwparts.com. I will advise once I get it installed and drive a few cycles.

 

Thank you for information. Can you please send me picture of that solenoid on your engine?

 

I took a swing at the pictures.

Pics:

 

I took a swing at the pictures.

Pics:

Mind reposting the pics?? Having the same problem and the pics are showing not able to load.

 

Syxxty.. You are the man. I was having the same problem. The car tried to over heat once on the expressway. Took it in and had thermostat and coolant flushed. After that, every time I drove the car, it would try to overheat. I thought it had to be an air pocket. I was arguing with tech as he said it had to be a bad water pump. I didn't have any leaks and it was too sporadic to be a pump. When I pulled over, eventually the car would cool down in a mater of seconds.
I pulled the vacuum line and plugged it. I have driven both local and expressway for the last week without even a hint of it trying to overheat. I will have to order the sensor/vacuum to do it right. But this was an awesome find. We were getting ready to trade it in since this is the car my wife uses with the kids and we need it to be reliable. The recommended water pump and timing belt was not an affordable option for us right now.
MANY THANKS... If you were local, I would bring you a case of beer.

 

Disconnecting the line from the water pump and the overheating has stopped!

 

My Touareg is having this same issue can someone please explain in stupid terms where/what the vacuum tube is so I can unplug it.

 

its a tube right behind water pump pulley connecting vacuum solenoid and water pump

 

3-Thermostat, New Water Pump and New coolant system

My 2012- Touareg is again in the shop - engine light referring again to themostat. Wow... Number 4 this will be. I only have 53K on it. I also have replaced the water pump and coolant system. Just wished they would find the problem. VW -service is bringing in a Engineer to look. Seems with 4 times a charm- could be a lemon case. Sara

 

Yes.. that sounded like the one. Its annoying that it was something so small.