[Quago]

Hello! New day another problem with this car.
Noticed this yesterday while towing my boat, I could see the gauge go from 90 down to 70 when slowing down to take a turn, then dropped even more while accelerating after the turn.
Engine coolant temp read 68-73c 73 being 90 at gauge and 68 being 68 at gauge
Oil temp 83-85c
It does not behave like this while driving in town where the temps are good.
Im looking for someone who had this problem and can tell me what it was before throwing parts on it.

Edit: it reaches 85c then starts rapidly dropping to 70 to pretty much stay there. Hm open thermostat?

 

[Quago]

The Touareg's temperature gauge is artificially managed - if you use VCDS or Scangauge plugged in to the OBD port and read the actual sensor values they can be very different - during the warm-up phase the gauge will show 90 when the sensor has only reached 60-70 - so you can't rely on the gauge for diagnostic purposes.

Your fault could be faulty thermostat or faulty gauge - but you need to know the actual sensor values to do the diagnosis.

I checked obdeleven, the gauge called 'Engine coolant temp'. I monitored this from cold start, the gauge in the car shows 90 when that shows 70.
The obdeleven gauge climbed to 85c then rapidly dropped to around 70 and it never raised above 73 after that.

 

[Quago]

What engine are you talking about? You could have 2 or 3 CTS. Need to look at multiple things to isolate the problem or failed component.

The CRCA engine

 

[Quago]

Thermostats.

Thank you.

 

[Quago]

I have to look it up, but that sounds like the 2nd gen, so similar to our CNRBs, meaning that you'll have 3. Monitor all 3 plus the oil temp and rad fan to see what it reveals. Has the coolant system been correctly filled and bled?

I have had this car since december and done like 4000km, ive not even opened the coolant reservoir and the level is the same, ill check all the cts tomorrow omw to work.

 

[Quago]

Update: i drove the car hard this morning while monitoring the temps and they all looked good... 92-98c engine outlet coolant temp
Oil temp 90-101 depending on the driving
Then just cruised for a while. The problem seems to have disappeared for now 🤔

 

[Quago]

The crca engine right?

Yes

 

[Quago]

Well done on not doing anything that was suggested.

Thank you, but I did, I could not see anything off?

 

[Quago]

Okay now everything is off again, this is the stuff i can read with obdeleven

 

[Quago]

I repeat.....

Ideally, you should be logging the data, since you can't spot anything, and you're not showing us anything....
Also, whatever limitations ODBeleven has are irrelevant to the troubleshooting... either figure out how to do it with what you have, or get what you need... or start throwing parts at it.

The only thing i can see is that the thermostat opens at 70c, coolant temp.

The only way to get it to dont do this is to drive the car hard to get The engine oil to 85+c then everything to work as normal. This seems like a sensor problem to me? Im sorry i dont got the right stuff to monitor this.. obdeleven is what i have at the moment.

 

[Quago]

Thermostats.

I have one in the oil filter housing and one next to the waterpump, correct?

 

[Quago]

You're not getting it.
Unless you're able to look at\monitor all the sensors your engine has, you're not isolating the problem.
Do you understand that your have 3 CTS?
Have you looked at 3 different CTS to compare what they are reading, and to use that information in conjunction with what the rad fan is doing, and what the oil temp is?

I can only find 2 CTS in obdeleven and i have monitored those. From that i can tell the radiator outlet is way cooler then the "coolant temp" sensor.
But thats about it.. Engine oil 74-80c while driving calmly
Coolant temp 67-72
Radiator outlet about 30-40c

 

[Quago]

What you can find doesn't matter.
If you don't know what you're looking at, there's no point in looking at it.
Ofcourse the RAD outlet will be way cooler than whichever other CTS you're looking at..... you could be looking at the one in the EGR cooler inlet, or the one in the block.... both will be hotter.
If your oil temps are only 80ºC, you're not even fully warmed up.

Thank you. I guess that is the problem. Car never warms up, I didnt have this problem a month ago at -15c now its +7 outside and car cant get up to temp.
Usually takes 10 min tops at these temps. Drove for an hour today in town only getting to 82 oil temp.
The other CTS is called engine outlet.

 

[Quago]

Have you read the SSP applicable to your engine?
If your oil temp is that low, I'd almost suspect your oil thermostat being stuck open.... the block oil temp should be regulated to something ~103ºC.... the coolant system ~105º, the coolant bypass valve ~90ºC, etc..... you need to understand all this when attempting to troubleshoot so you can evaluate the readings from the various sensors and the rest of things in order to isolate the issue.

So the oil temp cant be low because a open coolant thermostat?

 

[Quago]

Does anyone see anything wrong here?

 

[Quago]

Probably, depends on your engine code. You need to change both of them, for peace of mind. BTW, you need to change the whole filter housing, so i've heard.
I have a CASA engine code and mine is not in the oil filter housing, its on the EGR cooler and it was the culprit (yours should be the one in the filter housing).
Before i changed them, i made a log to be sure:
View attachment 269820

What in this log is the fault? Im learning by all this of now.

 

[Quago]

The coolant coming out of your block is way colder than the oil circulating in the same bock.... this doesn't compute!

Yes! I was just out for a drive... coolant temp reached 80c normally until oil temp hit 70c then coolant temp rapidly decreased to 66c.
Then it took about 20 minutes for the oil temp to reach 80c. Another 15 minutes for 84c.

If you had to guess what would be the culprit here?

 

[Quago]

Test like this, start engine and drive slowly untill temp is over 70-80 then accelerate and drive faster and if the temp drops my bet is your thermostat is stuck open.

In my graph, where you see spikes in temp is where i wait at the red light (no air cooling the radiator/coolant), then, when temp drops it means i accelerate (air hitting the radiator)..and so on.
Thing is, cooling system on this model is not that simple, there is a main one, secondary one...

It also helps to read the service manuals to understand better, i think @SaVAGeSoot made a topic with all the manuals.

Thank you, it does exactly this.
But it also lowers coolant temp for a sec while coasting for a turn etc.
Then drops while accelerating at first then rises until i drive normal then it drops again.
Ive ordered oem thermostats and 2 sensors now. Hope this will work!
I really need to get vcds if im gonna keep driving vag cars 🤔

 

[Quago]

Open this screw and check if air is comming out. If there's only coolant its ok.

Will do! Can car be turned off?

 

[Quago]

Today i had a massive coolant leak i love this car