(Continued)

About 250km into the trip I noticed the temp gauge going above 90 degrees C, something I've never seen before, and I've done a fair bit of towing on this same highway (the North Shore of Lake Superior which has some decent climbs) It would go as high as 105 on steep/long climbs but once I noticed it I started to ease up a bit and try to keep the temp in check. And no point did I notice a lack of heat and the vehicle was it's usual quick warming up self.

I was pretty limited on what I could do while away, although I did bring coolant with me and tried to burp the system by squeezing the hoses etc.

I'd read on this forum and many others that the temp gauge is "stuck" at 90 unless there is something drastically wrong, so I dug out my OBDeleven dongle and went through the painful process of getting connected to the engine control module so I could view live data, and also researched the temperature senders (all 3) and the oil temp sender for verification.

I was able to more or less verify the proper operation of all the sensors and they pretty much agreed with each other when cold in the morning.

Once running and warmed I would see the main temp sensor at about 88-92 degrees C, like you would expect, the rad outlet slightly above ambient (a few degrees below freezing) and the "temperature sensor for engine management" would strangely be at 110 C or so, going higher if I drove too fast (108km in heavy snow and slush) or climbed any appreciable hills.

I learned that a temp reading higher than 118 deg C or so would cause the temp gauge to go above 90, and generally I could keep the temp under 122 or 123 and the guage might go as high as 100 or slightly above.

By the end of the week I had spent numerous hours googling and researching the cooling system, reading the factory manual and study guides, etc. trying to understand the system. By the time I got home I was convinced it was either a bad sender, or a faulty coolant shutoff valve, or maybe a faulty solenoid for said valve.

I spent some time in my workshop today trying to get to the bottom of it, trying to run an output test on the valve, isolating and disconnecting it, etc. and I think, but am not %100 sure, is the new valve is possibly sticking closed. Of course it's IMPOSSBLE to observe it.

I did at one point go for a good length drive after disconnecting the vacuum to the valve, and it seemed to be opened (which is it's default), and I finally got the two temperature senders to agree with eachother, they were both at 95 degrees. I reconnected it, turned around, and it started to heat up again. I then disconnected it again, and it CONTINUED to overheat.

I see from normal scans that I found on this forum, you'd normally expect the sensor for engine management run in the 100 to 105 range with the other one at normal thermostat temp of 90-ish.

In my quest to actually figure out the valve operation, I stuck my inspection camera everywhere I could looking for a view of that damn valve. Curse the engineers for sticking that this down there with abcolutely ZERO feedback. There is simply NO WAY to verify it's position. But I digress.

What I did find, is liquid. Quite a bit of it. A mix of coolant and oil from what I can tell. I didn't lose much oil over the week, maybe 2-300ml over 600km or so, not unusual at 200,000km IMO.

I was "burping" the system and thinking maybe I made some progress but I guess I have and answer to that, now.

So here I am. Very frustrated and tired. Not going to lie, 1200km of driving through the winter weather we have to deal with on snow covered two lane roads with one eye looking for moose and the other one on the temperature gauge does not make for a relaxing drive!

So, I'm at a loss. Why the overheating? How can I be sure? Where in gods name is the leak coming from? How can I see 125 degree temps and not get a warning? Or throw a code for "temperature control problem" or something?

At this point I'm deathly afraid that I've blown a head gasket and if that's the case I don't have the equipment or space to do an engine-out job. There simply isn't a shop I can trust to do that around here so that would be a predicament I don't even want to contemplate, especially after all the money I just spent on this thing.

OK, so a bit of a lengthy rant, here. But I feel the back story is important and I needed to get this typed out. At this point I've got a million things swarming around in my head, like front cover seals, etc. s#&^$tty aftermarket valve that's sticking maybe? Is it leaking too?

Anyone else face similar issues?

Thanks in advance, Jon in Thunder Bay.

 

If you can I would try removing the tune and see if you still have the overheating issue with the standard ECM software. You also need to find the source of the oil / coolant leak though if the coolant system is still full its unlikely to be the over heating cause. Do an coolant test for exhaust gases in the coolant to determine if you have a leaking head gasket

 

Did you pressure test the system for any leaks?

 

If you can I would try removing the tune and see if you still have the overheating issue with the standard ECM software. You also need to find the source of the oil / coolant leak though if the coolant system is still full its unlikely to be the over heating cause. Do an coolant test for exhaust gases in the coolant to determine if you have a leaking head gasket

That's a good suggestion, I was planning to do that today. You're correct it's not losing coolant at a very fast rate but can't help but wonder if it's getting worse. Yesterday I saw steam and smelled coolant which I did not observe all week, but on the other hand it was a rainy mess yesterday.

Is there a known reliable accurate test available? I'm not familiar with them. Cooling system does not seem to be pressurized, no white smoke, oil not cloudy, etc. so I am optimistic about it. But still scared!

Did you pressure test the system for any leaks?

I did a vac test when I did the fill, but my tester only does vac not pressure - it's a universal rubber cone type. So I might bit the bullet and get one with a proper adapter and a pressure pump.

I'm thinking I need to get the manifold off to gain at least a modicum of access and visibility for the location of the leak.

Thanks for the suggestions, I'm still pretty early in the troubleshooting process, I admit.

All the best, Jon

 

Get a laser temp gun to help you validate what sensors are telling you.
I've had funky temp gauge readings when my Engine Management Coolant sensor failed.
I'll try to dig up my charts\scans to give you things to look at and\or compare, but it was all VCDS and not ODBeleven junk.

Can you log\chart with whatever diagnostic tools you have? I suggest doing that as it's much easier to see what's not behaving when looking at a chaart.

 

Jon,
Have a look at this thread.... you may have already seen it, but some of us were trying to sort our some ECT issues, and if you go through all of it, it has a lot if not most of the data\references that I would point you to.
2013 v6 tdi engine temperature question.

That drive is quite demanding, I've only been up to Kenora from my neck of the woods when the roads are clear, but I can totally imagine how it would be in wintery conditions.... gorgeous scenery, but probably not where you want to be with a malfunctioning vehicle. (especially between TB and Dryden, out in da stix)

 

I did see that thread (THANK YOU!!!!), it was very useful, it may be the one where it was made clear to me to check and monitor 4 temp sensors at once! I'm a controls technologist so my life pretty much revolves around sensors and data, and correlations to determine faults. I can't believe VW put a coolant shutoff valve buried in the most inaccessible innards of the "V"....

 

SaVAG, you'll have to forgive my lack of forum etiquette as I somehow can't figure out how to quote in a reply at this moment and since I'm in the workshop sitting on a 5 gallon pail typing on my laptop and using a tethered hotspot off my phone I'm a little reply-challenged!

I did, just now, verify with a handheld gun that all 3 temp sensors are reporting measurements that are within a few degrees of reality. I did previously double check all 3 plus engine oil temp to more or less agree with ambient after sitting for 14 hours or so. But the infrared gun settles the remaining question of their accuracy when hot, and also oil temperature at that time was very close to the "temp sensor for engine management" in OBD11-speak, "engine temperature control sensor" (G694) in VW speak.

I believe I may have cracked the issue with the overheating - but still unsure how to further verify the theory. I understand the need for proper logs and charts, but to date haven't dug into OBD11 to conquer that functionality although it appears to be there all I get is:

If I had a dollar for every time I sat like an idiot staring at that stupid swirling circle in OBD11, I could buy a pro unlimited deluxe gold plated version of VCDS!

(con't next)

 

The limitations of OBD11 notwithstanding, at the time I purchased it VCDS didn't seem to have a mobile version or a wireless dongle (that I was aware of at least). I'm seriously considering upgrading to the new wireless dongle with laptop and mobile functionality. It's a chunk of change and I feel like I'm headed for further strain on my budget!

I did grab a few screenshots during the long drive home friday afternoon that perfectly illustrate the typical values of four critical temp sensors.

First one, a normal low-load, cruise situation. Temp gauge pointing straight up the middle at 90 deg C. (194 f):

The "temperature for engine management" was always at 15 or 20 deg greater than the other coolant sensor and oil temperature once warmed up, at this point I'd been driving for a few hours.

Now, going up a big hill. THIS is where the ALARMS!!!!! start going off (well, in my own head at least) and the temp gauge would creep up to 105 or so. This was the single highest temp I observed all week over several hundred KM of monitoring. The temp gauge movement was the only thing alerting me to this and it would very quickly drop to 90/normal. Although it may as well have a happy face in the middle and $$$ signs on either side of it!

Fast forward (as long as you aren't going up a hill) to today, and I logged over 100km trying to get the engine to overheat with the coolant bypass disconnected. It has been completely isolated from vacuum since yesterday and I am pretty sure it is in it's opened, default position at present.

As a double check of the temps I monitored during warm-up and all looks right in the world:

And this, the hottest I was able to get things, even hammering up some hills at speeds high enough to get me in the Stunt Driving Hall Of Fame (it's an inside joke for those in Ontario):

This would seem close to ideal for me, although I do know from the factory description of the CNRB the block temp is supposed to be somewhat higher, and the average temp of the G694 sensor should be in the 100 to 105 range.

My highjinx actually, finally, resulted in a fault code (but no MIL) at least it makes sense since I did have a major part of the engineers dream disconnected...

That's all I've got for now!

 

Ok... So once again, I'll attempt to suggest things, but understand that I'm telling you do to things that I'm able to do with VCDS, not the Mickey mouse diagnostic you're using.

Time to run output tests to confirm functionality of critical components.

So the most obvious would be the rad fan... Make sure (or even better), monitor it's duty cycle when you are seeing temp gauge action.

The other one I'd run would be the one for the valve actuator solenoid that you've disconnected. Make sure that it actually makes the valve do something when the ECU commands it to.

Lastly (and I'm gonna get a lot of heat for this), since you're tuned and it only happens under load, watch your EGTs, IATs and AFR. I'm willing to bet your tuna is dumping fuel and driving all those through the roof under that load and actually causing the overheat in an otherwise normal running system.

 

Ok... So once again, I'll attempt to suggest things, but understand that I'm telling you do to things that I'm able to do with VCDS, not the Mickey mouse diagnostic you're using.

Time to run output tests to confirm functionality of critical components.

So the most obvious would be the rad fan... Make sure (or even better), monitor it's duty cycle when you are seeing temp gauge action.

The other one I'd run would be the one for the valve actuator solenoid that you've disconnected. Make sure that it actually makes the valve do something when the ECU commands it to.

Lastly (and I'm gonna get a lot of heat for this), since you're tuned and it only happens under load, watch your EGTs, IATs and AFR. I'm willing to bet your tuna is dumping fuel and driving all those through the roof under that load and actually causing the overheat in an otherwise normal running system.

All good suggestions - and as Mickey mouse as it is, I'm not going to blame my tools, I'm stuck with OBDeleven for now, but I am able to do everything I've needed so far, including:

- rad fan output test - indeed, it functions, and at 100% it sure makes a racket! At the ambient temps I'm seeing I wouldn't expect it to run (or be needed) to cool anything, as the thermostat alone seems able to provide enough cooling. I've seen rad outlet temps go no higher than 15 degrees, usually much closer to ambient especially when it's well below freezing. I'm ASSuming the fan satisfies demand for cooling based on engine coolant sensor G62?

I suspected failure of the solenoid for the coolant shutoff valve at first, since I did read of a failure on this forum I think(?). I plugged the old valve I removed into and performed a function test on it and it worked perfectly. So no issues with ECU, vacuum, solenoid...

But here is where it gets interesting. I am 99% sure the valve currently installed in the vehicle is stuck CLOSED. If I blow into the line going to it, I can feel movement of air back and forth, and I can hear the diaphram in the valve working back and forth. Of course if I try to move the old one by connecting a line and blowing into it, it barely budges. But if I hold it closed, and do the same blow test, I have exactly the same amount of air moving back and forth in the line and it makes exactly the same noise.

If I wait long enough for things to cool down, the valve eventually unsticks itself and opens. My 100km test this morning was from cold, with the valve disconnected, so it never had a chance to stick closed.

I then reconnected it and boom! back to the high temps. And even when I disconnected it, the temps won't go down, and my "sound test" proves it's stuck closed.

I'm really, really, really mad at myself for installing that valve. I got it as part of a kit from tdiupgrades.com that included an oil cooler, intake gaskets, the plastic flange, and the shutoff valve. The cooler was supposed to be Nissens brand (it was), and the two plastic parts were supposed to be Febi. They did not come in any identifying packaging or have any identifying marks. So for all I know its some URO garbage that they substituted.

I don't have anything against using aftermarket parts from an OEM supplier like Febi, or Vaico, etc., but draw the line at the no-name garbage from Amazon. And I shouldn't have accepted and questionable supply for such a critical part. I have a new appreciation for how critical... and how difficult to diagnose.

I appreciate the concern about the tune - It just a stage 1, +10% and very mild, but I re-loaded the stock tune in and there is no difference in the temperatures in the cooling system or behavior of the gauge. Not saying that the tune couldn't have pushed my marginalized cooling system past it's break point when compared to stock - any tune is taking advantage of some engineered-in additional capacity and over engineering but there's always a compromise of some sort.

So... that leaves me fairly convinced that the valve is the cause of the cooling system issues and gauge fluctuation, but it doesn't solve my continuing leak. I don't have time to type any more ATM, but curious - what is the likelyhood of EGR cooler leakage on a CNRB? And how does it present itself? I researched it and thought it to be unlikely, at least when compared to the earlier versions of the V6?

I did what I could today with the inspection camera, and don't think the front cover or that plastic housing bolted to the back of it is leaking, but there does seem to be coolant on top of the oil cooler adapter plate at the back of the oil cooler.

I'd like to think maybe it's the damn coolant valve leaking but the liquid I pulled out is coolant, but it's turned blackish and has a faint combustion smell to it like the EGR components. Also there is an oily paste above the high level mark in the cooling reservoir.

That last paragraph has pretty much ruined my day... can I be optimistic at all that it might not be a head gasket? I need a drink.

Cheers. Jon

 

Unlikely to be HG. More than likely oil cooler seals. Time to pressure test the coolant system.... Probably while running output tests on both coolant and EGR bypass valves.

Also unlikely (but possible) that your EGR cooler is leaky, so you could always monitor EGR bypass valve to see if it's status coincides with your overheating activity. I'd also monitor the rad fan and coolant thermostat to see if they are stepping in when overheating happe a to try to control temps.

 

I did do one final test tonight - let the vehicle cool down while I ate supper, during which time it cooled off to 50ish degrees and the valve unstuck itself during that time. I double checked it with the suck/blow test to confirm it was indeed returned to it's default open position.

Drove for a bit with the vacuum line to the valve disconnected and both coolant senders and the oil temp stayed within a few degrees of eachother. It does warm up a lot quicker with the coolant shutoff CLOSED... but it sucks that it keeps heating up when it malfunctions and sticks in the closed position... I'm fully convinced this is the cause of the slight overheating and the temperature gauge fluctuations above midpoint.

I have no doubt that the thermostat is working, as the coolant sensor G62 rarely goes above 92-93 before I see an bump in rad outlet temp, indicating there's some flow through the rad. I don't think anything is getting hot enough to trigger the cooling fan but it's something to look at I suppose.

I did also do a vacuum check on the cooling system tonight, and it's solid - 30-40 minutes at -20 in. hg and no loss. Mind you one bar positive is a different story. I ordered a pressure test kit.

Thanks for all the advice!!! I'll keep updating as I have time to work on it. At least getting that damn manifold off will be a lot easier since I took the engine hoist hook off front corner of the 1-3 cylinder head, and I know to disconnect the high pressure lines at the back of the rails, too! I also got a fancy socket so I can remove the HP rail sensor without damaging it, and things always go faster and easier when you've done them once, and everything is clean.

 

I've ordered the coolant shutoff valve from the local dealer but have no idea what's causing the leak. Best case scenario is the one part solves both problems! The pressure test is going to be pointless unless I can do it with the manifold removed, so that'll have to wait till the weekend.

Will be sure to keep the thread updated and report my findings.

Thanks, all!

 

The pressure test is going to be pointless unless I can do it with the manifold removed

How so? If you're suspecting the EGR cooler is leaky, wouldn't you see coolant make its way into the EGR pipe going to your intake horn?

 

I was contemplating what the interactions of coolant and exhaust could be in various scenarios of EGR failure and it suddenly occurred to me that boost pressure could actually exceed that in the cooling system... yowsers.

 

I'm getting coolant in the valley so my comment was based on not being able to see much

My suggestion was based on your earlier mention of

what is the likelyhood of EGR cooler leakage on a CNRB? And how does it present itself?

 

Localizing leaks to EGR cooler:
If your leak is at the coolant supply flange, you'll get coolant in the valley (no oil... just coolant)
If your actual cooler is leaky, you'll have vanishing coolant which you'll be burning and you should be able to see evidence of this in the pipe going to the intake horn.

 

I read this about another possible EGR cooler leak mode which seems like it might better explain the oily gross burnt smelling mess in the valley:


"When they clog up, they DO start to leak... oil. Because the EGR tube that drops from the intermediate intake pipe now starts to collect oil from the breather system that would normally just blow through... and it collects in that tube, all the way down to the cooler itself, and because that is all under boost pressure, it eventually starts to shawshank its way through anywhere it can, which includes the vacuum servo on top of the EGR cooler itself, and starts making this huge oily mess everywhere.

Awful messy job. Done a bunch of them, and there is going to be a bunch more as all these come out of warranty."

Courtesy of user "oilhammer" on tdiclubforum.

 

If it all seems to hard to deal with, just be like me and top off with coolant once a month😂

 

EGR delete is a four hour job, give or take.

 

I just noticed in your signature that your car is tuned with 300k km on it, I know it’s unrelated to this topic but is that on the original turbo? I want to tune mine but I’m worried of blowing the turbo with 284k km on mine and I hear a slight whining occasionally

Original turbo from what I can tell but no issues so far -- unless the persistent slight coolant loss is coming from the turbo. It used to be every 6-8 weeks prior to delete, now it's once or twice a year. If your turbo has preexisting issues, more boost will only exacerbate anything that's already there.

You are a brave man!

Que?

 

Que?

What's the purpose? Are you somehow putting a load onto it and I'm missing it?

 

I'm saying you're just reving up a cold engine, without any load on it .... Maybe I'm missing something

 

'twas -23 deg C here yesterday and I watched the actual temps of the coolant temperature and oil temp as I did a bit of running around. Never during an hour of running errands did any of those temps go above 60 degrees C. Of course the gauge read almost 90 the whole time.

The Treg doesn't run quite right when it's not up to temp. Everything feels a bit off, especially the transmission.

This was with the EGR functional, but the coolant shutoff disabled and defaulted to fully open.

Looking forward to getting everything back up to snuff.

 

Just following up and closing out this thread. Happy to report the humpty touraeg as all back together. Lesson learned (for what must be the 100th time) don't use anything other than factory parts, or ones that are at least made by the same supplier as factory.

The issue I was having was the (crappy aftermarket) coolant shutoff valve, sticking CLOSED under high temperature. This valve was sold to me by TDIupgrades.com as being a Febi brand valve, but I know Febi to be a high quality German brand. The valve I received from tdiupgrades.com did NOT come in Febi packaging or have any identifying marks. I (stupidly) took a chance and changed out a perfectly good factory valve for a faulty aftermarket one and ended up having to lop the manifold off for a second time.

I'd been detecting a slight note of diesel exhaust from time to time so figured maybe re-using the gaskets on the various EGR connections wasn't the hot setup so I changed a few other things while I was at it.

My local VW dealer hooked me up with parts prices the were as good as or better than any of the online sources, and got me stuff in a matter of 2 or 3 business days from Toronto (the centre of the Canadian universe).

The second manifoldectomy was a lot quicker than the first, and I managed to replace all those parts and refill the cooling system in 4 or 5 hours of leisurely work.

The result is no more overheating, no more leaking! Got a good shakedown run in this morning, check out that outside temperature! Temps got up there nice and fast and stayed rock solid for 130km of highway driving including some decent sized hills and some lead-footed behavior on my part.

I'm not completely out of the woods yet, as having put a couple thousand km on the vehicle that the front cover is weeping a bit so that job needs to be done too. I simply couldn't tell as there was such a mess under the hood I had to start somewhere. Looks like it's very slight, and very well may turn out not to be worth the effort, time will tell.

Last but not least, I loaded the Malone Stage 1 tune back in and wow!!! It's so nice to have that back. The combination of the stage one and their TCU tune is just fantastic. Nothing outlandish, it just makes the Touareg everything it should have been from the beginning. I'll post a separate review to the forum as a service to this community when I have a chance.

Thanks all for the advice and support through this, it means a lot to me! I don't "hang out" here too often as I spend most of my time on the Pelican Parts Technical forum, but I'll make it a point to drop by a little more often. I think these CNRB powered vehicles are going to become more and more popular with the DIY crowd and I for one am a lot less mystified (and scared) to dig in and fix it when it needs it. I hope to keep driving it for a long, long, time!

Thanks again and cheers! Jon

 

Good to hear you got it sorted.
A few on here have found out (the hard way as well) to go with OEM/OEM supplier parts.

 

While I agree with OEM parts being good generally, in some cases aftermarket parts can be better quality (example can be OEM components being plastic VS metal aftermarket), but with some parts the prices are much more.

For example, when I replaced my air suspension compressor an OEM Continental unit was $1,200 vs an aftermarket for $400, which for an aging and heavily depreciating car isn’t worth putting so much money into. At least with Japanese cars they hold their value so it makes sense but the stigma with Euro cars (at least in Aus) makes them essentially worthless compared to sub par Japanese counterparts.

To be fair, the aftermarket compressor is a bit noisy but considering it’s 3x cheaper that doesn’t bother me