Engine fan running a lot

ThomasCo

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2010 JSW TDI
Hi everyone,

Vehicle is a 2010 JSW TDI (CJAA). I noticed recently after doing an oil change and DSG flush (but also intermittently before) that my engine fan is running a lot on high speed. I noticed that while driving, specifically when making a stop at a red light, that the engine fan runs a lot and at high speed. When I turn off the engine the engine fan usually keeps running for a few seconds, not nearly long enough for it to be a regen symptom (also the idle rpms don't suggest that). This happens pretty much every time I drive it, usually after shorter trips but also after longer and faster ones. My AC hasn't been on in weeks, temperatures in the 50s-70s here in CO.

The coolant temperature gauge in the instrument cluster sticks at 190 or below, it never goes above 190. It does take awhile to get there though, especially when it's colder out, and when at 190 and going downhill for a mile or so with little to no throttle, the gauge drops slowly, which would be consistent with TDI behavior and does not make me think I'm dealing with a faulty CTS here. I also hooked up my VCDS after a 20ish mile drive yesterday and went into the engine module and the coolant temperature was at 83C -- the engine had been off for less than a minute at that point.

I tried the AC troubleshoot for the fans - turned on ignition, set fan to 1 and turned on the AC. Light comes on, fan is running but neither one of the two fans in the engine bay turns on. VCDS output test for coolant fans seems to be working properly though, both fans turn on when running the test and go back and forth between low and high speeds until test is stopped.

Lastly, requested regens in VCDS shows 2.0 (was 5.0 on the weekend), completed 0.0, mileage / consumption and time since last regen all blank.

Could it really be that my vehicle is running regens this often and for some reason they never finish? Or am I looking at a faulty AC-related switch here? The AC does work though!

Apologies for the novel, planning a road trip for next week and don't want to just ignore this.

Thank you so much guys!
 

JELLOWSUBMARINE

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How long and often are your active regens? Its pretty hard to tell unless your hooked into a VCDS or other type gauges. The upcoming long drive would be good input. It sure sure seems it could be DPF/regen related. Possible bad/filled DPF?
 

ThomasCo

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2010 JSW TDI
How long and often are your active regens? Its pretty hard to tell unless your hooked into a VCDS or other type gauges. The upcoming long drive would be good input. It sure sure seems it could be DPF/regen related. Possible bad/filled DPF?
The only active regen I’ve witnessed thus far since buying the vehicle was for approx. 15 minutes or so during a 30 minute freeway drive. I only noticed it by the lower than usual fuel economy and the fact that the fan stayed on for approx. 5 minutes after shutting off the engine. On the way back everything seemed normal. I’ve only owned the vehicle for about 4,000 miles, of which 2,500 were a 3 day road trip.

Oil ash volume is at 198 ml / 187,000 miles, although I read that’s not necessarily an indicator for anything. Soot level calculated at 6,3g, measured at 0,0.
I should also mention that the vehicle passed Diesel emissions with no problems when I bought it. The DPF light has never come on and there’s no indication of soot on the tailpipes. Also no fault codes whatsoever upon Auto Scan.
 

JELLOWSUBMARINE

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This is my first DPF (but 4th VW diesel). It took the Polar FIS unit for me to really understand and treat the active regens properly. That along with a non delete tune, and this DPF is on track for a long healthy life. Maybe it's just me but I highly recommend some sort of monitoring. It really sounds like your car is in good health but quite possibly not finishing the regens or a filled DPF? Do you smell anything when the high fan speed after shut down?

The calculated soot level is VWs programming of what they "calculate" it presently is at. It ranges from 0.0 to 24.5. @ 25.5 the active regen is triggered (other parameters must be present also). The calculated numbers, for my car, isn't even close to actual soot load (usually 5xs less). 187k is alot of miles. Is that the original DPF?
 

ThomasCo

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2010 JSW TDI
This is my first DPF (but 4th VW diesel). It took the Polar FIS unit for me to really understand and treat the active regens properly. That along with a non delete tune, and this DPF is on track for a long healthy life. Maybe it's just me but I highly recommend some sort of monitoring. It really sounds like your car is in good health but quite possibly not finishing the regens or a filled DPF? Do you smell anything when the high fan speed after shut down?

The calculated soot level is VWs programming of what they "calculate" it presently is at. It ranges from 0.0 to 24.5. @ 25.5 the active regen is triggered (other parameters must be present also). The calculated numbers, for my car, isn't even close to actual soot load (usually 5xs less). 187k is alot of miles. Is that the original DPF?
I don’t think so, like I said, I bought the car used some 4,000 miles ago but it only has the emissions fix done 2 or so years ago, the extended warranty is still good for another 10K miles. Wasn’t DPF replacement part of the emissions fix?
 

Wilkins

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05 Jetta Wagon 5sp, 10 Sportwagen 6MT
If your soot level is 6.3 it suggests a regen happened quite recently. The counter starts at about 2 and goes up to 7 at which point it regens Running on the highway I doubt you would notice a regen taking place. It’s only when a regen is interrupted that the fans run on after the car is shut off. Happens occasionally. I don’t think you have any problem with the DPF.
Pretty sure what you do have is a failing thermostat, just like my 2010. After about 10 years they are about done in any car. The temperature gauge is digitally controlled and shows 190 If the coolant is anywhere between 75 and 100 C so 167 and 212 F. If the gauge drops going down hill with the ambient well above freezing that thermostat is done! Until I put my IDParts winter front on mine wouldn’t hold 80 C on the highway(supposed to be 90) but the gauge wouldn’t drop on a long downhill. With the front on it will run up to 95 on a slight hill, which it didn’t use to, so I think my thermostat isn’t working properly. Bet yours is about the same, the rad fan is running because the coolant is hotter than it should be when the engine is shut off.
 

JELLOWSUBMARINE

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I don’t think so, like I said, I bought the car used some 4,000 miles ago but it only has the emissions fix done 2 or so years ago, the extended warranty is still good for another 10K miles. Wasn’t DPF replacement part of the emissions fix?
The first post you say the car is a 2010 CJAA. Im quite possibly wrong but I thought the CJAA was introduced in 2011 on mk6?... Nevertheless, the emissions warranty is for xxx miles OR 10 years from in service date. My 2011 for example will time out 6/21. Hopefully your within the 10 years. Id call the dealer and at least confirm your status.

Ive heard of cars not getting DPFs on the fix.

If your soot level is 6.3 it suggests a regen happened quite recently. The counter starts at about 2 and goes up to 7 at which point it regens
Are you using the Polar or VCDS when referring to the (2 up to 7)? Im not familiar with the VCDS.

Pretty sure what you do have is a failing thermostat, just like my 2010. If the gauge drops going down hill with the ambient well above freezing that thermostat is done!
Thats seems like a great check.
 

ThomasCo

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2010 JSW TDI
The first post you say the car is a 2010 CJAA. Im quite possibly wrong but I thought the CJAA was introduced in 2011 on mk6?... Nevertheless, the emissions warranty is for xxx miles OR 10 years from in service date. My 2011 for example will time out 6/21. Hopefully your within the 10 years. Id call the dealer and at least confirm your status.

Ive heard of cars not getting DPFs on the fix.
It‘s definitely a CJAA, engine code CJA all over VCDS and on the sticker in the trunk. I ran my VIN through the Dieselgate checker on VW.COM, and it says I’m good to go until 12/2021 or 194,000 miles (4 years/48,000 since the fix). So I’m still under warranty.

As for the thermostat theory, how would I go about testing it? The heat works reliably in colder weather, even when not cranked up all the way and without auxiliary heater kicking in. I did read that it’s normal for a Diesel to not generate any excess heat when idling or under small load, like standing in traffic or going downhill. It doesn’t seem inconceivable that the outside air entering through the grill when going downhill for some time would cool the whole thing down.

I’m ready to give this a shot though. How can I test if the thermostat is stuck open? I know you can log data with VCDS like the coolant temperature, would that give any indication about thermostat operation (like, seeing a gradual increase in coolant temperature until 87C when it’s supposed to kick in)? I appreciate any pointers, I know the CJAA thermostat is a ***** to replace so I want to absolutely make sure that thats really what I’m dealing with here.

Thanks, guys!

PS: I’m sure the thermostat is not stuck closed because there are no signs of overheating. My best mental approach to this is that if the thermostat is bad, I won’t see a gradual increase in coolant temp because the fans would keep it cold from the get-go
 

ThomasCo

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One more piece of information that may/may not contribute to the answer. I did change to a 0W30 VW 507.00 engine oil whereas before it was some 5W40 Valvoline crap that the Toyota dealer that I bought the JSW from put in there. I did however notice the drop on the temperature gauge when going downhill with that oil as well. Specifically on the descent from Estes Park into Loveland which is some 15-20 miles of no throttle and only occasional brake action. Same on I-8 between Calexico (steep incline at 95 degree weather with AC blasting and radiator water stations every half mile) and the following descent into El Cajon.
 

JELLOWSUBMARINE

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One more piece of information that may/may not contribute to the answer. I did change to a 0W30 VW 507.00 engine oil whereas before it was some 5W40 Valvoline crap that the Toyota dealer that I bought the JSW from put in there.
That could be big. Was the Toyota oil 507 rated? That keeps me going back to a DPF (especially a weak one), having quick fill cycles, having to regen long and often. A constant gouge reading of some type would be very benifitial. Like was mentioned by Wilkinson sometimes its difficult to know when, how long or even if your even active regenerating.

You may want to chance taking it into the dealer, if your within warranty and you have issues with the DPF or other emmisions related item, its covered @ 0 deductible. Even if it turns out to be a wear item like the thermostat, most dealers will apply the usual hour of diagnostic cost to the repair. @ nearly 200k it could be multiple issues. A visit to a "good" dealership could actually save jot of $ and grief.
 

ThomasCo

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The Toyota "soup" that they put in was just a generic Valvoline 5W40 Diesel oil and not 507.00 certified (it would have to be 5W30 or 0W30 for that). That's why I changed the oil only 3,000 miles after buying the vehicle from them. They received the JSW as a trade-in from its original owner, who appears to have had it serviced either by VW or a European car specialist. Either way, I didn't want to take any chances and changed the oil and also flushed the DSG which appeared to be overfilled by a good amount when Toyota did it "to specs"
 

ThomasCo

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I apologize for getting all chatty and only providing bits and pieces at a time, but something woke me up in the middle of the night that I forgot to mention. When I flushed the DSG I had to remove the air filter box and noticed that in the back of the box, the bottom portion did not have anything connected to it, and there was a hose just dangling there. It looked like my friends at Toyota forgot to reattach it after they serviced the DSG, so when I was done with the transmission I attached that hose to the air filter box again.
 

JELLOWSUBMARINE

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The running behavior of these TDI cars was quirky from the beginning and it's even quirkier after the fix. Mine has over 180K miles and I owned it since it had only 6 miles on the odometer in early 2010. I love my little car, quirks and all!
You don't see many original JSW owners. This intrigued me so I looked at your past post. 2 years ago. @ 150k looks like you had your first DPF replaced? It also just had 8k since getting the fix that you needed a DPF. Did it seem to feel like the fix RE tune was the death nail to you? I would think the DPF would have been replaced @ the fix if it was that close then?? It will be interesting to see the new DPF lifespan now.

My CPO 69k 2011 had a new DPF so I put a non delete tune on it to preserve it. It was a tough decision but worth it. I think the "fix" will be the death of these diesels.

The Toyota "soup" that they put in was just a generic Valvoline 5W40 Diesel oil and not 507.00 certified. That's why I changed the oil and also flushed the DSG which appeared to be overfilled by a good amount when Toyota did it "to specs"
It seems hard enough finding a qualified VW dealer that knows these diesels around me anyway. I could only imagine what a totally unfamiliar sales department pushing it out for the bottom line would do. Sorry I don't mean to be Kurt about it but Id definitely take it in to a qualified VW dealer with a list of your issues and findings. It could possibly save you alot of $ while under warrenty.
 
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ThomasCo

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I just went for an 18 mile drive in sunny 55 degree weather. I did a VCDS log but need to figure out how to read it and generate charts from it. But to spoil the suspense, coolant temp only went up to 76C, fuel temp way below that. Upper radiator hose felt warm to the touch, lower (wide) one hot but not burning hot.
Average fuel economy @ 41.5 mpg according to MFI. 15 of the 18 miles were freeway speeds around 60-70 mph
 

JELLOWSUBMARINE

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I just went for an 18 mile drive in sunny 55 degree weather. I did a VCDS log but need to figure out how to read it and generate charts from it. But to spoil the suspense, coolant temp only went up to 76C, fuel temp way below that. Upper radiator hose felt warm to the touch, lower (wide) one hot but not burning hot.
Average fuel economy @ 41.5 mpg according to MFI. 15 of the 18 miles were freeway speeds around 60-70 mph
Almost sounds like the coolant isnt being pushed/circulated also. Uncommon but it does happen, the water pump can loose its veins.
 

ThomasCo

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OK I generated the charts from the logs: VCDS charts

It almost seems as if the thermostat is still opening/closing, but the thresholds (i.e., 87C for open) have shifted by about 20C. Interesting tidbit: while driving highway speeds around 70 mph the coolant temp is around 75C, stop and go and city traffic (as experienced on the way back) cause the coolant temp to go up to about 90C, only to drop again when longer periods of driving occur.

Also interesting: this 40ish mile round trip resulted in a calculated soot load increase of about 3g, the measured load stayed at 0 on the first trip and went up to 0.6g towards the end of the return trip (while in city traffic).

So... the $1 million question: what's my next step?
 

JELLOWSUBMARINE

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Wait wouldn’t that cause it to overheat?
Not necessarily. These engines are extremely thermally efficient.

In colder temps. you see it drop on freeway speeds. top/bottom temp. differential suggest its not circlating although the thermostate is open. ??
 

Wilkins

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Thomas that coolant temperature behavior is pretty much what I see. I’m not quite as cold as you are-yet. I think the explanation for the drop at freeway speed is the airflow through the radiator increases more than the cooling requirement increases. Since the thermostat is not doing it’s job of restricting the coolant flow the coolant temperature drops. I saw exactly the same behavior on my ALH and BEW,
replacing the thermostat solved the problem both times, and the thermostat was about 10 years old each time. For the record, 3 or 4 years ago my thermostat would maintain 85 C at highway speed with ambient close to 0 F. Below that the heater alone probably was sufficient to suck the engine temp down LOL.
I don’t think the thermostat will be covered by anything short of a full CPO warranty.

Jellow I am using Polar mostly, the “requested regens” or something like that is what goes 2-7, or maybe it’s 0-7. I should add my comments to your Polar thread but just haven’t got around to it. I’m also running Malone 2, save that for another thread.
 

ebain21

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I had my thermostat replaced under the emissions warranty while they were replacing the DPF. The dealer thought that since my thermostat was bad, the engine wasn't getting up to temp to trigger regens. I guess there is a tech bulletin about this. Have you had any DPF codes?
 

ThomasCo

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I had my thermostat replaced under the emissions warranty while they were replacing the DPF. The dealer thought that since my thermostat was bad, the engine wasn't getting up to temp to trigger regens. I guess there is a tech bulletin about this. Have you had any DPF codes?
No, I don’t have any fault codes whatsoever, but my Completed Regen counter is at 0. Would you happen to have that service bulletin available or linked somewhere?
 

ebain21

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I just looked at the service ticket and they didn't cite a specific TSB. I remember the service advisor saying there was a new TSB or other instruction from VW to monitor coolant temp, so they did that. I only mention because if your DPF goes bad, they may give you a free thermostat as well. Sorry I don't have more info for you.
 

ThomasCo

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I just looked at the service ticket and they didn't cite a specific TSB. I remember the service advisor saying there was a new TSB or other instruction from VW to monitor coolant temp, so they did that. I only mention because if your DPF goes bad, they may give you a free thermostat as well. Sorry I don't have more info for you.
You're fine, I appreciate the input. I called two nearby dealerships and both indicated that absent of a CEL or persisting DPF light this would not be covered at all, as nothing suggests any problems with the DPF. I decided to order the parts @ FCP Euro and am looking forward to replacing the thermostat myself this coming weekend. It'll be a nice project with a purpose, and the price for all the parts combined is cheaper than the diagnostic fee at the dealership.
 

ThomasCo

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Update: I replaced the thermostat and did a complete coolant flush because the goo that was in the depths of the cooling system was orange. I am happy to report that the vehicle is now getting up to and holding an operating temperature of around 95C. Also replaced the serpentine belt while I was in the “vicinity” because mine had a pinhole in it.
 

jesus_man

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It seems my turn for a thermostat replacement, but I will attempt to figure out how to verify that with VCDS reading temps. I need to figure out how this is done and how to properly perform the test.

I believe the open t-stat is the cause of the car not performing regens. I think it's first winter in ND did the t-stat in. So did replacing the T-stat allow the engine to run more consistently at normal operating temps and then allow for a successful regen?

Do you have a procedure for flushing the coolant system? I'd like to perform that, but not sure it's something I can do in my home garage due to trying to get rid of the old coolant.

Lastly, I have seen videos and tutorials for removing the T-stat. Lots to remove, but there are some hoses that are difficult to remove. Did you find that as well? What other parts did you remove in order to access the T-stat and were there other gaskets to replace or does the part come with all you need?

Thanks!
 
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