Radiator fan running after short drive

[mxtdiguy]

Just drove around town today, not even going over 40mph, partial throttle but when I returned home, the radiator fan ran for maybe 5 minutes afterwards as if the motor was hot.

Outside temperature is only 70 degrees or so.

No warning lights or anything on the dash.

2016 TDi with only 3k miles on it.

This seems to the first time it has done this, it is normal ?

Not alarmed, just curious, I thought tdi's generally ran "cool" unless pushed hard.

Also, the idle is a little high at 1000 rpm.

Thanks for any input

 

[jonferns]

Sounds like it was performing a regen. Probably not the first time it's happened, but the first time you've noticed.


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[mxtdiguy]

Sounds like it was performing a regen. Probably not the first time it's happened, but the first time you've noticed.


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Thanks

Is there anything I should be doing to "help" the regen process if anything at all ?
Drive longer ? faster ? full throttle at times ? or ignore ?

How long does the regen process take ?

 

[VeeDubTDI]

I recommend letting it finish before turning off the engine. Some people like to drive around, but idling in the driveway has always worked fine for me.

You can monitor regeneration activity with a ScanGaugeII or other OBDII diagnostic data display.

There are numerous threads about this topic throughout the Mk6 and NMS Passat forums if you're in the mood for some long reads through recent history.

 

[mxtdiguy]

I found this helpfull article:

http://uk-mkivs.net/topic/31023-dpf...st-read-for-all-drivers-of-dpf-equipped-cars/


Quote:

Question: Under what conditions is regeneration
interrupted/ended once it has started?

Answer: Normally when
regeneration has been successfully completed, or:

a.) After a
maximum regeneration time (20 - 25 min.).
b.) If the engine is
switched off or has stalled.
c.) If the engine is left idling for a
long time (5 - 10 min.).
d.) If 1000°C is detected by the exhaust
temperature sensor.
e.) If during regeneration, a fault is detected
on the components relevant for combustion (injection/intake system).


So it appears that regeneration can be stopped by just idling the engine ?

Mine has been idling for the last 15 minutes and the idle is still at 1000 rpm, so I don't know if I should continue to let it idle..

 

[Lightflyer1]

Touch the throttle and release. Then see if it returns to normal or 1k rpm.

 

[VeeDubTDI]

I found this helpfull article:
http://uk-mkivs.net/topic/31023-dpf...st-read-for-all-drivers-of-dpf-equipped-cars/
Quote:
Question: Under what conditions is regeneration
interrupted/ended once it has started?
Answer: Normally when
regeneration has been successfully completed, or:
a.) After a
maximum regeneration time (20 - 25 min.).
b.) If the engine is
switched off or has stalled.
c.) If the engine is left idling for a
long time (5 - 10 min.).
d.) If 1000°C is detected by the exhaust
temperature sensor.
e.) If during regeneration, a fault is detected
on the components relevant for combustion (injection/intake system).
So it appears that regeneration can be stopped by just idling the engine ?
Mine has been idling for the last 15 minutes and the idle is still at 1000 rpm, so I don't know if I should continue to let it idle..

Idling alone will not stop a regen. Eventually it will finish. The RPMs will not return to idle until you blip the throttle.

Best bet is to monitor exhaust gas temperatures. I generally let everything drop below 400 degrees F before shutting off the engine. Depending on outside temperature, how hard I've been driving, and if the vehicle was regenerating, it can take anywhere from 15 seconds to 10 minutes of idling for everything to cool down.

Of course, you're free to do what you want. Cool down, in my opinion, is a best practice. Turbos don't like being shut down hot. Coolant can also overheat and degrade in the hot EGR cooler if EGTs are high. Keep in mind that regeneration EGTs and full-load EGTs can be 1,400 degrees F. Stopping all oil and coolant flow at those temperatures is, again in my opinion, a bad thing to do.

 

[Lightflyer1]

That quote came from "Courtesy of David Bodily Volkswagen Technical Support Specialist" at the other post. Do you have any source that backs up that idling won't stop a regen? Not doubting you but would like a source.

 

[VeeDubTDI]

That quote came from "Courtesy of David Bodily Volkswagen Technical Support Specialist" at the other post. Do you have any source that backs up that idling won't stop a regen? Not doubting you but would like a source.

My source is me putting over 100,000 miles on one of these machines and routinely letting regenerations finish at idle in my driveway (due to living that magical distance from work that allows a regen to get started about two miles from my house).

Perhaps the 2015 TDI behaves differently from my 2012 Passat, but my observations seem to align with others reported on TDIClub over the years.

 

[demagxc]

Doesn't the 2015 have an oil pump that continues to circulate oil through the turbo after the engine is turned off? I used to make sure I let the regen finish before shutting off the car but after 10 thousand miles of doing that I had enough. I monitor my temps but wont think twice about interrupting a regen.

 

[mxtdiguy]

Doesn't the 2015 have an oil pump that continues to circulate oil through the turbo after the engine is turned off? I used to make sure I let the regen finish before shutting off the car but after 10 thousand miles of doing that I had enough. I monitor my temps but wont think twice about interrupting a regen.

That would be nice to know. The fact that I can't lock the doors while idling also makes it less likely that I want to wait to let it idle for long.

After driving fast recently for an extended stretch, the radiator fan was not on when I pulled over for a stop. Is it safe to assume the air flow at the high speed was enough to keep coolant temps in the safe range, ie, not much idling time is needed ?

On a side note, if the car were stolen while idling, can it driven indefinitely until turned off even though there is no key inside ?

I'm also curious about the comment in the article about long downhill decents, is it because the high air flow with low load means EGT's are not high enough to continue the regen ?

Thanks for all the replies.

 

[1854sailor]

I just drive around until I see the temps on the ScanGauge return to normal. But then, I'm retired ...

 

[VeeDubTDI]

Doesn't the 2015 have an oil pump that continues to circulate oil through the turbo after the engine is turned off?

Nope.

 

[surfstar]

Nope.

The gassers do, why not the TDIs?

 

[demagxc]

Nope.

I was under the impression that the humming/buzzing noise you hear when you shut off the car was the circulation pump running. There seems to be a lot of conversation about this for the gassers but since there are not nearly as many people discussing the TDI I always assumed same noise=same function

 

[Jedadiah]

You can lock the door while idling, but you first have to make a change with vcds have to have two remotes with you.

Open central convenience, open adaptations, and search for “Funk bei Klemme 15 ein.” Change it to active, and your remotes with now work when the ignition is on.

 

[mxtdiguy]

You can lock the door while idling, but you first have to make a change with vcds have to have two remotes with you.
Open central convenience, open adaptations, and search for “Funk bei Klemme 15 ein.” Change it to active, and your remotes with now work when the ignition is on.

Thanks for the tip

"Funk bei Klemme ein"

Almost sounds a worthy bumper sticker

 

[VeeDubTDI]

The gassers do, why not the TDIs?

The gassers do not have an electric oil pump. Some of them might have electric coolant pumps that circulate coolant after the engine is shut off, but those have water-cooled turbochargers, which the TDIs do not have.

 

[surfstar]

The gassers do not have an electric oil pump. Some of them might have electric coolant pumps that circulate coolant after the engine is shut off, but those have water-cooled turbochargers, which the TDIs do not have.

Ah, that makes sense now.

 

[mxtdiguy]

You can lock the door while idling, but you first have to make a change with vcds have to have two remotes with you.
Open central convenience, open adaptations, and search for “Funk bei Klemme 15 ein.” Change it to active, and your remotes with now work when the ignition is on.

Has anyone come up with a timer ? That would really be a nice addition. Lock the doors, walk away while it idles for a set time.

 

[740GLE]

Doesn't the 2015 have an oil pump that continues to circulate oil through the turbo after the engine is turned off? I used to make sure I let the regen finish before shutting off the car but after 10 thousand miles of doing that I had enough. I monitor my temps but wont think twice about interrupting a regen.

heat is generated post turbo in the DPF itself, turbo temps during a regen at idle aren't that detrimental to the turbo in all 2009-2015.

There is coolant that circulates the head after shut down to keep things form thermal run away.

 

[740GLE]

Has anyone come up with a timer ? That would really be a nice addition. Lock the doors, walk away while it idles for a set time.

no timer needed unless you run crap for oil, run good oil and don't shut down directly after climbing a 5 mile 15% grade at 75MPH in 6th. EGTs fall so fast if you coast any sort of distance more than 2 min.

 

[VeeDubTDI]

heat is generated post turbo in the DPF itself, turbo temps during a regen at idle aren't that detrimental to the turbo in all 2009-2015.
There is coolant that circulates the head after shut down to keep things form thermal run away.

You must be thinking of a VR6. AFAIK, TDIs have no after-run coolant pump.

 

[VeeDubTDI]

no timer needed unless you run crap for oil, run good oil and don't shut down directly after climbing a 5 mile 15% grade at 75MPH in 6th. EGTs fall so fast if you coast any sort of distance more than 2 min.

Unless it's actively regenerating, in which case the EGTs do not fall and stay at full-load levels any time the engine isn't in overrun.

 

[compu_85]

You must be thinking of a VR6. AFAIK, TDIs have no after-run coolant pump.

Yes... some gassers have after run pumps, but the pre-15 TDIs don't. The 2015s do have an electric water pump for the cylinder head circuit.

-J

 

[VeeDubTDI]

Yes... some gassers have after run pumps, but the pre-15 TDIs don't. The 2015s do have an electric water pump for the cylinder head circuit.
-J

Good to know. Perhaps that's VW's attempt at addressing some of the coolant breakdown issues they've been having on TDIs in recent years.

 

[adjat84th]

I've never heard either of the auxiliary water pumps run after shutdown myself, though maybe they do in certain situations I've not encountered.
The front is just for the charge air cooling circuit, and the rear for the heater core/cylinder head circuit. They are pretty quiet, but can be heard when under the hood and they're running. You can run them with VCDS to help fill the system after a drain which is nice.