Engine & Gearbox Fan Running for a Couple of Minutes After Switch Off

Discussion in '8th Generation (2008-2015) [Acura TSX]' started by John Dickson, Saturday 30th Aug, 2014.

  1. John Dickson Club Veteran ★ ★ ★ ★ ★


    This is probably a silly question - particularly to those who know more technical aspects.

    Just been for a short run in the car no more than 5 miles to the shops etc.

    Got back home and unloaded the car so that would take a couple of minutes. When I was finished I heard something running so went to front of the car and the cooling fan (or what sounded like it anyway) was running but it did cut out after maybe 15 seconds after I noticed.

    Now I know the old air cooled Renaults etc used to do this and a mate of mine had a Volvo 340 with the air cooled Renault 1.7 engine and it used to do this.
    in fact he used to have to take it on a fast run immediately before switching off if he wanted it to start again within the next few hours.

    I've never noticed any of my previous petrol Accords do this so I wondered if this was something particular to the I-DTEC, to cool the intercooler perhaps?

    Perhaps they did but I never noticed.

    It wasn't a long run like I say but wasn't a particularly high speed run either so not much flow of air through the radiator.

    Cheers! :Thumbup:
  2. T10KJC Club Member ★ ☆ ☆ ☆ ☆

    This happened to me a couple of weeks ago . I had just drove from Stoke to Glasgow & also herd the cooling fan , after a long run always let the engine cool down for at least 30 sec,s & low rev,s before that .
  3. John Dickson Club Veteran ★ ★ ★ ★ ★

    Hello Kev,

    Yes I always tend to let the engine idle for a while before switching off as I also run the fan at full with the air con switched off to purge the system.

    Always believed in letting it idle after a run even with normally aspirated petrol cars but even more so now with the I-DTEC to let the turbo and turbo bearings cool down.
    T10KJC likes this.
  4. narcosis Senior Member ★ ★ ☆ ☆ ☆

    I have had this once before and wondered if it was part of the DPF regen! I didn't have any problems afterwards.
  5. John Dickson Club Veteran ★ ★ ★ ★ ★

    I wonder if it is? Never thought of that. Never noticed the DPF doing a regen but could that have been what was happening I wonder?
  6. narcosis Senior Member ★ ★ ☆ ☆ ☆

    TBH I have never noticed the car doing a regen ever, I assume it just gets on with it given the right conditions.
  7. T10KJC Club Member ★ ☆ ☆ ☆ ☆

    I have never noticed my car doing a regen, ReadIng other people's comments I thought there would of been a lot more noise .Took for granted it was the cooling fan what do you think John Dickson.?
  8. John Dickson Club Veteran ★ ★ ★ ★ ★

    To be honest guys I'm still a novice to diesels only been driving one in any sort of major amount for about a year.

    I agree with both your comments I have never noticed the car doing a regen.

    My (albeit very basic) understanding is that providing you do the correct type of driving in order to ensure the DPF is getting sufficiently hot enough, for sufficiently long enough the DPF light will never come on and the DPF regen cycle as such will not start as the light coming on means the car hasn't been able to auto-regen and needs to run its in built regen cycle. What I mean is if you're doing the right sort of driving, the DPF is continually burning off the accumulated soot particles and is just a continual process and therefore the DPF regen cycle never has to run or it takes a significant amount of mileage and therefore soot build up before it will start. I'm on 7,000miles of mixed urban, A road, motorway and round the doors driving and I've never had the DPF light on - yet. Not wanting to tempt fate! :lol:

    When people run into problems my understanding is that this is due to them not driving the right mix of driving to justify a diesel and therefore the soot build up becomes excessive, or it is due to mistakes such as incorrect oil, mis-fuel with petrol, skimped servicing etc.

    A colleague at work has just had to replace DPF on an 09 Insignia that he bought from one of the other lads. This was a low-ish miler but the first owner mainly did home-work-home, 3 miles each way Monday to Friday and maybe a longer run on the weekend or less occasionally a bigger run. This is basically DPF suicide! In my novice opinion, to maintain a healthy DPF you need to do around a minimum of 30 miles a day regularly, in there a decent 10-15 mile run, so that the DPF has the slightest chance of getting hot enough. Otherwise you're probably storing up trouble in the long run. If you do less than this why do you even want a diesel? You'll never recoup the additional outlay.

    What I have noticed, apart from the fan running on after switch off in this one off example, occasionally is a burning smell when I got out of the car - similar to binding brakes. Perhaps this was the DPF burning off soot accumulation - I don't know. It's not binding brakes I'm certain of that as the discs do not show any signs of binding brakes.

    This is just based on my assumptions about DPFs from talking to the technicians at Newcastle Honda and from what I've heard fro other people. I need to really read the DPF material on here.

    Perhaps the more experienced diesel members can correct the above if I'm wrong or elaborate on my very limited understanding.
  9. SpeedyGee Administrator Staff Team

    England Speedy Birmingham
  10. John Dickson Club Veteran ★ ★ ★ ★ ★

    Cheers Speedy. :Thumbup:
  11. T10KJC Club Member ★ ☆ ☆ ☆ ☆

    Great comments & feedback
  12. i-DSI Club Veteran ★ ★ ★ ★ ★

    Belgium Aalst
    Hi John,
    I might say my technical car level knowledge is quite high, especially Honda knowledge. And: I can not explain why the fan would be running after switching off the ignition if you drove only a few miles in a normal way. I don't say something is wrong, I just can't tell why it should keep on running. I have never ever known this in my Accord petrol and if it is the cooling fan: it should only keep on running if the coolant temp is 'high' (not the same as 'to high'!) at the moment of ignition off.
    If you ever notice this again: open the hood and have a look at which of the 2 fans is running (airco, engine or both).
  13. Phil P Premium Member Club Supporter

    United Kingdom Phil Kent
    Assuming my CR-V has the same basic diesel engine as yours I have had the fan running on, after turning the ignition off, twice now in 18 months of ownership.. I didn't realise at the time but it was doing a DPF regen (which I wouldn't usually notice when driving, apart from a little blip in MPG) . The smell of burning particulates and hot metal gave it away when I stepped out of the car. Presumably the fan stays on to cool the super-heated bits down.

    I asked TDK what this was all about when it first happened. Quite normal apparently.

  14. i-DSI Club Veteran ★ ★ ★ ★ ★

    Belgium Aalst
    Hi guys,
    As far as I know the engine temp itself does not (or hardly) rises when regenerating. For regeneration you only need a very high exhaust temp. To achieve this, a little extra fuel is injected just a bit to late so it burns (or is hardly cooled down) when leaving through the exhaust valves. But in the case of John's car, the car could never start any regeneration because he hardly drove a few miles. And engine temp must have reached normal operating temp before a generation is even started.
    So this particular case remains a mistery to me.
    The case you describe (or TDK) seems normal: engine has been shut down while still hot, so fan kept on running.
    Phil P likes this.
  15. T10KJC Club Member ★ ☆ ☆ ☆ ☆

    That's reassuring to know that in my case it was doinga regeneration thanks for the info .
  16. John Dickson Club Veteran ★ ★ ★ ★ ★

    Hi Geert thanks yes I never noticed this happening on my petrol Accords but I'll keep an eye on it and see if it happens again and I'll look at which fan is running. I think you're right about the engine temp when doing a regen. My understanding is it is only the exhaust gasses that need to get hot enough. If the engine isn't hot enough a regen couldn't happen as the engine needs to be hot enough to allow the slight extra bit of fuel to raise the exhaust gas temperature enough.

    Hi Phil yes I think the Accord 2.2iDTEC and CR-V I-DTEC engines are the same. I'll see if this happens again sounds like it was similar to a regen but I'm honestly not sure if it would've been hot enough or not. It was a very warm day though so the engine could've warmed up faster I suppose.
  17. Ichiban Founder Staff Team

    England CJ Leeds
    John this is quite natural mate the ECM software all all newer 2012 I-DTEC have this inbuilt in to cool the engine when a DPF natural regen was occurring but the owner has switched the car off. Look at the 4th Generation CR-V FAQ this is quite clearly noted.

    This is primarily to get the temperature down in under the hood as its so hot it can cause combustion if the car is parked on dry grass..
  18. John Dickson Club Veteran ★ ★ ★ ★ ★

    Thanks for explaining CJ.

    Sounds like this natural regen can occur at any time then even during a short run providing the concisions are correct. The symbol never came on on the MID though definitely.

    I assume the car would just continue the regen next time it was running and the conditions were again correct?

    It will have definitely had a good clean out last week up in Scotland 850 miles over 3 days :lol:
    - - - Updated - - -
    I'll look at the CR-V section
  19. Ichiban Founder Staff Team

    England CJ Leeds
    Natural regen never come up on the dash the dash warning are when things are not right, yup the regen will happen again when the parameters are met , heavy right foot tune mate always helps.