cooling question.

Discussion in 'Mech Tech' started by cabbieman, Aug 21, 2011.

  1. I know we call them air cooled but strictly speaking it should be oil cooled right? If you are say on a motorway and stuck in traffic ( honestly, it does happen) tootling along at say 3 to 4 miles an hour, how concerned should i be that no air is getting the opportunity to circulate and cool the engine down.At what point do I start to think my engine could overheat?
     
  2. Poptop2

    Poptop2 Administrator

    The oil won't keep it cool for long has many a unwary dubber has found out in that situ , best to turn your motor off if poss dude !.
     
  3. Doesnt the fan suck the air in when your static?? Ive often wondered about this too but presumed the fan had enough power to cool the engine even when static? Is that not the case and should I be stopping and starting the engine? :-[ :-[
     
  4. if you turn off a hot engine then the fan doesn't spin

    if the fan isn't spinning then there is no cooling air over the engine

    that heat will stay in the engine and will only slowly cool down

    by your logic all VW stationary engines will over heat as they don't move
     
  5. Poptop2

    Poptop2 Administrator

    My logic has never cos me a engine yet -- and i have probably done more miles in reverse than some have done forwards !!.
    it was the only way we could keep her cool in southern Italian traffic jams !.
     
  6. why would driving backwards cool your bay more that driving forwards ?
     
  7. Gotta say my engine is reasonably cool on tick over, and heats up when its switched off, the fan seems to cope quite well with keeping the engine cool -touches head and says touch wood- that said took the van for a spin today, about 20 miles pulled into a car park and got out to check the temp, pulled the dipstick and wiped it with my fingers and the oil was hot but not scolding and the dipstick was just warm, i'm taking this as a good thing ;)
     
  8. Poptop2

    Poptop2 Administrator

     
  9. Honky

    Honky Administrator

    Like others have said - it should suck up air even when stationary.
     
  10. Birdy

    Birdy Not Child Friendly

    There is no need to worry. This is why the heads are finned to help trap cooling air to aid cooling. The fan will cope well at idle to cool the engine.

    With the comment "they are oil cooled" that is correct but wrong. A water cooled car has a cooling system that runs avoid the heads. The oil doesn't. It's the air that does it. The oil is cooled because as at as l can see, air-cooled engines run a little hotter than water cooled cars.
     
  11. Keep it running in stop start traffic as the only thing keeping it cool in those circumstances is the engines fan
     
  12. Ok, thanks guys. I will drive with a bit more confidence now on our sun drenched journeys in England ::)
     
  13. Last Monday I spent 2 hours in stop start traffic on the M25. As long as all the tin wear is in place, and the engine bay seal is good these air cooled engines will tick along all day stationary and stop start traffic.


    The clever thing about these engines is that the cooling fan supplies the correct amount of cooling what ever the engine speed. As the engine speed ( revs) increase so does the fan speed and therefore the amount of air flow to cool the engine. It's really simple but works really well.


    The only way to over heat a well maintained engine, is to put it under a lot of load at slow speed. ie up a long hill with your foot to the floor in 4th. In this situation the engine revs would be low, but the amount load on the engine is high. Therefore low fan speed but high cylinder temperature. Solution, change down a gear.


    Another tip. opposite to a water cooled engine, if you think your getting a little too hot, change down a gear and increase the revs. this will increase the fan speed and therefore the cooling.
     
  14. If you're sitting in traffic, you're in a better position than watercoolers. At idle, the fan is still blasting cooling air past the heads and out the back and through the oil cooler and out the front.

    They're both air and oil cooled, but the main mechanism for getting rid of heat from the hottest parts (the cylinder heads) is the great blast of air down past them.

    As above, change down and give them plenty of revs when you're under load going uphill, so the fan provides plenty of air to the heads just when it's needed.

    No need to fret!
     
  15. rickyrooo1

    rickyrooo1 Hanging round like a bad smell

    one thing that's puzzled me since owning these - bear in mind i hadn't even looked at the engine on an air cooled before may this year (apart from on telly) how, if they cool by being enclosed, (and by this i'm told it's bad to run with the rear hatch open or the engine bay seal missing) do them beach buggys not overheat? their engines are open and i don't see much difference, also you see some beetles with the rear hatch "on the latch" driving along, and also, hully's bus (ex corky) the porschefalia has loads of holes cut in the hatch behind the numberplate.
     
  16. The Porker engine cools in the opposite way to the VW, ie from the rear of the engine...
     
  17. rickyrooo1

    rickyrooo1 Hanging round like a bad smell

     
  18. When you turn you engine off the cold zone temp raises quickly so I would not recommend switching the engine off and on in traffic.


    If you have been stuck stationery for a while opening the deck lid to let some of the heat escape wont be a bad idea (when I do this I can see it drop on the oil temp gage) but make sure you close it before you drive off or the cool air blowing in to the engine will come straight back out.
     
  19. Poptop2

    Poptop2 Administrator

    Gosh there's a lot of faith in the cooling systems in this thread , your probably right in the uk its not that hot , but increase the ambient temp and mix it with a weak fan and they get hot hot tot .

    Cost a friend a lot of money to get a engine in France once , the vw mechanic said it was overheating that had caused the problem , he later told me he had been stuck in traffic for most of his journey - he was a tight git and used the nationals to save money - ooops
     
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