[Vwdiesel] Direction of coolant flow in radiator

LBaird119 at aol.com LBaird119 at aol.com
Thu Sep 2 23:15:03 EDT 2004

> as much as i respect your opinion, and i think that
> you have much more experience in these things than i
> do, but this time i think you're wrong.

  It indeed does look that way.  Not my opinion though.  That's what I 
was told by our service manager when I worked at the dealer.  He was 
actually pretty good, it sort of made sense since the T-stat was down 
there in reverse position and so on.  I just never thought it through, 
found a flow diagram or tested his claim.

> if it were to pull from the top of the radiator then
> as soon as the coolant level were a little bit low
> then it would be sucking air. yes, it is a closed
> system, but if it were taking from the top of the
> radiator then the radiator would ALWAYS be full, until
> the time when the engine were completely empty of
> coolant. and the head of the engine would be the FIRST
> thing to be lacking in coolant. not a good recipe for
> an aluminium head.

  Makes perfect sense.  If the reverse were true it'd help explain why 
we see so many blown head gaskets though!  ;-)
  I found a flow diagram in my '85 (only) Bentley.  Great book, it's bigger 
than the '85 through '89 one I have!
  From the reservoir coolant goes to the heater core return and trans 
cooler (if you have one).  Trans cooler then goes to heater inlet which 
comes from the #4 end of the head.  Heater return goes to the pump 
inlet and picks up oil cooler/heater return (if).  Pump goes into the block, 
out the side of the head and back down to the pump and into the top of 
the radiator.  Out the bottom of the radiator into the pump as well.  It 
doesn't show how the stat fits in as it has a dual "flap" that closes one 
passage as another opens.

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