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RE: [T3] Tune Up & Brakes


I was talking about the rear of the engine, from the aluminum fan housing to
the heat exchanger air input orifice.

But!

I'll try to explain myself in regards to your engine (engine cooling flaps
missing) but it'd be a helluvalot easier in person...

Air comes from the fan...
-If the heating flaps are closed then the air has no where to go 	XG_ir
spills through the cooling flap entrance and over the cylinder heads -- the
air in the heat exchangers and forward is blocked off and has no where to go
so it acts to block more air from entering.

-If the heater is on, air flows into the cabin, sooooo the air will more
readily enter the heat exchanger and bypass the cooling flap entrance.
(Since air flows much like water it takes the easiest route, thus straight
to the heat exchanger instead of a 90-degree turn to the top of the
cylinders.  Now, in reality, air does go over your cylinder heads, but not
much at all).

Okay, another reality check:  There is a vent at the top, front, of the heat
exchanger where the heating flap is.  When the heating flap is closed (no
heat to the cabin) this vent is open and *some* air will, indeed, flow out
of it and into the atmosphere.  This keeps a *small* air flow moving through
the heat exchanger so it won't overheat due to internal stagnate air.  When
the heating flap is opened most of the air will enter the cabin but some
will still go through this vent.  When the heating flap is open ALL the way
this vent will be sealed by the flap and ALL the air in the heat exchanger
will enter the cabin.

What's this mean to you?  Well, if your heating flap is *fully functional*
then you can rest assured that this isn't contributing to your problem.  If
it's missing or not sealing properly then you have a problem -- more so if
it's missing!  If it's missing then the cooling air for the right side of
the engine is going into the atmosphere (after being heated by your heat
exchanger) and the engine will overheat on that side (oh! pew!).

Will this contribute to overheating of the engine as a whole?  You betcha!
The right side more than the left, but heat 'flows' and the oil and air and
metal all assist in this flow to the left side.

Whew!  Well, I hope this little information on how the heat exchangers can
affect engine cooling helps (someone).

   CC replies to: None, as I get messages right away.
   Toby "I'm telling ya, I s暡S~one for a mechanical degree" Erkson
   air_cooled_nut@pobox.com  <-- Please use this address for email
   '72 VW Squareback 1.6L bored and stroked to 2.0L, Berg five-speed
   '75 Porsche 914 1.8L, R.I.P., ORPCA member
   '95 VW Jetta III GL 2.0L, P-Chipped, Jamex sport suspension
   Portland, Oregon, http://www.pobox.com/~toby_erkson/


> -----Original Message-----
>...
> 	Are the hoses connected between the cooling fan
> 	shroud and the heat exchangers?  
> 
> 	<<<Do you mean from the back of the J-tube to the 
> heater channels
> under the doors?  If that is the case, I *am* missing the one on my
> passenger's side.  I didn't even think this would be a 
> problem, as it's past the engine itself.

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