Re: Evans (Zero-pressure) coolant -Reply

[Igor Kessel <e6941tb@ix.netcom.com>]

Gross Scruggs wrote:
> 
> Igor, good work!  It'll be interesting to see how clean your system stays with
> the new coolant, likely cleaner if the new coolant carrier less oxygen in it.
> Other than the open cap, were there any required modifications?

None, that was the beauty of it.
 
> As I recall, the original Evans cooling system also used a reverse flow water
> pump.   Pushed the 'cool' water to the head first then down the block and back
> to the radiator.  Said temperature distribution along cylinder walls was more
> even.  One might have to search a very long time to find a reverse flow water
> pump for an I5 Audi.

I heard it too, but I have been told that it was really necessary only in the 
extreme racing apps.
My Audi runs well without reversing the flow, which is rather convenient.

> Also, one of the advantages of the Evans system was that they could run their
> short track super modified engine at a much higher temperature for better
> efficiency without the potential of a pressurized system blowing and the
> temperature soaring to engine destruction.  Have you considered running a higher
> thermostat?

Now that you've mentioned it... I indeed have the coldest available Audi thermostat 
installed (79°C). Might try to return to the OEM (87°C).
BTW, there's indeed one more mod that is recommended, although it is not essential:
I drilled 4 holes, 3mm ea in the thermostat, to allow some coolant flow at very low 
temps. 
That blue Evans is rather thick @ 20°C, and I can only imagine it's density @ -20°C.
 
> Wonder if there is an alternative source for the coolant to get around the
> $27.50/gal, perhaps bulk drums from the chemical houses.  What is the coolant?

Propylene-Gycol with something. I measured it's Specific Gravity: 1.040 @ 26°C.

> I, too, replaced the plastic OEM heater valve with the Pep Boys all-metal
> valve...  which is actually half plastic, but anyway.... but noticed before
> installation that it didn't close.  Disconnected the wire rod from the lever and
> bent the rod probably 30deg before it closed and opened all the way.

Yep, I first tried the Pep Boys unit. Returned due to this reason and because it was 
half-plastic. Maybe should've kept it.
The all-metal one, which I got from National Auto, is a totally sealed unit, no 
moving parts. I can't tell if the vacuum closes the valve all the way.

OTOH, the winter is coming and it will be my wife who gets to drive the 200TQ from 
now on. And since she thinks that anything colder than 30°C ambient is chiliiiiiing, 
I don't have to adress the heater valve till next July.

-- 
Igor Kessel
'89 200TQ - 18psi (TAP)
'98 A4TQ - already in the port of entry (Boston). Any day now.
Philadelphia, PA
USA