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Subject:Coolant gauge calibration
From:David Marshall
Date:Thu, 21 Oct 2004 20:32:43 -0700

In the course of doing my engine conversions I notice that the coolant gauge
is never in the same place when I am done.  The TDIs always read higher in
the gauge as compared to the wasserboxer would read.  The coolant gauge is
neat, but it doesn't tell how hot the water really is, it is more or less an
indication of how hot things are and to me, that really isn't good enough!
:-)

AHU TDI / AAZ TD / ABA 2L [Jetta III]
Normal temp has the needle above the LED with just enough space to say there
is some space there.  This would be looking at a coolant gauge in a
tachometer equipped Vanagon.  With VAG-COM [diagnostic tool] I can see that
this level is about 97C and 80C being at the LED or just slightly low on the
LED.

ALH TDI / AWD 1.8T / AEG 2L [Jetta IV]
These tend to make the gauge read even higher, to the point where the LED
starts flashing at you, indicating that the temp is too high.  In reality
VAG-COM reports a nice 97ish Celsius degrees.  Installing a 100 to 150ohm
resistor brings the needle down to where the LED is and the LED stops
flashing.

CALIBRATING THE NEEDLE
To make the needle read lower, all one has to do is insert a resistor inline
with the coolant sender.  The more resistance, the lower it makes the needle
in the gauge.  My questions to the list are:

- Where does your wasserboxer coolant needle 'sit' when driving on a normal
road, normal weather and everything is just 'normal'?
- What really is the wasserboxer's coolant temperature when you are driving
and everything is normal?
- Does the needle sit at different places on different years of production?
- At what temperature is the 'too hot' LED supposed to come on at?

Thanks in advance for your answers!

David Marshall

Fast Forward Automotive Inc.
4356 Quesnel-Hixon Road
Quesnel BC Canada  V2J 6Z3

http://www.fastforward.ca    mailto:sales@fastforward.ca
Phone: (250) 992 7775        FAX: (250) 992 1160

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