Cylinder Head Temp Sender Wire

["Russell Neithammer" <rneithammer@xxxxxxxx>]

I had the exact same problem when I recently installed my VDO CHT gauge.  I
was on a schedule, so I didn't stop to ask any questions.

This gauge/sender is a thermocouple.  The gauge is driven directly by the
voltage produced by the thermocouple - no external power required.  The 12V
connection at the gauge is for lighting only - the gauge will read the
temperature with or without the 12V connected.

Since the the signal from sender to gauge is a voltage at very low current,
I reason that a small increase in wire length/wire resistance has very
little (read, no significant) impact on the gauge reading.  To make things
as accurate and reliable as possible, I soldered all of the connections,
including the replacement push-on spade terminals I installed at the gauge
connection, and I insulated everything with heat shrink tubing.  I used 16
AWG hook wire from the local FLAPS.

My gauge starts to come up within about a minute after starting the engine.
This makes sense to me, since the low end of the scale is 100 deg F.  I
expect that as the outside temps get cooler, this will take slightly longer.


Date: Sat, 8 Sep 2001 23:51:48 -0500
To: type2@xxxxxxxxx
From: Stan Wilder <wilden1@xxxxxxxx>
Subject: Cylinder Head Temp Sender Wire
Message-ID: <20010908.235149.-451503.2.wilden1@xxxxxxxx>

I just installed a cylinder head temp gauge and sender with the VDO
Sender, Installation Kit and 600 degree gauge.
I've been searching the archives and came up with this.
---------------------------
The Question:
My real question is when I installed the sensor I hooked up the (heat
sensor wire) the to wires going
to the gague, but I ran out of wire so I added about 2-3 feet of wire to
the orignal wire that came with the VDO gague. Will adding this wire give
me false readings??

He got his response:
If you add it at the gauge end, it shouldn't change the readings
appreciably as long as there is no resistance in the wire you added.
---------------------------
Now for my question:
How long does it take to start getting a reading on the temp gauge?
Is this true about adding extra wire length?

Stan Wilder
83 Air cooled Westfalia