[T3] 73 T-3 oil temp?

William Jahn willjahn975 at gmail.com
Wed Sep 8 10:36:54 PDT 2021

I looked at Gene Bergs site last night and this is the main part . " I have
run hundreds of accuracy tests on practically every inexpensive aftermarket
gauge under $125 offered. Practically all read low in the 212 to 260 degree
range by 40 to 50 degrees on oil temperature and head temperature gauges in
the 250 to 550 degree reading range, again being low by as much as 250 or
more degrees. I tested about twenty each of most brands such as VDO, Smith,
Stewart Warner, Hawk, etc., and found none without these problems.

Oil temperature gauge readings would be 212 to 220 degrees on the gauge
when the true test temperature was 240 to 260 degrees. Head temperature
gauges read 385 degrees with a true test temperature of 550 plus degrees.
When head test temperatures were upped to 700 degrees, the reading of the
gauge went up to 390 to 395 degrees. The price range of such gauges was
from $60 to $125. I swapped gauges with senders and got different readings.
I found nothing in that price range I would wish on my worst enemy. Not one
I tested could ever be properly calibrated or relied on in any way for any
valid information or even as a comparison from day to day on the air cooled

 This is the video I saw talking about the VDO temp gauge sensor in the oil
cooler bypass spot.

 He mentions Gene Berg , talks about the thermometer down the dipstick. I
really question his  knowledge. He never actually shows any tests or offers
any proof.  If you want to watch it do let me know if you see and hear.
what I do.

 I can test the sensor in boiling water to see what the ohm reading is. I
Realize boiling point changes at altitude so I need to find a chart . The
other thing I need to do  to really know is heat the sensor to 212F and to
actually know what the gauge reads. In order to do this I would need to use
a hot plate to boil the water , and have the sensor connected to the gauge
to know what the gauge actually reads. The only info I have is 700 ohm cold
and 22 ohm warm. I guess I could get the sensor to 212F, check the ohm
readout then use a variable resistor set to that value and see what the
temp gauge reads. That may be the easiest solution.

 All the decades VW never had more than an oil light and people lived with
this and it seemed to work. On the other hand I feel it's good to have a
temp gauge and pressure and voltmeter.

On Wed, Sep 8, 2021 at 7:19 AM Jim Adney <jadney at vwtype3.org> wrote:

> On 7 Sep 2021 at 11:39, William Jahn wrote:
> >  I read that Gene Berg said most of the VDO and other brands of oil temp
> > gauge senders were not accurate in a certain range , and I can't recall
> off
> > hand what the range was. I'm also not sure if he was referring to both
> the
> > gauge and sender combined.
> My recollection is that Berg simply said that all the temp sensors he had
> tested were inaccurate. I'm willing to assume he meant the combination of
> sensor and readout, since nothing else makes sense. I don't recall his
> mentioning any particular range, but the only range you're interested in
> is
> the one that just happens to be around the boiling point of water.
> Gene said this as an introduction of his Beetle dipstick sensor indicator,
> which is just an on/off switch that you wire in parallel to the oil
> pressure
> switch, so it also turns the oil pressure light ON at 212 F. This is quite
> reasonable since that's a good checkable point for oil temp.
> It was this note from Gene that made me realize that this was a good way
> for
> anyone to check the accuracy of their gauge. If you happen to live at high
> altitude, where water boils at lower temps, you may want to drive downhill
> a
> bit to do this test, or find a chart for boiling point of water vs.
> altitude.
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
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