[T3] 73 T-3 oil temp?

William Jahn willjahn975 at gmail.com
Wed Sep 8 19:53:29 PDT 2021

I am always told SAE 40 is too thick. Would it be wise to try SAE 30? Just
to see what the temps are. Autozone has STP SAE30 detergent oil , no idea
what the zinc content is . I still want to see what the cooler bypass
relief valve looks like. If the spring is weak it may not allow the oil to
go through the cooler. I do have a NOS spring and piston, also want to know
if the relief valve is free and not stuck. It's been there since 97 and I
used the one from the 73 case so that spring has to be pretty old and the
73 did get real hot once over 250.   I understand how thick oil may take
too long to open the path to the cooler. I ran Castrol for a few years. It
has no zinc yet it didn't hurt anything. This engine does not have more
than 40K miles on it . If I go to SAE 30 and it runs cooler and I hear no
noises it might be ok , if I hear noise I can go back to SAE 40.  The
Valvoline SAE 30 costs a lot just to see if 30 makes any difference.

On Wed, Sep 8, 2021 at 10:36 AM William Jahn <willjahn975 at gmail.com> wrote:

> 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
> VW."
>  This is the video I saw talking about the VDO temp gauge sensor in the
> oil cooler bypass spot.
> https://www.youtube.com/watch?v=OBdOMmf1Pho&t=15s.
>  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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