[T3] 73 T-3 oil temp?

William Jahn willjahn975 at gmail.com
Tue Sep 14 18:36:42 PDT 2021

I realize many don't use gauges. I do yet only so I know if I see the oil
temp or pressure out of the norm.

 I've been doing some reading and since my 73 T-3 is stock there are only 2
places to install an oil temp sensor. One is the sump in place of the drain
plug , the other is the cooler bypass relief. From what I've read many say
there is not much oil flow in the relief port , only what gets past the
piston , the claim is it's reading case heat. The issue with the one in the
drain plug is  the plate from air flow cools the plate  and you get lower
oil readings that is the actual oil temp, plus something was said that
there is not also no oil flow yet in my mind oil is drawn through the

 I recall when I first installed the gauges I got a VDO temp sensor that
fit a T one the oil cooler where the pressure switch normally fits. Well
the temp gauge didn't read until the oil was flowing through the cooler .
When I first got the gauges and they sold me a banjo connector that fit the
oil cooler with one port for oil pressure only and the oil temp sensor for
the sump , I don't even know if they offered the sensor for the relief port
back then.

 I still want to see if the cooler bypass valve is free and may as well
install the new sensor and try both and see.


On Fri, Sep 10, 2021 at 12:03 PM William Jahn <willjahn975 at gmail.com> wrote:

> There is a variation in the relief spring compressed length. 1 3/4"
> 12.3-16 lb. I read that some use a scale and a drill press to compress the
> spring to 1 3/4" and the scale reads the lb . I have a scale and drill
> press.
> On Fri, Sep 10, 2021 at 11:56 AM William Jahn <willjahn975 at gmail.com>
> wrote:
>> I know of Farm and Fleet, they are only in the midwest , I went there
>> when I lived in IL.  It was at least an hour's drive one way. Mainly got
>> batteries for my car there.
>>  As far as oil , all I have in hand is Valvoline SAE 40 , it's not the
>> racing oil , it does have 760 ppm zinc , a bit more than half the amount
>> the VR1 has. I've already used a quart to add to the VR1 because it leaks.
>>  I tried to test the VDO oil temp sensor at 212 F yet the readings were
>> all over the map so that test doesn't help. The only other thing I'd like
>> to do is just check the cooler bypass relief valve. I read quite a bit on
>> it and since the spring it has to be 40 years old because I used the one
>> out of the stock engine. From what I read, if the spring is weak or the
>> valve sticks oil could bypass the cooler . The piston has to be at the top
>> to block the bypass port . I do have 2 NOS springs and one new piston. All
>> I did was use a new piston and the old spring. I don't have any way to
>> check the old spring yet I can compare the uncompressed length with the new
>> one and see how they compare when I compress them by feel. Also fit the new
>> temp sensor that fits the relief valve just to see how it reads and reacts
>> compared to the one I have in the sump
>> On Thu, Sep 9, 2021 at 3:01 PM Jim Adney <jadney at vwtype3.org> wrote:
>>> On 9 Sep 2021 at 11:03, William Jahn wrote:
>>> > Here where I live there exist only 2 auto parts stores AutoZone and
>>> > O'Reilly . AZ mainly carries synthetic oil and as for or any with zinc
>>> > Valvoline 20/50 is it and they have no zinc additives, very little
>>> > conventional oil other than STP in SAE 30 and 40 . O'Reilly has better
>>> > selection trouble is it's in a very bad area.
>>> I think SAE 30 or 40 are probably both fine for you, but 50 is going
>>> overboard. Straight weight oils are hard to find these days, and you
>>> probably
>>> don't need multiweight living where you do. Here in Wisconsin I can get
>>> stuck if I have SAE 40 and the temp suddenly drops to zero. BTDT, don't
>>> want to do it again. OTOH, my Type 3s seldom see those temps any more.
>>> There are often better shopping options than auto parts stores. I buy
>>> store
>>> brand Diesel 15W-40 at a local place called Farm & Fleet. Comes in 2.5
>>> gallon jugs for about $22. There's a chain called Tractor Supply which
>>> you
>>> might find closer. Look for places that sell to truckers. I can find the
>>> Lucas
>>> ZDDP additive at my FLAPS.
>>> --
>>> *******************************
>>> Jim Adney, jadney at vwtype3.org
>>> Madison, Wisconsin, USA
>>> *******************************
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