[DeTomaso] Water temp gauge update

[Steven Edwards1969Dart]

Thanks for all the replies.

I will try to answer some of the questions

The engine is an aftermarket; all aluminum Fontana Block, C302 heads. There is not thermostat boss, the heads are tapped ¾” npt, both heads are connected to a remote thermostat housing, which has provisions for a mechanical temp probe and the EFI temp sending unit.
The car came with the stock Veglia gauge sending unit in the tank, it worked for over 30 years that I know of. 
The new sending unit did not have continuity from the base to the stud, which it is suppose to until it warms to operating temp.
As for Teflon tape. I do not use the tape, I used a small dab of paste, then take my figure to spread it onto the threads, a little goes a long way. 

As for the sending unit as a idiot light, which is possible, put in wrong box. My thought are the light and the gauge sending unit should work the same function. The light is off or on, should be open when cold then close when hot, where the gauge is open when cold, giving a variable ground as it gets hot. They are not interchangeable, but should be open then cold. I maybe wrong on this function, but it should be a grounding circuit. 

I just did a separate wire test, ran a wire from the gauge to the sending unit, turned on the key and the gauge went to max. So my thoughts are the sending unit is the cause. I have a new sending unit coming, will try that. I am confused as to why it is grounded thru the wire, but the meter continuity test shows it open between the base and stud. Very strange. 

Steven Edwards

-------------- next part --------------
   Thanks for all the replies.


   I will try to answer some of the questions


   The engine is an aftermarket; all aluminum Fontana Block, C302 heads.
   There is not thermostat boss, the heads are tapped 3/4" npt, both heads
   are connected to a remote thermostat housing, which has provisions for
   a mechanical temp probe and the EFI temp sending unit.

   The car came with the stock Veglia gauge sending unit in the tank, it
   worked for over 30 years that I know of.

   The new sending unit did not have continuity from the base to the stud,
   which it is suppose to until it warms to operating temp.

   As for Teflon tape. I do not use the tape, I used a small dab of paste,
   then take my figure to spread it onto the threads, a little goes a long
   way.


   As for the sending unit as a idiot light, which is possible, put in
   wrong box. My thought are the light and the gauge sending unit should
   work the same function. The light is off or on, should be open when
   cold then close when hot, where the gauge is open when cold, giving a
   variable ground as it gets hot. They are not interchangeable, but
   should be open then cold. I maybe wrong on this function, but it should
   be a grounding circuit.


   I just did a separate wire test, ran a wire from the gauge to the
   sending unit, turned on the key and the gauge went to max. So my
   thoughts are the sending unit is the cause. I have a new sending unit
   coming, will try that. I am confused as to why it is grounded thru the
   wire, but the meter continuity test shows it open between the base and
   stud. Very strange.


   Steven Edwards