Find This Thermostat

For reference, the thermostat on the left is a normal Stant Superstat #45359 (195°) purchased in 2001. The other two were purchased and used in the mid 1980s. All of them are normal reverse poppet thermostats with a 3/8" stroke, and are specified for use on the small block Chevy, small block Ford and therefore fit the Triumph Tr6.

The Stant uses a 1 1/8" throat (and valve disk) just like virtually every other thermostat you can find today. The other two have 1 1/4" throat. Empirically, I have noticed that the 1 1/4" throat thermostats flow better than 1 1/8" throats, which is exactly what you would expect. For cars designed in Detroit for use in traffic jams in Arizona, this is meaningless. For cars designed in Blackpool with engines from Coventry and designed for the burning hot British summer, the extra flow makes a BIG difference. The center themostat is made by Wahler in Germany. The unidentified one on the right was the best flowing thermostat I ever found.

The thermostat in the Triumph engine sits in a cylindrical cavity. Water must flow up and past the valve disk before passing through the throat during the voyage to the radiator. As you make the disk larger, you decrease the area available for water to pass around the valve. Some quick calculations indicate that the point of maximum flow is a disk size of 1 1/4".

Now Stant has a "wide throat" family of thermostats. The only reverse poppet unit is for the Subaru Impreza, #14147. It has a valve disk of 1 9/16", which is so large it constricts flow around the valve so we loose more than we can gain. If the chamber was bigger, we could use it, but I believe the chamber walls are not thick enough to take the amount of grinding required.

The one on the right is labeled "160" and "PGO" on the bottom of the bulb. These may have been purchased at Sears around 1983. I've checked Sears and haven't found anything like them.

Several people have told me where to find the Wahler themostats. I haven't updated ths page recently as I was planning to test the Wahler units and report on how they performed to. I haven't mannaged to do this in two years! The most recent detective was Chris O'Connell:
Wahler website:
They also show a US based sales contact rep with the following info:
Sales agency USA
Wahler Automotive Systems, Inc.
32427 Schoolcraft
Livonia, MI 48150
Phone: +1 734 522 1013
Fax: +1 734 522 7214

Prior detectives were John Questel and
Hayden Olenik
Hayden found

The Wahler themostats were identified as # 3004.74 (74 degrees C) and # 3004.82 (82 degrees C).

I apologize to everyone for not acting on this information sooner.

If you know where to find the right hand thermostat, let me know at CRC

I've tried the Rober Shaw/Mr Gasket High Flow thermostat with three ports. When they work, the snap action high flow/no flow seems to improve cooling. However, these seem to use water pressure to open the valve; The Tr6 water pump is so gutless that sometimes the valve jams shut. I've tried two with the same result. Hans Beijner reports that they work fine in his 3000M.

Robert Shaw/Mr Gasket High Performance Thermostat.
Works in the 3000M but not the 2500M.


Last updated on October 11, 2005.