Hello,
Im modifying my exaust for the new turbo and I want to add a pyrometer (when I can afford it). Meanwhile Id like to add a fitting for one. Can you tell me what the thread is on the VDO pyrometer sender you purchased?
-Thanks
-Ike Goss

The thermocouple assembly that came with the VDO guage from egauges was a :
Hewitt Industries V1531007177A

My thread guage measures out the part that goes in the bung which is welded into a part of the exhaust as:

18 tpi

the screw in portion is about 9/16" but seems a little smaller than that. It is also smaller than 14mm. It statically measures about .54" at maximum diameter of the threads (which increase from .53 at the end to .54 at the hub).

The part in question is threaded on both sides (one recieves temp sensor(and is much smaller with a different thread pitch and one screws into the exhaust bung).

Here are some picts:

Billster

Here is another:

And the last one:

If you need any other info, let me know.

Billster

Wow, That just what I need. Thanks so much for the fast and very complete response. I owe ya a beer.
-Regards
-Ike

It's 1/4" NPT, that's why you found it measured less at the end and more near the hex. It tapers to provide a good seal. I had to drill a 3/4" hole to weld the bung in place. With a thick enough manifold you can probably drill and tap it for the fitting. Take the turbo off, drill a 7/16 hole, tap it and install. There are some smaller thermocouples out there too that only use a 1/8" NPT fitting.