What size pipe thread for pyro probe?


Well-known member
I have a VDO Pyrometer gauge on order but is backordered. I have the exhaust manifold off and wanted to drill and tap the probe hole while its off. The gauge is backordered for an undermined time and I would like to go ahead drill, tap an plug the hole so I can continue the motor reassembly.
Anyone know what size hole it should be? From looking around the net it looks like 1/4npt but not actually having the kit in hand I don't know for sure.
Also my plan was to put the hole in the exhaust manifold between cylinders 1 and 2. Sound good? 200TDI
Thanks much.


Well-known member
its 1/4 NPT, check the German tech doc on VDO's website under downloads. You can see it listed as "R 1/4"

Best location for the probe is directly under the turbo flange. in the area that all 4 exhaust flows merge together. This will get you the most even reading of all cyl and have the best response time on the needle since the flow is much higher in this area.

I recommend a slight upward angle for the end of the probe, so its easy to R&R when the manifold is in place.

Even tho i cut the probe wire and others have, VDO does not want you to cut it. So play it safe and bundle up the extra in the dash