Does the VDO CHT Gauge use a K or J-Type Thermocouple? Options

[frank_c]

As the title states, I'm trying to determine if the VDO CHT Gauge uses K or J-Type Thermocouple (TC).

Backstory:
My '76 2.0 has a VDO CHT gauge installed by a PO (photo 1). I know there are better options out there, and I plan to replace it with something better the next time I drop the engine, but for now my main goal is to to get the VDO back to a functional state.

The PO installed the thermocouple at the stock temp sensor location @Cyl #3 on the 2.0 head. In addition, the "Cold Junction" for the TC wiring was in the engine bay near the distributor. So, in an effort to provide a more accurate temperature reading, when I had the engine out last winter, I:

1. Replaced the old TC with a K-Type TC located under the #3 spark plug (photo 2)
2. Used a special K-Type connector in the engine bay and extended the K-Type TC wire all the way to the gauge (cold junction at gauge).

The gauge needle did not move upon my initial test.

To ensure the gauge was still good, I hooked it up directly to the old TC that I removed and heated the TC with a heat gun. The needle moved after I swapped +/-.

I then re-connected the new TC wire I ran, this time swapping the +/- terminals, started the engine and confirmed that after a few minutes the needle moved (yay).

Apparently, per the below Samba thread, some VDO CHT gauges have their +/- terminals swapped, so that solves that mystery:

https://www.thesamba.com/vw/forum/archive/i...t-173868--.html

But I noticed something else during this process which is why I'm asking about the TC type. I purchased K-type TC and wiring because what I read up until that point indicated the the VDO gauge used a K-Type TC. The K-Type TC wiring is color coded Yellow(+) and Red(-) [ see chart below]. However the wiring on the old TC I removed is Red(ish)/White. And according to the TC color chart, Red/White is a J-Type TC. To confirm, I checked and found that the White(+) lead of the TC I removed is indeed magnetic. I then found this thread on Shop Talk Forums stating that the VDO CHT actually uses a J-Type TC, not a K-Type as most commonly thought:

https://shoptalkforums.com/viewtopic.php?t=144947

If it turns out that the VDO gauge does indeed use a J-Type TC, then since I already have the K-Type TC, connector, and wiring installed, the easiest path forward for me is to simply purchase a K-Type gauge (which may pose a new challenge). If it uses a K-Type, then I should be good for now.

Sorry for the long post. Looking forward to hear what folks have to say who have been down this path already.

[Montreal914]

More countries chart.




For the gauge there is also this cost effective option.

https://thesensorconnection.com/products/ch...eter-gauge-kits