Ah, now I see. I've definitely never run into one of those Monotestor ports. I'd almost certainly have remembered that tab on the valve cover nut as well as a mystery connector. Either that or I've had an unkown TIA in the Volvo Cortex portion of my brain.

Where the sensor is down behind the trans cooler lines is a bit out of sight, so if someone had hacked off the wire at the sensor that might not get noticed, but if I'd seen a cut wire I'd have investigated what it was for. I'm now vaguely recalling a square headed plug in the block back below the drain cock that I used to wonder about. I remember thinking it was some kind of extra drain plug or a freeze plug. I'm thinking my engines may have had a factory plug there.

I'm starting to wonder if it was market dependent whether or not there was a Monotester port.

For example, if dealer service in a country such as Canada, which was a sub-market and separate from Volvo North America with its own head office, plant and parts chain, then they may have saved a couple of bucks by not including the port and not needing to equip all the dealers with Monotestors which I'm sure were grossly expensive for what they were. We had dozens of small Volvo dealers scattered across the country until Volvo Canada did a major consolidation starting back in the late 1980s and closed all the smaller dealers. That's where many of our best indie shops came from as they had factory training plus old stock on parts shelves. Vancouver alone still has five Volvo dealers. There wasn't much extra it could tell an average mechanic, mostly just a convenience port.

Another possibility is it had something to do with the assembly plant whether you got one. Depending on the years and demand for a certain model or trim level, plus the availability of production parts, cars in Canada normally came out of the Halifax assembly plant with the engines shipped over in crates more or less ready to drop in with all the needed harnesses included. Cars destined for the US market often came from Sweden except only certain models and trims levels in certain years where Halifax had the needed production capacity. That sensor and port are a bit exposed for shipping and handling. Mine have all been Halifax cars right back to my '66 122S badged as the Sport Canadian model. Canadian models got what was called the winter package as standard. There were only a couple of years where both 240 and 740s came out of Halifax during what were called the production changeover years. For example, we might go through a period in the early '80s when all 240 DL wagons (which were in high demand) plus all the new 740s came from Sweden. Models like 780s (the OPs car) and the 262C Bertone Coupes always came from Sweden.

Those are my best guesses. Next time I'm in my Volvo indie yard I'll ask what they know about that sensor. In the meantime I'm sure they'll be a variety of comments here about people who have or not had that port.

And yes Art, I realize it has nothing to do with K-Jet/LH-Jet or the EZ ignition systems. It was just mention of 1984 on the UK Club site that made me wonder as introduction of the B230F with LH-Jet was about the only thing special about that year. I'll see if I can come up with some Volvo trivia to test you. Enough of these questions and we can make a Volvo Dementia Test for other old-timers to use.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now