Does this help?

https://www.perfprotech.com/mercury-...1?umodel=17970

I would like to know things like can I put an oil temp sender in place of #7, how about oil pressure gauge there. Is that (#7) before or after cooler.
The choke sending unit, can I put oil temp or pressure gauge/senders here. Why do you control the choke here? How do I test the thermostat operation on the unit?
Thank you.

Crickets?

Wow, I was expecting a wealth of info from the pros here on OSO.

Curious about this as well...

I’ve got no idea. I was hoping then diagram would be helpful. I have not had my hands on one to look at it.

Regarding senders, I would think you could monitor oil temp though pressure I think I’d rather get from the block. Isn’t a temp reading of what’s in the pan a better way to go anyway?

You might need to find one and do some experimenting.

Maybe Mike Mello could chime in? I’m sure he’s got a couple in his stockpile of parts.

Not sure if this helpful, but on my 99 HP 500 the oil temp sensor is factory located above the original filter pad on the block and oil pressure is to the left in the block. The low oil pressure alarm sensor is on the pan rail near it. Also I have been told is the factory location of the oil temp sensor is after the cooler. The only thing screwed into the oil filter adapter from the factory on mine was the switch for the electric choke. I assume this was for ease of installation or maybe stall the motor with the choke if loss of oil pressure? I don't think I would use that port to install a oil pressure gauge due to the oil filter bypass in the adapter. As for oil filter I use the standard Wix 51060 with the check valve. If someone wants particular pics of mine I can try to get them. Not sure how helpful they will be as mine is tight with silent choice exhaust.

Thank you, that is helpful info. What is the large fitting (3/8"?) that looks like a plug on the side of the adaptor? any idea.

Not sure I'll try to go look tonight and snap a couple pics.

https://cimg6.ibsrv.net/gimg/www.off...010bdca4f.jpeg
The fitting on top looks like 1/2 in NPT and I assume is factory plugged. These two by the Choke pressure switch go straight to the oil cooler. I also realized my oil pressure sensor in in the pan rail too via an adapter next to the oil pressure alarm
https://cimg9.ibsrv.net/gimg/www.off...f24e06e97.jpeg
https://cimg2.ibsrv.net/gimg/www.off...b924cc463.jpeg
https://cimg6.ibsrv.net/gimg/www.off...475a3bf83.jpeg
These were the best i could get with low light. The lines run straight down in the same order to the block adapter from the filter housing and don’t cross.