Oil pressure sending unit
 

So I read a few threads here and there about how a 280ZX oem sending unit was more reliable than the oem 300ZX unit for some reason and how the 280 part fits the 300. Either the NOS part I got was not from a 280 or that theory is no Bueno because the plug is completely different. My old one has two vertical prongs, the new one had a vertical and a horizontal prong. Has anyone else tried this? Maybe the part I received isn't as it was advertised?

I can tell you that 3 decades of 300ZX oil pressure experience tells me that Nissan didn't have it right for the Z31 - so they probably didn't have it right through the 280s. In my Z31s the sending unit works fine through maybe a year or so and then the dash gauge reports low pressure at higher rpms. You replace the sending unit with new OEM and it does the same, reporting low after a while as soon as the engine is hot. Makes you crazy. I tried a couple of aftermarket senders and they do the same. Clean oil, new filter regularly and forget about reading true oil pressure on the road. Ain't gonna happen. If the pressure was really as low as the gauge says, you would probably hear the valves chattering. Doesn't happen. Somebody out there may have a solution but I never got any sending units to work right. :120:

Normal oil gauge movement
 

Hey, so quick question on this topic. On an analog dash, how quickly does the dash gauge normally react to changes in oil pressure? My gauge very slowly rises to about 30 psi and just stays right around there regardless of temperature, rpm, or running time. I replaced the sending unit with a cheapo Duralast just to see if it made a difference and it did not. I've seen a digital dash gauge move pretty quickly so just wondering if the analog gauge should be as responsive. If so then I will have to see if i can get a better sending unit.
Thanks.

My sending was doing the very same thing, so I plumbed in a mechanical gauge and found the nominal oil pressure chart at rpm in the factory service manual. My pump and pressure regulator were working correctly, so I replaced the sending unit with a Beck Arnley unit:



The dash gauge has been happy and fairly accurate ever since.

Cool, and thanks for the prompt reply! I did see where someone recommended the Beck/Arnley unit in another post, maybe that was you. Eitherway, thanks for the recommendation.

Actually, I'm not really recommending the Beck Arnley brand, I'm just saying so far it works as well as an OEM for me. There may be other brands that fit and work as well. If the units weren't so damn expensive, I'd normally recommend sticking with a Nissan OEM part.

Good luck with your car.