I picked up an '84 GS a few months ago that runs/drives but has been in storage and off the road for a few years. Car needs some carb and brake work which I've slowly been working on this winter while I'm storing it.

The other day when it was warm enough outside to open my garage door, I decided to fire up the engine and let it idle since I hadn't started the car since I parked it in the garage in November. Engine fired up with a spray of starter fluid and idled fine at about 1100 rpm. Let it run for about 10-15 minutes until it came up to temp. I revved it a few times once the engine got warm and noticed that the oil pressure seemed to be reading low. Stock gauge was showing about 15psi at 1100 and actually seemed to drop just slightly when I revved to 3000/3500.

I've searched through the forum archives and it's lead to more confusion than solid answers as to what the issue might be. It looks like it could be anything from a bad oil pressure sending unit to serious engine problems. I checked the oil level and it was a little low but still within in the safe zone on the dipstick. Other than the low pressure reading on the gauge, the engine seemed to run fine.

I'm not sure where to start with diagnosing the problem. Could someone give me some suggestions of what to check starting with the most likely culprit?

Also noticed after I shut the engine off that there was some smoke/steam coming from the air filter and exhaust side of the engine. I think this probably means I have the leaky o-ring issue on the intake coolant passages, but should probably mention it in case this is related to the oil pressure issue.

 

the only way to know for sure what your oil pressure if is to buy/borrow a mechanical pressure gauge and hook it up and see what the results are. The stock gauges on all series of rx7 are not very accurate, even moreso for FB and FC as they are almost, or already over 30 year old electronics

 

After performing a pressure test this weekend with a mechanical gauge, the oil pressure seems fine. However, I did notice that the OMP seems to have a very slight leak. The front cover is covered with a thin layer oil and grime.. The plastic lines don't appear to be cracked or leaking, so it seems to be the gasket between the pump and the engine. I'll have to either replace, rebuild or delete it at some point.

 

I'd leave it as "some point" unless the leak gets horrible. If you try and fix it, there's a very high chance you will make it worse than it was, and then you'll be going down the rabbit hole lol

 

Good point! It looks like it's been leaking for awhile. It's not terrible, just enough to collect dirt and make a mess of the front cover. Also explains the line of grime across the underside of the hood right above the fan. I've got plenty of other things to take care of, so this will go on the back burner. I'll address it if it gets worse or if I need to take the engine out for any reason.