ken99

I've been a forum member for some months, but just recently obtained an 86 NA 300ZX. I've been a gear head most of my life and once owned a Maxima with the VG30E engine. The car was running when parked 7 years ago, but hasn't turned a wheel since. I put a lot of prep into the engine before I tried starting it, including new fluids front to back. The engine did start and ran smooth after only 10 to 15 seconds on the starter. Oil pressure initially was quite strong (30+ psi) but then dropped off to ~10 psi at idle as the engine warmed up. The FSM (yes, I have a copy) indicates minimum oil pressure should be 11 psi at idle. Truth is I find the gauge difficult to read at the low end of the scale and I wish to make sure I don't have oil pump issues. I have a manual gauge I wish to plumb into the oil system. FSM says to remove the oil pressure sensor to screw in the gauge. My question, is there easier access to the pressurized oil galley somewhere else on the block? I am finding access to lower sides of the block is much more cramped than the east-west installation in the Maxima.

Thanks for any feedback I get.

Ken

rogerz

unlikely it is a bad oil pump. the z31 gages are notoriously inaccurate. try a new sender or put a mechanical gage in there to get an accurate reading. best bet would be a 4-5 inch 1/8 inch pipe nipple. Might be 1/4 inch. the Japs use BSP thread but close enough to work with NPT in those sizes. you can get a nice electric gage from Harbor Freight for around $20. thread right into the hole but you have to run wires and figure out where to mount the gage. I forget the gages that come standard with the na because mine was a turbo GLL. If you pull the radio the gage module is held up with three screws and comes right out. sacrifice one of those and the HaRBOR Freight gage fits right in there. If there were some way to post pics on this forum I could shoot you a pic but I have never figured out how to post a pic even following the directions in the FAQ. I put in a boost gage and a fuel pressure gage and they look like a factory install. plus you get seven different color schemes. I checked the pressure gage with my air compressor and a known good mechanical gage. it checked out within a pound.

ken99

Manual pressure gauge says the pump is working as designed. 11-12 psi @ idle @ operating temperature, ~70 psi @ 4000 RPM. I guess a new sending unit is next. BTW, my thread gauge says the nipple on the old unit is 1/8" NPT. A brass NPT fitting worked perfect for connecting the pressure gauge. Of coarse my thread gauge isn't designed to work with British Standard Pipe fittings, so I have no idea how far apart the two standards are. At least the car has a negative ground....