89TurboII

Hello,
I need some quick help..........I've just completed a JSPEC swap (when my other motor Blew) anyways the question is After the swap I have no oil pressure.......THE question is "I need to know if the gauges ever go bad" the reason I think that my gauge is bad is that it doesn't show any oil pressure(accually if you were to try to read it would read negative pressure(trying to say the needle is below Zero. Does any one know what I mean) the car has be down for 6 weeks so any help would really help me to get the seven on the road.

Thanks, Nick

HAILERS

See if the sending unit has a bare spot on the wire touching ground. If the wire is on the sending unit good, then consider swapping the sending units b/t the two engines. If that is not possible, patch in a manual gauge to see if you have pressuire. If that is not possible, go to Radio Shack and buy a 150 ohm resistor and put one end b/t the wire that goes to the sending unit and the other end to ground. The gauge in the car should read about 55 psi. If that does not work, barely crack a banjo bolt on the oil cooling line and crank the engine. See if your pumping oil. I think the best of the above is to get a cheap manual oil gauge from the auto store and check the pressure that way. I took out he banjo bolt for the lower oil cooler line at the rear housing, and drilled and tapped threads for manual sending unit. You should be able to pull all the plugs and rev the engine using the starter and get 40 plus psi to show on the gauge whether electrical or manual.

Felix Wankel

You can also buy a 6mm (I think) to 3/8'' adapter, and screw the adapter in where the stock oil sender goes, to keep from having to drill and tap a hole in the banjo bolt for a mechanical gauge.

HWO

aftermarket guage is the only way to be sure when looking at oil pressure probs

89TurboII

thanks guys were is the best place to get a manual gauge I've checked autozone but they have nothing that will fit there are a few more places (advance auto, CAR quest,....etc ) hopefully they have them.........one question...........the only way I figured to check was to take out the oil pressure sending unit and crank the motor to see if oil came out when I cranked it so I did that I was under the car and my buddy cranked on the motor and I got covered in oil.......... SO AM I GETTING pressure or is that a crappy way to see. at the time thats the only way I figured to try. please keep the Ideas coming.......thanks so much I'm on my way to work at 5 in the morning so ya'll have a good day and have a happy new year.

LATER,

Nick

Felix Wankel

One other thing, slap your dashboard near the gauges. That always made my spastic volt gauge work

HAILERS

One more......In my above post I mentioned the banjo bolt and how I had drilled and threaded a place for the aftermarket gauge. Well I just checked, and found that the Mazda gauge will screw into that hole in the banjo bolt. Soooo... the size of that hole is 1/8 NPT. The gauge is a SUNPRO that I bought at Pep Boys. That gauge came with a number of unions and adapters, one of which I can say with some certainty will fit in the oil pressure sender hole.

HAILERS

Just a heads up: I just went out to my car and put 142 ohm resistor between the negative terminal and the lead for the oil sender unit(unit out of the picture). I got a guesstimated 40psi instesd of the expected 60psi. I also patched in a 100ohm resistor and instead of getting the expected 110psi reading I got a guesstimated 75 psi. So you can see either the gauge is not so hot or I've got some built in resistance in the connectors that should not be there. There is a section in the free download manual, section on meters, that gives you the expected results if you put a 102ohm(110psi), 141.2ohm(60psi,or 196ohm(30psi)resistor in line with the plug on the sender and a ground.
Another common sense thing that has not been mentioned, is to look for 12v at the plug at the sending unit. Shoulda been number one.

86Rx7GXL

Hey guys i got a problem simalar to his, i just got my j-spec in and instead of 0 showing it goes up to like 120? And ideas?

HAILERS

86RX7GXL......Go to Radio Shack and get a 100 and a 200 ohm resistor(cost is something like a buck for a package of five or six). Take the single wire plug off the sender unit. Get a piece of wire and put an alligator clip on one end and clip that to the sensor lead. On the other end either solder or just clip on the 100ohm resistor and attach the other end of the 100ohm resistor to the neg post on the battery. Turn the key on and wait for the oil gauge to max out. Should be about 110psi. Do the same with the 200ohm resistor. Should read about 30psi. That should give you an idea if its the gauge or the sending unit. If you determine its the sending unit, they can be torn down and adjusted properly. I also suggest buying the Sunpro(cheap) manual gauge and screwing it into the hole where the present sending unit goes, to give you a realistic idea of what your real pressure is. Just a note: You can also get three 50ohm resistors and solder them in series and do the above as stated with the 100 and 200 ohm resistors. I made one like this a couple years ago and due to manufacturing tolerances, when soldered together the final resistance was 142 ohms, or if you will 60psi value. See the http://www.iluvmyrx7.com/Technical_I...ice_manual.htm and the section on METERS to see where I got the values for different psi readings.