Something isnt rigjt...
Something isnt rigjt... 94z28, newer 383 with mabey 2k on the clock.
I noticed today that the oil pressure was sitting at the first mark from zero. When revved, the guage does not move. On tyhe highway OR when free revving. No weird noises at all. When you turn the car off, the guage stays put, until you turn the car off again. When the key is turned to run, it drops to zero. Aftsr starting, the guage gies right back to that first mark and stays there. Sound like the sending unit is bad?
I noticed today that the oil pressure was sitting at the first mark from zero. When revved, the guage does not move. On tyhe highway OR when free revving. No weird noises at all. When you turn the car off, the guage stays put, until you turn the car off again. When the key is turned to run, it drops to zero. Aftsr starting, the guage gies right back to that first mark and stays there. Sound like the sending unit is bad?
I would love to put a manual gauge on it, but I don't have access to one. I'll try disconnecting the plug on it.
When I turn the key to "run" right now, the gauge zeros itself out. I also noticed that it take about 3-4 seconds for the gauge to register pressure. It always goes directly to 20 PSI though.
Prior to me noticing this, the cold startup pressure was always between the middle mark and the 3/4 mark on the gauge, and would settle down to about halfway between the 1/4 and 1/2 mark when hot. And when revved, it would always increase oil pressure.
When I turn the key to "run" right now, the gauge zeros itself out. I also noticed that it take about 3-4 seconds for the gauge to register pressure. It always goes directly to 20 PSI though.
Prior to me noticing this, the cold startup pressure was always between the middle mark and the 3/4 mark on the gauge, and would settle down to about halfway between the 1/4 and 1/2 mark when hot. And when revved, it would always increase oil pressure.
Update. Sensor disconnected, gauge pegs. It HAD a sensor that I think was wrong. 1/4 inch thread, and a longer shank. It was put in with an incorrect brass elbow piece at the top of the motor. Now, i used a male 1/4 inch to a female 1/8 inch adapter to thread the 1994 sensor (1/4 thread, short shank) in. Turn the car on, now Zero oil pressure. New sensor too. I broke the old sensor taking it off...... So tjats not going back on. Any ideas here? With the sensor out, oil pumps out of the elbow. The elbow was just hand tight......mabey that was it? Im at a loss here.
Here are some pictures of the sensors:
Sensor that came off the car:
New sensor:
New on left, old on right:
same connector.....
old on left (broken) new on right One on the left is 1/4 inch, the one on the right is 1/8 inch.
The non/stock brass fitting I cant get but hand tight, with the small 1/4 to 1/8 adapter
What the hell? Could it not have been registering pressure because the fitting wasnt sealed tight?
Sensor that came off the car:
New sensor:
New on left, old on right:
same connector.....
old on left (broken) new on right One on the left is 1/4 inch, the one on the right is 1/8 inch.
The non/stock brass fitting I cant get but hand tight, with the small 1/4 to 1/8 adapter
What the hell? Could it not have been registering pressure because the fitting wasnt sealed tight?
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TECH Veteran
Joined: Dec 2008
Posts: 4,144
Likes: 61
From: Little Rock, AR
This is what is should have, if it is a late 94 with the sensor behind the intake.
http://shbox.com/1/oil_pressure_sensor.jpg
The sensor with the bigger threads is what is used on an early 94 that had the sensor by the oil filter.
http://shbox.com/1/oil_pressure_sensor.jpg
The sensor with the bigger threads is what is used on an early 94 that had the sensor by the oil filter.
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Verdad Gallardo So... I have tbe correct new senzor then. I just need a pair of 90 degree fittings tbat will work. Coud the fitting not being tight have dropped my oil pressure to zero? Or is it possible i have a dud sensor?
If the fitting was loose you'd be spraying oil everywhere.
This is why you need to pick up a manual gauge and check the actual pressure before you do irreparable damage to the bottom end! A manual gauge is cheaper than replacing the sending unit.
This is why you need to pick up a manual gauge and check the actual pressure before you do irreparable damage to the bottom end! A manual gauge is cheaper than replacing the sending unit.
I'll be picking up a cheap harbor freight oil pressure tester today. Its the only one that was cheap... most others ive found were in the 130-175 dollar range. I'll also be picking up a new sensor again.
Its strange. I started it up as soon as I got home last night, and it read 20 PSI steady, would not move if revved. I removed the drivers side valve cover, removed the sender and the elbow, put the adapter in the elbow, put it back in the car and put the new sender on it. Viola, ZERO oil pressure, and the check guages light on. Thats the only thing that was messed with.... the car hasn't even moved.
I'm guessing I got a dud sensor..... but I'm in a bit of a panic at the moment. With the elbow in, and sensor out, I had the wife turn the car on and it pumped a bunch of oil out of the fitting.... and the strange thing is that the engine is not makingn any noise like it wasn't getting oil...no rattles or knocks. While running, oil dribbles out over the top of the rockers, and when revved a little, it splatters pretty good all over the place.
I'll test tonite..... any guesses as to what it is?
Its strange. I started it up as soon as I got home last night, and it read 20 PSI steady, would not move if revved. I removed the drivers side valve cover, removed the sender and the elbow, put the adapter in the elbow, put it back in the car and put the new sender on it. Viola, ZERO oil pressure, and the check guages light on. Thats the only thing that was messed with.... the car hasn't even moved.
I'm guessing I got a dud sensor..... but I'm in a bit of a panic at the moment. With the elbow in, and sensor out, I had the wife turn the car on and it pumped a bunch of oil out of the fitting.... and the strange thing is that the engine is not makingn any noise like it wasn't getting oil...no rattles or knocks. While running, oil dribbles out over the top of the rockers, and when revved a little, it splatters pretty good all over the place.
I'll test tonite..... any guesses as to what it is?
Thanks guys. I'm picking up the pressure tester at lunch and a new AC Delco sending unit. I'm also going to pick up some brass fittings that will be easier to tighten at teh top of the engine. The one pictured above doesnt get very tight at all, and makes the oil sending unit a pain in the *** to work with. I really need 2 90 degree fittings to make it work properly. I broke off the old sensor when taking it out.. 
Yeah, I have it. The problem was that the fitting i have didnt space the sensor out far enough, and the longer sensor made it next to impossible to take it out straight......so it broke off.
