anyone ever had an incorrect oil sender unit installed?

[BLK95TA]

ever since the shop that did my trans last year broke my oil sender unit, my oil pressure has been flaky. at first i thought it was just all the oil leaks i had and how sometimes the car would be a little low on oil before i had a chance to add more (added over 4 qts in a month)

but now all of that is fixed and i'm still having gauge problems. Could they have installed an incorrect replacement unit?

when the air temp is warmer than about 70 out, once the car warms up, the oil pressuer will be halfway in between the red mark and the first hash mark (20PSI)

but, if i sit at a light for more than a minute or 2, the oil pressure will hit the top of the red zone and the check gauges light will come on. shiftig to neutrol usually makes it go away, but sometimes ive seen it drop to 0 and then jump back up before the light goes off instead of going straight back up. i dont think its an actual oil pressure problem since if it was actually reading 0, and as many times as ive seen that stupid light come on, i'd have major problems by now. and if the temp is below 70 or so, the light never comes on and the gauge never goes into the zone where the light would come on. i'm guessing either the sender unit they put in is bad, or when they broke the other sender unit they might have crimped the wires? and maybe the wires are overheating slightly and showing the incorrect temperature (usually the temp gauge is sligtly over straight up when the light will come on) i'm running 5w30 valvoline currently.

any help is appreciated..

[94zgreenmachine]

A couple of things you could try.
1. Verify the engine does have pressure or at least it is correct. By your oil filter, just a bove it on the block, you will have a 1/4 NPT pipe plug. You can remove it and get a very cheap mechanical gauge. Hook it up and see what it reads.

2. It is possible the tranny shop fubarred some of the wiring when they serviced the tranny. Your 95 should have the sensor on the back rail behind the intake. Try going over the wiring and make sure they didn't cut any of the wiring or that you have any loose connections at the plug/harness.

3. Personally, for me, the GM sensors worked best for me. I had 3 from Autozone that were always off. The sensors would give different reading everytime I swapped them. Bought a GM sensor and have been fine ever since. No experience with ones from Advance or Napa, but I only use the original stuff from that day on.

[BLK95TA]

A couple of things you could try.
1. Verify the engine does have pressure or at least it is correct. By your oil filter, just a bove it on the block, you will have a 1/4 NPT pipe plug. You can remove it and get a very cheap mechanical gauge. Hook it up and see what it reads.

2. It is possible the tranny shop fubarred some of the wiring when they serviced the tranny. Your 95 should have the sensor on the back rail behind the intake. Try going over the wiring and make sure they didn't cut any of the wiring or that you have any loose connections at the plug/harness.

3. Personally, for me, the GM sensors worked best for me. I had 3 from Autozone that were always off. The sensors would give different reading everytime I swapped them. Bought a GM sensor and have been fine ever since. No experience with ones from Advance or Napa, but I only use the original stuff from that day on.


with as much trouble as the guys had changing that oil sending unit (seemed like it took them about 45 minutes of struggling with it) i would probably have a hard time getting it out...maybe i should have someone hook it up to a sensor at a shop (is there an easier place to hook up a gauge? so i can see it from in the car? the problem doesnt really manifest itself when the car is in Park) and i dont know if they used a GM part or not, my guess is no, although IIRC the damn thing was $45

[Fixxer99TA]

A couple of things you could try.
1. Verify the engine does have pressure or at least it is correct. By your oil filter, just a bove it on the block, you will have a 1/4 NPT pipe plug. You can remove it and get a very cheap mechanical gauge. Hook it up and see what it reads.

2. It is possible the tranny shop fubarred some of the wiring when they serviced the tranny. Your 95 should have the sensor on the back rail behind the intake. Try going over the wiring and make sure they didn't cut any of the wiring or that you have any loose connections at the plug/harness.

3. Personally, for me, the GM sensors worked best for me. I had 3 from Autozone that were always off. The sensors would give different reading everytime I swapped them. Bought a GM sensor and have been fine ever since. No experience with ones from Advance or Napa, but I only use the original stuff from that day on.

Follow this advice each step until you find what your problem is. I also would not be installing (or allowing anyone else to install for that matter) anything but GM parts for replacement sensors. Too much garbage electronics being sold by Autozone and the rest these days, too much to ignore.

Changing the oil pressure sender is one of the easiest jobs you can ever do on an LT1, try it and you will see what I mean. The hardest part will literally be jacking the car up :D

[BLK95TA]

Follow this advice each step until you find what your problem is. I also would not be installing (or allowing anyone else to install for that matter) anything but GM parts for replacement sensors. Too much garbage electronics being sold by Autozone and the rest these days, too much to ignore.

Changing the oil pressure sender is one of the easiest jobs you can ever do on an LT1, try it and you will see what I mean. The hardest part will literally be jacking the car up :D

jacking the car up? IIRC they had the car on a lift, on the ground and the guy was trying to get to it from the top, and had to try several different tools to get to it

maybe i'm thinking of a different part? the one on the back of the engine that shows the oil pressure on the gauge.