Kryndon
Proven Member
- 944
- 591
- Jan 10, 2014
-
Bulgaria,
Europe
Backstory:
A year ago I suddenly noticed that the stock oil pressure gauge was reading awful low, settling just above the lowest white mark at idle (~750 RPM). At cruise around 2k RPM it was still under the midway mark. So I thought maybe the original sending unit got weak and was reading lower than usual (both balance shafts are deleted and I'm feeding the 16G from the head, so oil pressure should definitely be higher than stock!). I had a spare used 6 bolt sending unit on the shelf so I put that on, but again it was reading exactly the same as the old one. I hadn't really done anything to the car prior to this sudden change.
Fast forward to recently, I switched to 15W-50 for other reasons but also to see how it would affect the pressure; and it didn't. Gauge was showing always under the middle mark and only ever went slightly above it if I was hammering on the car. Also, the needle itself moved fairly slowly. So a few days ago I ordered a Beck&Arnley replacement sending unit (BAR 201-1799) from Rockauto and installed it yesterday. When I started the car up, the needle went to the very top and stood there for the entirety of the warm-up period. I went on a drive and I noticed sometimes it went back down to the lowest mark during idle but then it really quickly moved up as soon as i started revving and accelerating. Now it seems the needle is hovering above the middle mark around 2000 RPM in city driving conditions. The needle is now much more erratic and responsive to RPM changes.
When I compared the OEM unit to the aftermarket one, I noticed the OEM has a pinhole sized entry for the oil to flow through into the sender, whereas the a/m one is noticeably bigger. I'm starting to think that the a/m unit is either faulty or the little hole diameters have an effect on the readings, because if you think about it, a smaller hole will cause the pressure of the oil entering it to rise, and a bigger hole will have less pressure but more flow. So could this be affecting the way the needle on the dash moves? If so, why would companies make replacement sending units with such a design change? I compared to other units and they also seem to have a much bigger hole. I'm also wondering if the pinhole opening on the OEM unit is acting like a filter to make the gauge needle move slower?
At this point I am unsure whether my original 2 OEM sending units were bad or if the new one is OR if I have some weird oil pressure issue (engine was fully rebuilt in 2019 so I'm less inclined to believe it's a mechanical issue). Also the wiring to the sender and switch are in good shape with fresh/clean connectors.
If someone has used the Beck/Arnley oil pressure unit or any other replacement, can you please share how it affected your pressure gauge needle?
A year ago I suddenly noticed that the stock oil pressure gauge was reading awful low, settling just above the lowest white mark at idle (~750 RPM). At cruise around 2k RPM it was still under the midway mark. So I thought maybe the original sending unit got weak and was reading lower than usual (both balance shafts are deleted and I'm feeding the 16G from the head, so oil pressure should definitely be higher than stock!). I had a spare used 6 bolt sending unit on the shelf so I put that on, but again it was reading exactly the same as the old one. I hadn't really done anything to the car prior to this sudden change.
Fast forward to recently, I switched to 15W-50 for other reasons but also to see how it would affect the pressure; and it didn't. Gauge was showing always under the middle mark and only ever went slightly above it if I was hammering on the car. Also, the needle itself moved fairly slowly. So a few days ago I ordered a Beck&Arnley replacement sending unit (BAR 201-1799) from Rockauto and installed it yesterday. When I started the car up, the needle went to the very top and stood there for the entirety of the warm-up period. I went on a drive and I noticed sometimes it went back down to the lowest mark during idle but then it really quickly moved up as soon as i started revving and accelerating. Now it seems the needle is hovering above the middle mark around 2000 RPM in city driving conditions. The needle is now much more erratic and responsive to RPM changes.
When I compared the OEM unit to the aftermarket one, I noticed the OEM has a pinhole sized entry for the oil to flow through into the sender, whereas the a/m one is noticeably bigger. I'm starting to think that the a/m unit is either faulty or the little hole diameters have an effect on the readings, because if you think about it, a smaller hole will cause the pressure of the oil entering it to rise, and a bigger hole will have less pressure but more flow. So could this be affecting the way the needle on the dash moves? If so, why would companies make replacement sending units with such a design change? I compared to other units and they also seem to have a much bigger hole. I'm also wondering if the pinhole opening on the OEM unit is acting like a filter to make the gauge needle move slower?
At this point I am unsure whether my original 2 OEM sending units were bad or if the new one is OR if I have some weird oil pressure issue (engine was fully rebuilt in 2019 so I'm less inclined to believe it's a mechanical issue). Also the wiring to the sender and switch are in good shape with fresh/clean connectors.
If someone has used the Beck/Arnley oil pressure unit or any other replacement, can you please share how it affected your pressure gauge needle?