Rally gauge oil pressure

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IdleWanderlust

Not-quite-so-new-guy
Sep 19, 2022
18
11
3
Hey Everyone,

My oil pressure gauge swings wildly back and forth at idle and low rpm. While driving however it holds steady at just above 30. I’m thinking it maybe a vacuum leak but could it also be normal? Temp gauge stays steady and just below 220 once warmed up and doesn’t change with driving.
 

DB87442

Apprentice
Nov 27, 2021
88
165
33
Cartersville, GA
Hey Everyone,

My oil pressure gauge swings wildly back and forth at idle and low rpm. While driving however it holds steady at just above 30. I’m thinking it maybe a vacuum leak but could it also be normal? Temp gauge stays steady and just below 220 once warmed up and doesn’t change with driving.
Mine does the same thing and so does the speedometer (though not a wild). Hopefully someone will chime in with some ideas on a fix!
 
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IdleWanderlust

Not-quite-so-new-guy
Sep 19, 2022
18
11
3
Mine does the same thing and so does the speedometer (though not a wild). Hopefully someone will chime in with some ideas on a fix!
I’m thinking it might be the wrong pressure sensor installed. There are two types one for the dummy light dash and one for the rally gauges. I ordered a 60psi pressure sensor and when it arrives I’ll let you know if it made a difference.
 

78Delta88

Royal Smart Person
Supporting Member
May 23, 2022
1,183
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904
113
SW Arizona
Mine does the same thing and so does the speedometer (though not a wild). Hopefully someone will chime in with some ideas on a fix!
If you are running the OEM, Just replace the sender. Sounds like the wiper or resistor is worn out, dirty or both. Could also be dirt build up in the line drilled in the block that feeds the sensor.
 
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78Delta88

Royal Smart Person
Supporting Member
May 23, 2022
1,183
1
904
113
SW Arizona
On the Speedo cable it just needs greased. But easier to just replace. If you have the split cable that comes with the speed control, you can try the short cable first.

Doing dash work isn't difficult, just takes some extra finesse plus remember you are working with 40 year old plastic pieces that used to love to break back when car was still on warranty.

The tool to grease Speedo cable might still be available, not sure. The old method was to remove the cable at the transmission and using tool pump grease into the sheath. It's a specific type similar to the spray can lithium.
 
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DB87442

Apprentice
Nov 27, 2021
88
165
33
Cartersville, GA
I’m thinking it might be the wrong pressure sensor installed. There are two types one for the dummy light dash and one for the rally gauges. I ordered a 60psi pressure sensor and when it arrives I’ll let you know if it made a difference.
Good catch... let me know if the other one works.
 

gdouaire

G-Body Guru
Supporting Member
Aug 7, 2013
626
439
63
Québec City, Québec CANADA
The oil sender for the rallye gauge (top) is much bigger than the one for the idiot light (bottom).
download (2).jpeg


ado-c8020_jp_xl.jpg
 
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