Ground locations for Oil Pressure Sender & Pressure Gauge?

[mthomas58]

My oil pressure sender is pegged at 5, even when the ignition is off. I have cleaned the connection on the sending unit and would like to do the same with the ground(s). The gauge worked fine prior to my engine swap (3.2 to 3.2). After the swap, the gauge has been pegged at 5.

[sc_rufctr]

Sounds like your gauge is faulty.... All you can do is check the wiring...

The "sender' is ground to the engine. So you only need to make sure the wire is connected and not faulty.

Mine sender was a bit flaky and sometimes the gauge would stick in one spot. So I removed it and soaked it in acrylic thinners for a while and managed to get some gunk out of it. Try to keep the thinners away from the plastic insulation at the top of the sender.

I opened up the whole a little bit with a small drill bit to help get the gunk. It works really well now ~ Fast reaction to oil pressure fluctuations. I don't mind the needle jumping around a little bit more than stock. I'm confident the gauge is still accurate as all I did was open up the hole by about 50%. If you think about my mod it won't affect the pressure reading just the reaction time.

[mthomas58]

Originally Posted by sc_rufctr

Sounds like your gauge is faulty.... All you can do is check the wiring...

The "sender' is ground to the engine. So you only need to make sure the wire is connected and not faulty.

Mine sender was a bit flaky and sometimes the gauge would stick in one spot. So I removed it and soaked it in acrylic thinners for a while and managed to get some gunk out of it. Try to keep the thinners away from the plastic insulation at the top of the sender.

I opened up the whole a little bit with a small drill bit to help get the gunk. It works really well now ~ Fast reaction to oil pressure fluctuations. I don't mind the needle jumping around a little bit more than stock. I'm confident the gauge is still accurate as all I did was open up the hole by about 50%. If you think about my mod it won't affect the pressure reading just the reaction time.

Thanks for the reply. Been doing some seaching and ran across this thread that suggests the sender is faulty. I'm thinking its the sender rather than the gauge on the basis of the gauge working prior to the swap (same gauge different sender)

Pegged Oil Pressure Reading?

[scarceller]

The gauge will peg if the wire is not connected to the sender, this could mean somehow the wire from the gauge back to the sender has been cut.

Also, I'm rather certain that if you pull the wire from the sender and ground the wire the gauge goes to '0'. You could try this test to see if the wiring is good.

Wire to ground = gauge at '0'
Wire open circuit = pegged gauge.

If I get a moment I'll try this in my car to be sure I recall this correctly.

[JJ 911SC]

Originally Posted by mthomas58

Thanks for the reply. Been doing some seaching and ran across this thread that suggests the sender is faulty. I'm thinking its the sender rather than the gauge on the basis of the gauge working prior to the swap (same gauge different sender)

Pegged Oil Pressure Reading?

Agree, it got to be your sender unit as this is new factor in the equation.

[ecostellodo]

Is the gauge matched to the proper sender? 5 bar to 5 bar?

[RWebb]

may be a gnd on the gauge - check that

think I recall one on my '73

[mthomas58]

Originally Posted by ecostellodo

Is the gauge matched to the proper sender? 5 bar to 5 bar?

Well, that's why I stated 3.2 to 3.2 swap....HOWEVER I guess I shouldn't assume that the replacement motor had the correct sender on it.

[PcarPhil]

Originally Posted by mthomas58

Well, that's why I stated 3.2 to 3.2 swap....HOWEVER I guess I shouldn't assume that the replacement motor had the correct sending on it.

It should have, especially since it was an '87 3.2 to '87 3.2 swap. However do you have a numeric gauge or non-numeric gauge? That makes a difference.

Do you still have your old sender? If so try swapping in your old sender and see if it makes a difference.

[mthomas58]

Originally Posted by Kaefer

It should have, especially since it was an '87 3.2 to '87 3.2 swap. However do you have a numeric gauge or non-numeric gauge? That makes a difference.

Do you still have your old sender? If so try swapping in your old sender and see if it makes a difference.

Thanks Scott. I'll probably order a new one since my old sender yielded a "bouncy" needle....but I could certainly use it to troubleshoot the problem.

[mthomas58]

Just ran a quick test. Gauge pegged at 5 with car off. Pulled sender wire, inserted jumper wire and grounded it to chassis - no change in gauge reading - still pegged at 5. Turned key to on position and needle pegged to zero. Key to off position - gauge remained pegged a zero. Reconnected sender wire - gauge remained pegged at zero. Key to on position and gauge pegged at 5 again. Tested twice - same results.

[sc_rufctr]

After that I would be checking the sender...

It's probably stuck (on the inside) like mine was.

[MT930]

Needle Pegs when the sender fails or the wire is off the sender.
They can be replaced with out dropping the engine.

Stock up on some patience for that swap though.


Pegged Oil Pressure Reading?

[JJ 911SC]

Originally Posted by mthomas58

Just ran a quick test. Gauge pegged at 5 with car off. Pulled sender wire, inserted jumper wire and grounded it to chassis - no change in gauge reading - still pegged at 5. Turned key to on position and needle pegged to zero. Key to off position - gauge remained pegged a zero. Reconnected sender wire - gauge remained pegged at zero. Key to on position and gauge pegged at 5 again. Tested twice - same results.

This should not be this complicated...

Are you saying Just ran a quick test. Gauge pegged at 5 with car off. with out the key in... If that is so there is something really definitely wrong.

With the key in the last position before starting the motor, the needle should be at Zero, If it's at 5 Bar there is something wrong.

Take the connector off and ground it, it goes to Zero, the sending unit is F*ck...