Oil Pressure...
Discussion
Driving home today I noticed the gauge sat at 90psi, no change at idle, no change under load, just sat on the bumpstop at 90psi. 
First guess would be the Oil pressure sender (again) would it be a good first guess to change this first, everything seems ok with the running of the car and it's a few months till service time so could do with sorting it out sooner rather than later.
First guess would be the Oil pressure sender (again) would it be a good first guess to change this first, everything seems ok with the running of the car and it's a few months till service time so could do with sorting it out sooner rather than later.
The oil pressure gauge is electric and the value displayed will be based on the voltage supplied to the gauge from the sender. I don't know whether the gauge would read 0 or 90psi with zero volts (I would suspect 0), but what Spend was trying to point out is that there may be 2 wires touching which makes the gauge read 90 (either to ground - 0v or to the +ve side -12v). Have you noted the reading with the ignition on but without the engine turning ? If it still reads 90psi then it is probably a sender or wiring fault. If it is reading 0 then it may be a relief valve problem and don't run the engine until it is sorted out as too much oil pressure is almost as bad as none at all.
Bob the Planner said:
Have you noted the reading with the ignition on but without the engine turning ? If it still reads 90psi then it is probably a sender or wiring fault.
With ignition on but engine off it's 90.spend said:
If you take the lead off the sensor the gauge should read 0, if you touch it to ground it will read max 
I'm sure you follow that Steve
Yeap thats about my 2 spanner level. Is that with engine on or off though, and what does this actually tell me. I'm sure you follow that Steve 
Will try and get underneath it this afternoon.
d type way....still 90 
Hi I've had a similar fault with mine. Gauge shoots to full scale as soon as you turn the key on.
Removing the sensor wire off the back of the gauge (green with a grey trace on my 94 chim) and the fault was still the same. Earthed out the terminal on the gauge and it reads 0 psi from this I suspect that the wire may be broken or have a poor connection coming from the sensor (or the sensor is fubar).
I will confirm if the sensor is faulty by earthing out the terminal on the sensor and see what happens to the gauge reading.
I will do this tonight and confirm what happens.
Removing the sensor wire off the back of the gauge (green with a grey trace on my 94 chim) and the fault was still the same. Earthed out the terminal on the gauge and it reads 0 psi from this I suspect that the wire may be broken or have a poor connection coming from the sensor (or the sensor is fubar).
I will confirm if the sensor is faulty by earthing out the terminal on the sensor and see what happens to the gauge reading.
I will do this tonight and confirm what happens.
Think I'm going to demote myself to 1 spanner. 
Managed to find the sensor....
Think it should only have one wire going to it
Engine off Ignition off 0
Engine off Ignition on 90
Engine on 90
Wire unplugged ignition on enging off....90
Wire unplugged engine on...still 90
Tried to get a volt reading at the wire and it's either 0 or I'm failing miserably to do anything today, but with a bulb test thingy I found in the tool box it looks like there is power at the end of the cable?
Does this tell me anything interesting?
My guess is the sensor but it'd be nice to be sure, and from memory I think theres a load of different types and the one I want is bound to be the hardest to get hold of.
Managed to find the sensor....
Think it should only have one wire going to it
Engine off Ignition off 0
Engine off Ignition on 90
Engine on 90
Wire unplugged ignition on enging off....90
Wire unplugged engine on...still 90
Tried to get a volt reading at the wire and it's either 0 or I'm failing miserably to do anything today, but with a bulb test thingy I found in the tool box it looks like there is power at the end of the cable?
Does this tell me anything interesting?
My guess is the sensor but it'd be nice to be sure, and from memory I think theres a load of different types and the one I want is bound to be the hardest to get hold of.
Edited by raceboy on Saturday 9th February 14:07
Steve, if you took the wire off the sensor, and then switched the ign on - are you sure the gauge went from 0 to 90 and that the wire you removed wasn't touch anything? That would imply a fault elsewhere from the sensor.
That should only be a very thin wire BTW - it looks like you have had some butchery done from your picture
Dave
That should only be a very thin wire BTW - it looks like you have had some butchery done from your picture
Dave
raceboy said:
Think I'm going to demote myself to 1 spanner.
Managed to find the sensor....
Think it should only have one wire going to it
Engine off Ignition off 0
Engine off Ignition on 90
Engine on 90
Wire unplugged ignition on enging off....90
Wire unplugged engine on...still 90
Tried to get a volt reading at the wire and it's either 0 or I'm failing miserably to do anything today, but with a bulb test thingy I found in the tool box it looks like there is power at the end of the cable?
Does this tell me anything interesting?
My guess is the sensor but it'd be nice to be sure, and from memory I think theres a load of different types and the one I want is bound to be the hardest to get hold of.
Steve .. when I fitted that last time I'm pretty sure i bought two cos 1) theyre unreliable at best and 2) the place i bought them from said they were all-but obsolete .. if you're lucky i might still have the other one on the shelf upstairs .. Managed to find the sensor....
Think it should only have one wire going to it
Engine off Ignition off 0
Engine off Ignition on 90
Engine on 90
Wire unplugged ignition on enging off....90
Wire unplugged engine on...still 90
Tried to get a volt reading at the wire and it's either 0 or I'm failing miserably to do anything today, but with a bulb test thingy I found in the tool box it looks like there is power at the end of the cable?
Does this tell me anything interesting?
My guess is the sensor but it'd be nice to be sure, and from memory I think theres a load of different types and the one I want is bound to be the hardest to get hold of.
Edited by raceboy on Saturday 9th February 14:07
spend said:
That should only be a very thin wire BTW - it looks like you have had some butchery done from your picture
trackcar said:
when I fitted that last time
I'm saying nothing...... trackcar said:
I'm pretty sure i bought two cos 1) theyre unreliable at best and 2) the place i bought them from said they were all-but obsolete .. if you're lucky i might still have the other one on the shelf upstairs ..
You'd be a life saver if you've still got it knocking about mate, let me know if you've still got it and I can pop up to try it, don't mind getting my hands dirty but remember my 1 spanner rating. Just a follow up which looks like its a little late but it may help someone else.
I removed the wire from the pressure sensor ( brown with a green trace at sensor which changes to green with silver trace in loom plug behind dash). With the IGN on the gauge shows full scale. I then put the sensor wire to earth and the gauge went to zero, removed wire from earth gauge shot back to full scale.
From this I think that the sensor's resistence increases with pressure and if the sensor goes open circuit, the gauge reads full scale.
Just to confirm this I then put a meter on the sensor which indeed showed it to be open circuit. So it looks like I might need a new sensor!!!
Hope this helps Ade
I removed the wire from the pressure sensor ( brown with a green trace at sensor which changes to green with silver trace in loom plug behind dash). With the IGN on the gauge shows full scale. I then put the sensor wire to earth and the gauge went to zero, removed wire from earth gauge shot back to full scale.
From this I think that the sensor's resistence increases with pressure and if the sensor goes open circuit, the gauge reads full scale.
Just to confirm this I then put a meter on the sensor which indeed showed it to be open circuit. So it looks like I might need a new sensor!!!
Hope this helps Ade
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