Bit of a long shot question:

[911hillclimber]

The oil pressure sender on my 1985 3.2 I think has failed. I have a new one somehow with a part number for the 1984/89 3.2 engine.
However, getting the old (original) one off the engine will be hard going. Does anyone have a sender on the 'bench' who can measure the diameter of the thread on the sender please before I fight to get the original off?
I want to know if the new one i have has the correct thread.

I've tried to remove the original sender before and it would not budge.

[jb]

How do you know that it is broken?

[911hillclimber]

Not sure until tomorrow morning JB.
Just assuming the worse!
If the wire from sensor to gauge is continuous then it is this sender.
Have had this situation before about 4 years ago, it self corrected!

[andytat]

Is it the sender on the right hand side of the fan housing at the back of the engine
and screwed into a block which has the right hand cam feed pipe passing through it?
If it's that one then be careful trying to remove it while fitted to the engine.
I have seen cases where over enthusiastic gorillas have broken the threaded piece
off the crank case. Always remove that block complete with sensor and fix it in a
vice before trying to remove the sensor as they can be extremely tight.
I hope that's helpful Graham.

[911hillclimber]

Yes, that is the one, and the fragile feel of all those parts in the engine stopped me from swopping out the sender.
Odd the unit sorted itself out and worked for 4 more years…

[Nine One One]

The oil pressure gauge receives a signal from the sender, which is essentially a resistor that changes its resistance based on the oil pressure. This change in resistance translates to a reading on the gauge.
2. Testing with a Ground:
Engine Off: With the engine off, the sender should be grounded, resulting in a zero reading on the gauge.
Testing the Sender: Disconnect the wire from the sender and touch it to a ground point (like the engine block). The gauge should move, indicating a functional gauge and wiring.
Testing the Gauge: If the gauge doesn't respond when grounded, it suggests a problem with the gauge itself or the wiring.
3. Troubleshooting:
If the gauge moves when grounded but not when the engine is running: The problem is likely with the sender or the wiring between the sender and the gauge.
If the gauge doesn't move even when grounded: The issue is likely with the gauge itself or a problem with the wiring.
4. Further Checks:
Check the sender's resistance: Use a multimeter to measure the resistance between the sender's terminal and the engine block (ground). The resistance should change with engine pressure.
Check the wiring: Inspect the wiring for any damage or loose connections.

[911hillclimber]

Excellent as always, thank you.
Off to the garage now.

[Nige]

Just a quick test, the terminal on top of the sender can go gimpy. Start the engine, peer through the engine lid so you see the gauge and then wiggle the terminal. Hopefully it's just that.

[911hillclimber]

All fixed now.
The wire from the gauge and the sender is open circuit.
Put a substitute wire across the car and the two worked.
Thus, a new vey long black wire threaded though the car direct and everything works, 60 psi at 800 rpm cold.

Managed to use a nice direct route and you can’t see the new wire.

All back to normal now.

[911hillclimber]

It was the wire from sender to gauge, open circuit.

Rand a lead from both points and the gauge was working as expected, a twitch to Zero with the ign switched, 60 psi / 800 rpm cold running.
Ran a permeant wire from gauge to sender via the easiest route I could find and all is well.
Thus, at last job done!

Off to a hillclimb early breakfast tomorrow, should be nice.

Drive It Sunday tomorrow!

[jb]

Not competing tomorrow at Prescott then.
Maybe see you tomorrow.

[911hillclimber]

No, cancelled last week.
Good reason though, we became grandparents on thursday!

Cannot imagine my wife being at a hillclimb when so much has been going on.
Just back from a visit, mum, dad and 'flash' all doing well.
Baby has no name yet.
Shelsley Walsh next weekend though.