Sigh..2 more electrical gremlins!

[911hillclimber]

Starter issue now resolved.
Problem 1:
Ran the engine to prove it worked and saw the oil pressure gauge sitting at max psi, right to the top of the scale.

This has happened before when starting the 1985 3.2 then, by chance, it would drop to normal and stay that way for weeks, then do it again.

Last 3 starts, and the gauge is on max.

Replaced connections on the large cylindrical pressure sender on the engine close to the serial number and the oil temperature small sensor just below the sender, connection dropped off due to corroded wire joint.
Both now re-established.
Ran the engine again and the pressure jumps to max and will not drop despite some tapping on the gauge face.

Turn everything off and the gauge drops to zero.
Before I buy a new pressure sender, is there a way to check it's electric ourput.resistance to see if is the sender or the gauge?

Problem 2:
Clock.
For years it has ceased to work. Used to work and run a bit slow, but a good steady tick-tock.

Now, all I get is a very light tick-tock, even period but no movement of the hands.
Have 12v to the clock, round good.

Guessing the plastic drive gears are broken. Any experiences please to fix it?

Thanks.
Graham.

[jb]

Re clock:
JohnM sorted his a long time ago like this
https://www.ddk-online.com/phpBB2/viewt ... ilit=clock

[Lightweight_911]

Starter issue now resolved.
Problem 1:
Ran the engine to prove it worked and saw the oil pressure gauge sitting at max psi, right to the top of the scale.

Have you checked the earth connection to the back of the gauge ?

.

[911hillclimber]

Thanks JB, will have a read.
Andy;
The earth wire to the side tab on the gauge (original to the car) is continuous to the car's earth, but I have not checked continuity across the clock, 12v in, earth tab.

The clock has the very light ticking (like a clock!) on the bench with a separate battery across it, and is the same in the car, so presume the motor is working, but not driving the hands.
IIRC the clock when working has a loud tick.(irritatingly so).

Gauge:

Just found some things to try on Pelican, but can't copy text to this post.

[fcd911]

Hi Graham

Ditto. Sounds like an earth related issue to me as well.

Good luck in tracing it

John

[911hillclimber]

Thanks John, I thought is was always me with these gremlins.
I hear your doors are back, so maybe a meet up in late July as a practice run for the Silverstone bash?

[911hillclimber]

Spent a few hours on the gauge issue, the clock can wait.

Finally established a few facts.
My Lola race engine has the same sensor and gauge(!) at last an advantage to own it!

The sender resistances are the same @ 10 ohms. I thus conclude the sender on the 911 is good. See later...

The wire from the sender bells through all the connectors (car has a 3.2 in it and modified loom to match the 73T loom).
I belled the loom in sections from the sender to the back of the gauge, all ok.

So this leaves the gauge itself, the original to the car.

Tomorrow I will use the Lola to test the gauge by taking a lead from the loom wire that connects the gauge to the sender across the garage to the back of the pressure gauge in the Lola.
Then take the ground from the Lola gauge to the ground connection that goes on the 911 duff gauge.

When I switch the 911 on, the petrol gauge shivers to the fuel level and the pressure gauge (if ok) should register Zero as the engine is not running. It currently registers about 100 psi with no engine running.
If the Lola's gauge displays zero then all is well as the original gauge is disconnected.

I will then have to find another gauge or get mine repaired. I wonder if Julian Reap can fix them?
At least I know the oil pressure is good on the 911.

What a game, not the result I wanted either!

[911hillclimber]

Could not get the lolasgauge to respond to the 911 wiring.
Decided to back track on the wires.
Wires from sender to back of gauge belled through. Tick.
Put the wires from the snakes nest to the gauge in the car and turned the ign key. Needle jumped to the top of the scale as yesterday.
Started the car hoping the pressure would do something. Nope.

Restarted and the whole lot jumped into life and usual 60 psi cold and tick over!

Waited and revved the engine, gauge moves up with engine rpm. Tick.
Turned engine off.
Waited 5 mins and re started, all working correctly.....

Bloody classic cars!

Will try later and tomorrow and see if it is ok.