911L Oil Temperature-Pressure warning light

[gdupl0ck]

When I drove my 1968 911L Sportomatic last night I discovered i had a warning light I was unaware of!

I have an orange (rectangular area) warning light at the top of the oil temperature gauge graduations (see image) which flickers then comes on full when engine is under load.

Oil temperature needle is at low end of white scale. Oil capacity indicated is 7 to 8 litres. Oil pressure is indicated at 50 to 60 psi (is this reasonable?).

I can't find any sign of the feed to this light on circuit diagrams i have. Is it Temperature or Pressure related?

Can anyone give me any advice on this please. I am naturally not keen to continue driving until I find out more about this.

Also, if anyone can tell me what might be causing the light to come on I would be grateful. Oil was changed for Valvoline VR1 20W/50 some 500 miles ago (I believe this was used previously with no trouble).

Surely this can't be just hot weather!

[sam]

Can't remember what pressure these used to run, but for sure if the ambient is high and you are travelling at low speed/revs your oil will become hotter and 'thinner' = lower oil pressure, there will be an oil pressure switch (driving the warning lamp) if that's what it is, and a separate sender for the pressure gauge

[Sean Smallman]

I wouldn't have thought the temperature last evening could be influencing the engine temperature.

A faulty sensor seems most likely.

[lindsayhbrown]

Does the light go out if you rev the engine

[gdupl0ck]

Hi Lindsay,

The light illumination does become somewhat intermittent if you rev the engine. It does not go out completely.

I have since disconnected both the Oil temperature and Oil pressure sensors wires at the sensor end and it still comes on.

Looking more closely at my circuit I think I can see a connection through to the Oil Capacity indicator in the other dial. So I think this Orange warning is for low Oil capacity. I have yet to disconnect the Oil level sensor wire as it is more difficult to get to.
There is definitely sufficient oil in the engine/tank.

Thanks

[gdupl0ck]

Thanks to those who have looked and responded.

My mystery is now solved.

If I had researched fully in the first place I could have sorted this quicker.

I had all the information in my Sportomatic Users Handbook and Official Porsche Manual.

The Sportomatic has two electrical connections to the Torque Converted: an oil temperature switch and sensor for the indicator light I had coming on and the temperature guage. There is no temperature sensor on the Timing chain cover.

I found the lead to the temperature switch had come loose at the converter end when I jacked up and crawled underneath. Easy problem to fix you think! This connection is just about visible on the upper surface between the torque converter and the engine. Unfortunately it's not in the engine compartment, it's just in front of the baffle. You can't get your hand to it from the other side either!

Peeling back the rubber "sealing" strip at the base of the baffle where it meet the engine you can just see things. Drastic action needed so I carefully cut the sealing strip and pulled it out of its metal groove to get just enough access. Then holding it with some used "once only use" artery forceps from previous employment I managed to refit the cable onto the connector. Phew! The sealing strip has now been carefully fed back into it groove and it is hardly noticeable that it has been cut. The warning light no longer comes on either!!

This does not quite sort all my problems as when I bought the car the temperature gauge never moved when the car was driven. I then installed a temperature sensor into the blanked screw hole above the drivers side timing chain housing and connected this to the guage which had no wire connected. This has given me an oil temperature reading for the past three years, never moving higher than shown in the above image.

I still have to trace the green wire from the temperature sensor on the torque converter and see what has happened to this. Then I can hopefully have the torque converter oil temperature displayed. If my be this sensor does not work which could be why it was disconnected when I bought the car. Anyway, rain started so this will have to wait, just got car inside in time.

Sportomatics are fun!! I'm going to beat it! It's good to sort things yourself even if frustrating at times.

Graham

[Sean Smallman]

Glad it's sorted, see you on Saturday

[lindsayhbrown]

Result, glad it was a relatively easy fix, albeit fiddley

[gdupl0ck]

Thanks Lindsay. Oil temp sensor on torque converter seems not to be working so reconnected to my sensor on timing chain supply.