Oil Pressure Warning Light 911SC

[peetie]

Oil pressure gauge and oil temp. gauge both indicate normal but oil pressure warning light is on. Should I drive it ? Where is the oil pressure switch for this light located ? No shops within 100 miles will work on the old air cooled engines so had a local mechanic rebuild upper engine due to broken head bolts but now the warning light stays on. This mechanic is not Porsche trained and I am trying to find the answer on this forum. Any help would be appreciated.

[dannobee]

The oil pressure sending unit is just above the right side timing chain, on the oil line going to the right cam housing.

The oil pressure switch (for the warning light) is at the back of the engine, on top, near the breather and the thermostat. Sounds like it's bad, or the wire isn't hooked up correctly.

[Walt Fricke]

The idiot light switch closes a circuit from the warning light to ground with the engine off. As soon as about 0.4 Bar pressure is in the oiling system, the switch opens, and the light goes off.

When I first had my 2.7, on vigorous cornering the light would flicker. That was due to the connector having been crimped on with some bare wire showing, which could flop around and hit a metal piece, grounding it.

a) Engine off, key to run position: does the idiot light light? If it doesn't, chances are the wire isn't connected to the switch.

b) The switch isn't expensive, and after some years they are prone to leak. That makes a mess over time (not a huge leak), and it shouldn't make the switch fail, but maybe? The chances that the wire to the switch is grounding somewhere else are small, but I suppose possible.

c) The switch is a bear to get at with the engine in the car. Best to use the search function for "partial drop" if you want to get at it, check the wiring, and maybe replace it.

[AUSTmike]

I have 3 lights going from top to bottom of the oil pressure gauge!there is 2 red lights top and bottom and a green light in middle.
The green and bottom lights work on turning key to start engine then they turn off once engine has started and running.
can anybody tell me what the top light is..it doesn't work because its not connected to anything.
This is how it came when i got the car.
https://i.postimg.cc/Wp7fWw2X/Pressure-gauge-lights-on.jpg

[JSV798]

I think that might be the overheat light for sportomatic transmission. In other words your car had a sportomatic gearbox when new. In which case the last 4 digits of your engine number begin with a 9.

Roy

[targa80]

Originally Posted by AUSTmike

I have 3 lights going from top to bottom of the oil pressure gauge!there is 2 red lights top and bottom and a green light in middle!
The green and bottom lights work on turning key to start engine then they turn off once engine has started and running!
can anybody tell me what the top light is!..it doesn't work because its not connected to anything!
This is how it came when i got the car!
https://i.postimg.cc/Wp7fWw2X/Pressure-gauge-lights-on.jpg

If you have an SC model then the light is empty and is not used. I did research it’s purpose but it was so long ago I can’t remember what it was previously used for. I ended up using it for a keyless entry alarm indicator light.

[AUSTmike]

Thanks guys..my car is a 1977 2.7ltre with the 915 gearbox it also has the 5 blade fan with the mag case.

The last 4 numbers on the engine 107.7R

[JSV798]

My driver's manual (1978SC) says:

"For vehicles with Sportomatic, an oil temperature warning light is built in at the upper part of the gauge."

My car was originally a Sportomatic and has this feature. It was fitted with a 5-speed 'box before I bought the car. Its engine number is 6389217, with the 9 indicating an engine for a Sportomatic car. Also of note is that the distributor does not have a vacuum advance and I wonder if this is because it was a Sportomatic.

Roy

[spuggy]

Originally Posted by JSV798

My driver's manual (1978SC) says:

"For vehicles with Sportomatic, an oil temperature warning light is built in at the upper part of the gauge."

My car was originally a Sportomatic and has this feature.

"they're all like that Sir".

My '77 also has the unused Sporto warning light hole, never had a Sportomatic.

They used the same clock body (with the 3rd unused warning light hole) up through the SCs. Presumably until they dropped Sportomatic as an option (surprisingly late, IIRC).

Originally Posted by JSV798

the distributor does not have a vacuum advance and I wonder if this is because it was a Sportomatic

Curious... Never heard that before about Sportomatic--equipped cars. Made me dig out the factory manual....

My (1981 print date, they vary) Vol III supplement, cites timing specs with "vacuum connected" for 1978 SC, and "vacuum disconnected" for 1980 & 1981 SC - no mention of anything being different for Sportomatic. Could have been in a supplement I guess.

So, what - you just don't have a vacuum pot? What distributor type is that?

[timmy2]

My 78 Euro German delivery, has no vacuum pod. As original.
The “U” for vacuum is missing in the part type number.
Some didn’t have it for emissions.

[AUSTmike]

I found this video on YT from Klassik Automotive Training school about the oil pressure and safety valves.
In this video there are some engines that have the older oil control piston with the hole in them.
my car is from 1977 and i may have the older oil piston which could cause my engine to have low oil pressure once the engine is up to temp.
I will do a check first to see if i have the older piston by draining the oil and undoing the oil pressure control nut and remove the spring and piston to see if this is the case.
the newer type piston is fairly cheap and i can order one easily.

Just a quick question has anyone had success in replacing their oil control piston and improved their oil pressure on the druck gauge?

courtesy of Klassik Automotive Training School

https://www.youtube.com/watch?v=z-owtgB4E3c&ab_channel=KlassikAutomotiveTrainingSchool