OIL guage--where should needle be?

MIK911 · 03-29-2004, 08:56 PM

On my "Oil" guage (shares same cluster as Fuel guage), the needle varies between just above the red zone, to 3/4 way up. Irregardless of throttle position. What's wrong? I know my oil level is OK (checked dipstick).
Is it the guage? Sending unit?
Where SHOULD the needle be on this guage?

thanks
mike
'86 coupe

ischmitz · ischmitz's Garage

It does not matter unless you are idling on flat ground with the engine warmed up.

lateapex911 · 03-29-2004, 10:32 PM

Mine is comical too! Just make sure the "Druck" is good and you're OK.

SRISER · 03-30-2004, 04:29 AM

Theory 1: This gauge was installed by the Porsche factory to prompt new owners to run to their dealer who would then, at $100 per hour, replace the "defective" sender with a new unit. Total bill: $775.

Theory 2: Pay no attention to the gauge behind the curtain. Pressure and temp is only two that you need to be concerned with. Just check the level at full temp, engine running, level ground...I do it every time I fill up.

SC-targa · 03-30-2004, 08:50 AM

I find the oil level gauge on my SC to be useful. When the car's warmed up, idling and on a level surface, if the oil level gauge will show approximately 3/4 full when the dipstick reads halfway between the marks. When the gauge reads near the bottom, I need to add a quart.

Regards,

Jerry Kroeger

MIK911 · 03-30-2004, 11:51 AM

My DRUCK is at 3.5 (out of 5). My dipstick is OK.
Sounds like i should ignore the OIL guage, but do you guys suspect a SENDING UNIT or GUAGE malfxn?

thanks
mike

SRISER · 03-30-2004, 12:08 PM

Mike:

3.5 at idle, fully warm!!?!! As far as a malfunctionof the level gauge...no, just the way they are. Don't spend a lot of time worrying about it. Check levels via dipstick often and worry about temp and pressure.

qcwang · 03-30-2004, 07:25 PM

Hey Mike,

I would agree with the others and check the dipstick often. The Oil level gauge is probably the least useful and reliable out of all the other gauges.

But thinking about this, if there was something wrong, maybe the contacts of the oil level sender unit are slowly wearing out?

When I replaced my sender in the oil tank recently, the new sender made a metal on metal grating sound when I moved the lever back and forth. The malfunctioned one I removed made no grating sound was very easy to move.

See what happens over the next few months.

See ya!

fintstone · fintstone's Garage

The sender is a float attached to a variable resistor via a short arm. The variable resistor causes the gauge needle to rise as resistance increases (or arm rises). There are two leads attached to the sensor. One connects to ground and the other goes to the gauge. If you have a broken wire (or open)...the gauge maxes out. If you have a short (or ground), the gauge bottoms. This link has the info you need:
Oil Gage Reading

Jack Olsen · 08:25 PM

Just for beginners who might be reading this, some things to keep in mind:

1) You can only check your oil level when the car is at operating temperature (180 degrees), and is idling on a level surface.

2) The dash gauge is not particularly reliable, and is only going to function correctly when the car is at operating temperature (180 degrees), and is idling on a level surface.

3) The reliable way to check the oil is with the dipstick, when the car is at operating temperature (180 degrees), and is idling on a level surface. The two dots on the stick do not mean 'full' and 'a quart low'. You want to fill the oil so that it reaches a point in between the two dots. You do not want to fill it to the top dot.

Don't panic if you're a quart low. The 911 oil system has a very high capacity -- this is not like checking the oil on your Ford. In fact, the original specs for the flat six motor were that it would be able to run without damage with only four quarts of oil, up to 4000 rpm. (I wouldn't advise testing this.)

If the engine temperature is higher or lower, your oil level will be different, even though the amount of oil in the system hasn't changed. Try to choose (and warm the car up to) a consistent temperature for when you check it.

Anything I'm missing?

MOMO3.2 · 03-30-2004, 08:32 PM

Check your oil EVERY time you fill up.

My oil level guage works great on my 87 Carrera. when my car is at operating temps and it is on level ground at idle, the guage basically matches the oil level on the dipstick perfectly. It is a great way to verify where you think the oil level should be. I like it.

Mike

MIK911 · 03-30-2004, 10:00 PM

When i check my dipstick w/ engine at idle, a few seconds after removing the oil filler CAP, the engine stalls/dies. I only have a few precious seconds to pull the dipstick while the engine is still running. Is this common?

Quincy--you're supposed to be working!!!!!!!

thanks
mike
'86 coupe

fintstone · fintstone's Garage

Mike
Try this link for ideas:
Stall at removal of oil filler cap