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Discussion Starter #1
I have a 2001 Z3 2.5i automatic. Yesterday I started it and the red oil pressure light came on before I exited the garage so I turned it off, checked the oil level and found it to be down - probably at least a liter. This is unusual because for the three years I've owned it it hasn't used any oil. This morning I checked the oil and it was right at the full level. Hmm! Turned it on for 30 seconds until the oil pressure light came on, turned it off, checked the oil and it was low again. Ideas please - thanks.
 

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BMW CCA 1405
1997 BMW Z3 1.9
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5,175 Posts
The sump holds 7 liters so a liter low is not going to affect the oil pressure.
Of those 7 liters, a liter might be distributed around the engine within 30 seconds of starting, and not reappear on the dipstick until several minutes after the engine is turned off.

If the car has high miles, and the oil pump is worn, and the oil viscosity is low, the red oil pressure light might come on at hot idle. But none of these factors appear in your case. So I don't know why the light comes on.
 

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Discussion Starter #3
Thanks for your thoughts. Mileage is 88k - not particularly high. Anyway, I'm off to my sons wedding in Montreal tomorrow so I'm not going to be able to do anything for a week. There's no puddle of oil or exhaust smoke so I'm thinking of a number of issues, the oil sensor light has shorted out (I wish), there's a blockage somewhere or the gear has fallen off the oil pump. Need to find out if the engine is moving oil. Thanks - I'll keep you all posted on progress when I return.
 

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If the engine has no oil pressure, it will make quite a racket when you start it. Lots of lifter, bearing, rod, and piston slap that will not stop in a second or two. If it makes a racket for more than a few seconds, SHUT IT OFF and do not restart. You're wearing out the engine. Tow it somewhere that you can have it checked.

You might also remove the oil filler cap and, very carefully, with the engine running, shine a light into the hole and see whether there is oil being circulated. This test is not for the novice or amateur mechanic.

Leaks can be difficult to find. Place a piece of clean cardboard underneath the car and (assuming it is NOT making noises like I mention above) take it out for a spin, park it over the cardboard and have a look in the morning. If you're losing that much oil, I imagine you'll find the signs of a leak somewhere, maybe everywhere (there are several likely suspects...)

You're in dangerous territory here. The oil light illuminates for a reason. Pay attention or pay the price.
 

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Discussion Starter #5
Finally got to fixing this problem. Changed the oil pressure sensor - bit of a pig to get to, need to remove the air box and move the steering fluid reservoir to the side. Then I was able to get a crescent wrench on the sensor which after a 1/8 turn came out easily by hand. Started the car and the oil light went out after 5 seconds - boy I was happy - only $9 too!
 
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