will2k

545i with 130k miles, car turns over but won't start, I looked under the car and there was a puddle of oil, right side near the alternator. I heard it won't start because of oil pressure to low? Is this correct? I believe a gasket broken somewhere.

BimmerFan52

The engine will not be prevented from starting if it is low on oil, but if the oil is critically low you could do damage to the engine.

Do not crank the engine again until you have checked the oil level on the dipstick.

If the oil is on the floor under the alternator the leak is probably the profile gasket underneath the alternator bracket, which in the later stages of leaking can loose a significant amount of oil.

The two questions to answer right now:
1. Is gas getting to the engine?
2. Is a spark firing at each cylinder

will2k

The oil is at normal levels.

Is there a DIY to take a look at the profile gasket underneath the alternator?

I cannot find a diagram on where the fuel filter is is I can pull it off and see of fuels coming out, do you know where that is?

How do I check if it's sparking the plugs?

BimmerFan52

There are several DIYs for replacing the alternator bracket gasket, but be ready for a big job. Unfortunately the alternator bracket is only removable after the engine mounts have been loosened and the engine raised slightly.

The fuel filter is located in the gas tank. To access it the back seat is taken out and a cover is removed to expose a port the top of the gas tank (which must be drained prior to starting) to get to the fuel filter. There are easier ways to check if gas is flowing.

But first check to see if when you turn the key you can hear the fuel pump start (usually audible if you sit in the back seat).

For the spark plug you can hold onto one of the coils while the key is turned but it is a hair raising painful experience. Using a tester is much easier. This is one of many different types on the market.
Performance Tool High Energy Ignition Tester, Model# W84600 | Automotive Diagnostics| Northern Tool + Equipment

DavidF

Just to be clear, alternator is on the left side. If this is the side the leak is on, then probably the profile gaskets under the engine mount bracket. If oil leak on right side (maybe you confused a/c compressor for alternator) then leak is probably from vacuum pump or oil pressure switch. Both of these are MUCH easier to repair than profile gasket.

BimmerFan52

DavidF is correct.

You need to always think of yourself sitting in the drivers sit facing forward when referencing right or left.