Can't start my car

My car won’t start, and I hope I can get some clues as to what might be the problem before I call a tow truck/trek out to a gas station/set it on fire:

The starter turns, and it’ll go wah-wah-wah-GRNNG-wah-wah-GRNNG-wah-wah-GRNNG-wah-wah, etc. This started when I was trying to get to Thanksgiving dinner, and I haven’t been able to drive since. It doesn’t seem to be a battery issue, because I have one of those portable jumping batteries and that didn’t help. I wonder if it had something to do with the sub-zero temperature that day (I just moved to Ohio from California last year, and don’t know anything about keeping my car running in cold weather), but I tried starting it again this week when it was 10 degrees Celsius out and still no dice. I was also kind of low on fuel the last time the car moved.

What might be going on and what should I do? I’m a broke student in the middle of exams and it’s freezing out, so I can’t really experiment to figure it out. It’s a 1994 BMW 5-series.

Probably the first thing to do is make sure your coolant has freezing protection to the lowest temp encountered in your climate. While it was in Calif it might have been diluted during some repair or another, and still be ok, but not ok in Ohio. Suggest to get on that tout de suite, as severe engine damage could result. Second would be to put in 5 gallons of gas, so as to eliminate lack of gas as a possibility (I was a broke college student one time too!). If neither solves the problem, you likely have a fuel or spark problem. You need a mechanic to run some basic tests on the ignition and fuel systems to decide which it is.

Get a can of starting fluid, follow directions, if it kicks, go for heet, seafome or techron etc.,

I think if its going GRNNNG while cranking, your starter motor needs to be replaced. The solenoid is kicking out and not pushing the starter motor gear into the flywheel on the engine. A starter motor should crank the engine continuously until the battery wears down. Now if it cranks ok and just doesn’t start, that’s another issue. As posted you can determine if its spark or fuel by the starting fluid, a spark tester, or a spare spark plug on one of the spark plug wires. The cost of a car though is only part of the total cost so you have to expect some repairs once in a while.

@GeorgeSanJose: I definitely haven’t paid attention to the coolant, and it gets down to around -15 degrees Celsius here. Do you think it’s possible I’ve already damaged my engine (it’s parked outdoors)? I’ve tried to start it when it’s around 0 degrees, but not when it’s -15. Last winter I did do some driving at 0 degrees.

@Bing: The GRNNG sound is my approximation of the sound of it firing up. It’s like it’s trying to fire up, but it doesn’t take. If it’s a spark problem, would it suddenly conk out like this with no warning? I’ve never had it not start on me, except when I’ve left it sitting too long and the battery died.

Thanks a bunch for your collective wisdom. Will look into starting fluid too.

Oh, then you’re back to fuel or spark. You might just need a tune up or you might be having a choke problem on the carb if it has one.

@Bing: No carb on a '94 Bimmer (or in any '94 car sold in this country).

Any local mechanic can quickly test and tell you OP if your coolant is offering enough protection for the climate you live in. Rather than speculate, suggest to have that done. Inexpensive DIY gadgets for this function are available at retail auto parts stores too. You could save some $$ by testing the coolant protection yourself if you like.