Hello, I'm Jason. I will do my best to answer your question quickly and accurately using the information you have provided.
You do need specific BMW coolant from the dealer
but just refilling it won't help if there is a leak
Once I buy the BMW coolant, should I least re-fill to see where the leak is coming from?
What I would recommend first, since the BMW coolant is expensive, is to add water to the system to determine the leak source.
After you have it repaired, or repair it yourself, only then do you put a 50/50 coolant/water mix in
OK -- so I can just pour water in the coolant compartment, and try to look for the leak underneath -- should I check a specific hose?
Can I even start w/ out coolant? (I assume the engine could overheat?)
All coolant does is raises the boiling point, and lower the freezing point of water, so plain water is fine for initial leak testing...
As far as leaks go, the common areas are the expansion tank (where you fill the coolant) and radiator. Then less common are the radiator hoses
If it's the expansion tank or radiator, would I be able to see this below (vs. above) the engine?
Can I start or drive with water in, in case I need to drive 5 mi. to BMW repair shop?
This depends on where on the tank the crack is (if there is one). If the leak is minor.....just a slight drip.........................drip..........................drip, then the drive should be ok
If it's coming out steadily, don't drive it
but yes, you can drive it with just water if the leak is slow
OK -- that helps -- I will start by putting in water, and then checking the leak (how fast), and where it's coming from. If it's the expansion tank or radiator, can I repair myself (i.e. is there a way to "seal" without replacing this large part?)
No sealants. You will damage your car
but somewhat impossible for me to determine if you can do this yourself, as I have no idea your mechanical ability or store of tools
OK -- I'm not sure either -- depends on the complexity -- let's say I can identify the leak from the radiator, is replacing this with a new one a difficult project (i.e. not having to move major parts, etc...?)
It's about a 2.5 hour job for an experienced mechanic. About a 4-5 on a level from 1-10 in difficulty
OK -- that helps -- I think my last questions unless you have any other "word of wisdom"? (you've been very helpful!)
I'm very glad to help. I do actually enjoy this.
And nope, I think we covered all of the highlights
One last question on this service -- if I have any new questions, I assume that I start a new chat session (with the $29 fee)? I"m OK with this, but just wanted to be sure.
OK -- thanks again. I'll exit now.