QuestionQUESTION: i have a 1997 bmw z3 with 70000 miles on it that ran perfect for me over 6 years.recently it would not start making only clicking noises.jumped it and it started right up,next day dead again.towed to my mechanic got the alternator and battery replaced.ran for three days fine,on the fourth day same clicking noise car wont start.towed again to the mechanic, they say they cant find a problem after running all the electrical tests.go to pick up my car after hours after mechanic told me it was running again.same clicking noise again car wont start again.the guys working on the car don't know what is wrong,and they have had my car for two weeks now.my bill is already over a thousand with nothing fixed.sorry for the length of this question but i am desperate for a solution.anything you can suggest would be greatly appreciated.
thank you
ANSWER: I know you're probably thinking the same, but this is one of those few times when it would have been worth taking it to a BMW dealer.
Sounds like you're not getting enough juice to get the starter going. You mention jumping it once, and it started that time. I'm going to assume that's always the case.
Could be a couple of things, but I would first look at if the battery is draining. A drain in your electrical system would bring the battery too low to start, even a new battery after as few as a couple of hours if the drain is significant.
Disconnect your battery, and using a charger, charge it up. Reconnect it and see if it starts. If so, leave the battery unconnected for a day, and then reconnect and try it again. If it again starts, then leave it connected, and try it again the next day. If it doesn't start, you have a drain.
If you have a digital volt meter, you can put it in line to look for current draw. When the car is turned off, the voltage should be some value, perhaps around 0.2 amps. After about 16 minutes, it goes into a sleep mode, where it drops to about .06 amps. (These were the values for a 740 I fixed this on.) Anyhow, if the current doesn't drop to way below .1 amp, you have a drain in your system.
What would that drain be? It's a long and tedious check of the electronics to find it. If you know your way around the electronics in here, start by disconnecting 1/2 of the car's circuitry to find which half it is. Then take the "bad half" and cut that in half. And again. And again. And again. Until you finally find the component that is bad.
If you don't know your way around electronics enough to chase this, it can be very, very expensive.... mechanic's hourly rate until he finally finds it. Then you find out what it costs.
I bought a 740 cheap because of a similar problem, and it took about 20 manhours to chase the cause down. At hourly rates, that can be painful. (If you live near MN and want to get rid of it, let me know.)
So if you can debug electronics, you likely have a long but not too expensive job ahead of you. If you don't, you really don't know what it will cost.
Good luck, and write again once you find out a little more.
Adder:
Check this link:
http://www.wikihow.com/Find-a-Parasitic-Battery-Drain
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QUESTION: hi john
thanks for the quick response
looks like i have no choice but to let the same mechanics find the problem after the money i already paid them.i now wonder if i needed the new alternator and battery or if i am just paying for things they are guessing at.
i love the car and before this i had no problems but i still could not sell it at this point.
i do remember the guy saying he could not find a drain significant enough that should be causing this problem after he had it hooked up to his meter.
i let you know the end result
thanks again
AnswerI would be concerned that if they have gone this far without finding it, they are likely to spend a lot more time on trial and error.
I would recommend taking it to a BMW dealer. (I don't say that often.)
As bad as it would hurt to walk on your current mechanic now, it will hurt a lot more after another $1000.
