Take the 2-minute tour ×
Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. It's 100% free, no registration required.

My e46 M3 would not start when I got to the parking garage after work. When I first turned the key, I heard a sound like grinding gears, but I was so startled that I immediately stopped trying to crank the engine. The interior lights and radio flashed for a fraction of a second when this happened, and the clock on the dash reset itself. A couple of seconds later I tried cranking again, but all I got was the sound of the starter relay clicking away. The engine did not turn over, nor did I hear any grinding noises. Is it the starter, or something else? How would I check this?

I should also mention that I was able to push-start the car and get it running, since it has a manual transmission. Thanks!

share|improve this question
add comment

4 Answers

up vote 9 down vote accepted

Your battery was dead.

In many cars, when the battery can't provide enough cranking amps, you will hear a clicking instead of the normal starting sound.

The starter battery draws a lot of current. When that happens, the voltage available to the rest of the system drops dramatically, especially if the battery is weak. That's why your clock reset itself.

Hook up a smart charger. A cheap one is a Battery Tender Jr. Avoid a dumb charger, which will gladly push 13.8V at 2A in to your battery until all the electrolyte has boiled away. A good charger will have bulk, absorption, and float stages. A really good one will have a desulfate stage, which can help revive an older battery.

You need to figure out whether the problem is in your charging system or in the battery. A mechanic or a battery shop will have a testing tool that will measure the CCA of your battery. To get the best possible test, charge the battery to full, then let it rest disconnected for 24 hours. If the number is very low, your battery can't do the job. Letting a desulfating charger work for a long time may make a difference, but if this is your daily driver and you don't have a spare battery, you probably should just replace it.

If you decide to replace your battery, check out How do I apply dielectric grease to my battery?

If the battery checks out, then the problem is in your charging system. Perhaps there's a loose connection, or perhaps your alternator is bad. See your service manual for instructions on troubleshooting the charging system. You'll definitely want a good multimeter at this point, with 3 1/2 digits of precision.

Remember that batteries have lead, produce hydrogen, and can get acid on things. Nitrile gloves, goggles or face mask, clothes you want holes in, and wash up well afterward.

share|improve this answer
    
I just checked the voltage on the battery and it reads 9.5 volts...Good call. Dead alternator. –  JeremyP Mar 12 '11 at 13:31
    
Great call, Jay! Some "battery" problems I've had have turned out to be the alternator needed to be replaced (if the battery wasn't at the end of its life). –  Peter K. Mar 12 '11 at 15:12
    
Update number 2: I don't think it's the alternator. I tried charging the battery (with the battery leads attached), and I could not get it to hold more than 11.5 volts. Then, I disconnected the leads and continued charging, which brought the voltage up to 13.05. I'll see how long that holds. Also, I was unable to jump start the car, which means it's almost certain the starter motor fragged itself. My guess is that there is some sort of electrical short in the starter, which is causing the electrical gremlins. That would explain all the symptoms (gear grinding, battery discharge, no start). –  JeremyP Mar 12 '11 at 20:20
1  
@JeremyP: Please charge the battery to full with a smart charger, let it rest for 24 hours, and then have it tested. It's hard to draw conclusions about anything else if your battery is bad. –  Jay Bazuzi Mar 12 '11 at 21:47
1  
I totally forgot to post a response to this issue. I bought a new battery and the car started right up. Thanks for help! –  JeremyP Aug 8 '11 at 2:35
show 5 more comments

I'm not sure about the Beemers, but many starter motors have an (dis)engagable gear /clutch that will connect the starter motor to the fly wheel. Once the engine starts, the gear disengages.

From your description, it sounds like that gear was munged somehow. Also, you may have dislodged it by push-starting the car.

share|improve this answer
    
I got home and tried to restart the car in the garage, but I get the same clicking. I don't hear the starter turning over at all. –  JeremyP Mar 12 '11 at 13:26
add comment

If you've tested the battery and determined that the battery is good, and if a jump start doesn't solve the problem, you could remove the starter motor and take it to an auto-parts store or a mechanic. They can test the starter motor independent of the other systems in the car.

While the motor is out, you can also inspect it for damage.

On most cars where I've removed the starter motor, there are typically 2 bolts holding it to the transmission housing and two wires connected to the solenoid.

share|improve this answer
add comment

If you believe it's not the battery, it could be your starter motor solenoid. I've had a solenoid go on a couple of cars I've owned, it seems to be quite a common thing. The solenoid is what you hear clicking when it can't get enough current to turn the motor over, but it could also be on it's way out and getting stuck perhaps.

Usually when a starter motor goes it's either brushes or your solenoid. Go get it tested, a lot of places will do that for you for free if you ask nicely.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.