machine gun sound. starter?
 

Long time, no see. Main reason for that is the old girl's been sitting in the garage for the past 8 months.

I jumped in one morning, turned the key, and heard "clackclackclackclackclackclackclackclackclackclackclackclackclackclack!"

Kind of like a machine gun. She wouldn't turn over, just clackclackclacked.

I had another car and no money to fix the problem back then, so she's been sitting for a while. I'm sure the battery is now dead. So...

I want to get her back on the road for the summertime. I'm a sucker for driving around in the sweltering heat with a hot engine and no air conditioning. ;)

I'm going to put a new battery in and fix whatever the machine gun problem is. Anyone want to diagnose? Sounds pretty common, but I'm not too sure if it's the starter or the alternator. Any help would be greatly appreciated. Thanks!

The machine gun was the starter solenoid attempting and failing to start the car. It's POSSIBLE that this can be caused by defective starter or solenoid, but 9 times out of 10, it's the direct symptom of the battery being too weak to start the car. This can, of course, be a one-time result of a drain, or can be the cumulative effect of driving for a while without a functioning alternator.

Before you put in a perfectly good new battery and risk deep-cycling it, jump-start the car from another car and report the results. You may have to let the donor car idle, or even have someone hold it at 1500 rpm or so, for 15 or 20 minutes to provide charging time before trying to turn the heavier diesel over. If, after your best jump start effort, it makes the same sound, it's time to look at starter problems. If it starts right up, then you're looking for charging system problems.

Before starting after sitting for 8 months you want to pre-oil the engine to avoid damaging the engine. There are a couple posts touching on this.

The noise is the starter solenoid trying to bump the gear into the flywheel. Did you try jumping the car's battery? That noise is usually due to a low battery.

EDIT:
If the clacking continues with a good source of power, you can try banding on the starter with a hammer/rock/crowbar. Mine got stuck once in cold weather.

Dead battery. Almost any engine will make a machine gun noise when the starter doesn't have enough juice to spin.

Here's some physics behind it.

The starter solenoid clicks on and the starter puts a HUGE resistance across the battery. Say, 750 Amps on a diesel (give or take). That amount of amperage is enough to reduce the required voltage and amperage to the solenoid and it clicks off. When the solenoid clicks off, the battery quickly "recovers" from the current draw and the solenoid clicks back on, this repeats so fast it sounds like a machine gun.

Nothing to worry about, as said oil the cylinders throw a battery at it and tinker away!

Hope that helps :)

forgot to mention...
 

When this happened, the battery was only 4 months old. With that in mind, does a bum alternator seem likely?

made the same sound after charging
 

Finally got a nice day and some friends to help me push her out of the garage. Turning the key made no sound. The battery was totally dead. After about 10 to 15 minutes of jumping with the gas pedal pushed down to around 1500 rpm, turning the key gave me the machine gun noise again. Also, the windows and radio worked. I kept charging it for a while longer, but it didn't get any better. I took the jumper cables off and tried turning the key again about 20 minutes later. Not a sound. Totally dead again. As I mentioned before, the battery was only 4 months old when this happened. I just don't have the dough to buy the wrong part. Is this sounding like an alternator or a starter? If it's the alternator, am I going to have to drop $125 on another new battery, too, or will the new alternator help it get jumped?

Thanks!

An alternator won't do you any good until it's running, what I'd do is get a battery, not a cheapo, make sure it has the required amps . . . once it's started you can take your alternator to most parts stores, and they can check it for ou if you don't know how to check it or don't have the tools . . . your battery won't go dead just driving it to the parts store . . . also check to make sure you don't have something left on that could drain the battery.

Edit to add:

If your "new" battery went dead in 4 months, take it back to where you got it from . . . they should give you another one or your $ back!

Battery is low, needs charging.

How big was your friend's battery? What sort of car were they using to help jump? And how thick/heavy were the jumper cable wires? These diesels are heavy and hard to turn over, huge current draw from the starters, and it's entirely possible you were jumping with equipment that wasn't large enough to help.

you need to check your connections. if you tried to jump it for 15 minutes and it didnt get better, then your battery might have juice it just cant deliver..

The car being used to charge was a V6 Dodge Dakota. Not sure what the battery size was. Definitely not physically as big as the Benz battery. The cables were the type that come in any emergency side of the road kit. Not industrial strength.

Since it's a Mercedes and I have road side assistance for life, should I call a dealership and have them send someone out with a charger? Think that would get it going?

Those two facts (tiny truck, tiny engine = tiny battery) and barely-sufficient jumper cables - are more than enough to have prevented it from starting if it was stone-dead. When I left my lights on and the only helper vehicle I could locate was a Jeep Cherokee, I had to charge through my heavy jumper cables for over twenty minutes with the Jeep at an increased RPM before the thing would turn over fast enough to start, and even then it was a reach.

Calling roadside assistance and asking them for a start might get you going, but I don't know if they consider your own driveway "roadside" enough to be worth the trip. Battery chargers aren't terribly expensive and they're one of those appliances you use the rest of your life after you buy it. I'd invest in one, so I could repair my own damage in situations like this.

Meanwhile, checking the battery connections is the best advice i've read so far. Take off both clamps, clean both the clamp surfaces and the posts themselves with a wire brush, if there's any visible acid clean it up with a paintbrush (that you don't want to paint with) and some baking soda and water mixed together. Clamp them back down good and tight and then try again, with a jump if possible. Once it starts, haul it to a parts store and have them check your charging system.

Mcparts will charge your battery for you- especially the one that sold you the battery. they may even replace it IF it's defective. but that said, I have no less than 4 battery chargers. get one with engine start feature, it's worth the $$.

I cleaned the terminals when I changed the battery. They still have a coat of lithium grease on them. That said, I'll pull the cables off and make sure they're on there tight. I'll see if I can get my neighbor with the big old diesel Dodge to give me a jump when the weather clears up. If that doesn't do it, Ill bring the battery back to Strauss, if they're still open -- they're dropping like flies around here.

Thanks for all the help. I'll post an update at some point. Looks like rain for the next couple days...:(