When To Stop? - PeachParts Mercedes-Benz Forum

weiner0stick · #1 01-31-2017, 07:58 PM

First Poster Here......finally ending the lurking.

Friend had a 1973 240d and having no car and some extra money, I bought it and attempted to help a different friend move to the west coast.

Coming from Wisconsin the super clean diesel popped a glow plug in the middle or Iowa and another in Nebraska. Abandoned it with the nicest local mechanics ever, who stored it for a week and a half, and got it running after I came back, and drove it straight home.

https://www.flickr.com/photos/63206504@N02/5752662117/

Sold that to a gentlemen in Philly, PA.

Well, then I wanted a small diesel truck, so I eventually got a rotten Isuzu Pup motor installed into a 1997 Isuzu Hombre, aka Chevy S10 or GMC Sonoma).

Completed that in 3 months as a beginner and the diesel fever really set in.

Making a Pup'bre (97 Hombre meets 81 Pup) - IsuzuPup.com

A mechanic turned friend eventually helped me get a running 1984 300TD and a 1984 part 300TD.

I installed new pads and rotors all around, with new hoses and calipers in da back. Replaced front wheel bearings. A Molly purge and new filters all around had it running strong as ever. When it isn't colder then 40, it fires up first try, with authority.

The radiator cracked a little at the very top this spring, but I installed one of those little bandages for plastic radiators and that held until this early winter, when that popped off.

So then, a week ago the wether was clear enough to pull and install the parts wagons radiator, which was pulled off cleanly, with a little fuss with the threaded transmission hoses.

On the first drive then after that, after topping off fluids and being driven for 15 minuets or so, up to temp, the head lights stuttered off, then after a railroad track they turned back on, then pulling into a parking lot, hitting the small incline, they shut off again.

EDIT: after 330,000 miles, we leave the key in the tumbler all the time

I got to the wagon and opening the drivers door the buzzer was buzzing.

I assumed something basic, so I unscrewed the ground from the car, sanded it shiny, and reinstalled it.

Opening the door, no buzzing.

Turning the key, no power to dash, no starting chug, no nothing. D.O.A.

Pulled the battery, was a little low, but still had 12V. Charged it full and reinstalled. Cleaned up the hot terminals split component. (sorry I don't know the name) On top the the passenger wheel well in the engine compartment

Still nothing.

I looking the diagrams, I am guessing the wires are rotted going from the battery hot to its first led, which I think is the starter or alternator. It visibly look corrupted from the top view.

??What can simply stop all power from getting to the inside the vehicle??

Turning key does nothing.

Some thing easy, replace the wiring from positive battery terminal to starter?

Can a bad light switch stop the current flow?

Strange and strange it is.

THANKS
Chris
1984 300TD Crust Wagon

PS
, but I was all excited to finally get to the SLS system...

97 SL320 · #2 02-01-2017, 06:28 PM

You need a power distribution wiring diagram and look for the first branch after the positive battery terminal. ( the split component you are speaking of? )

Look at these wire terminals where they bolt on and where they are crimped to the wire. Sometimes acid will wick up the wire causing ti to lose contact.

ROLLGUY · #3 02-01-2017, 08:11 PM

Check the ground strap from the transmission bolt to the chassis.

Dan Stokes · #4 02-02-2017, 08:40 AM

I've said it before on here and will probably say it again - most odd electrical issues are caused by bad grounds. Remember, the battery needs a circuit - battery + (called "B+ in most diagrams) to the starter which has to be grounded to the engine block, then the block and body need to be well grounded together, then the block and body grounded back to the battery negative. So it's a big loop. The starter can have a poor ground to the block, there needs to be a GOOD ground from the engine to the body, and finally a great connection back to the battery. Just because the strap is there doesn't mean that the ends are clean and making contact so clean ALL those types of connections.

There will also be lots of connections from relays, lights, etc, that ground to (usually) the body. After a ton of miles those may need cleaned, too. I sand the metal then use anti-seize and a star lock washer to assure a connection. The anti-seize (which is a metal-based grease) keeps the bare metal from rusting and keeps the water out of that connection while the star washer cuts into the metal and makes a mechanical connection.

Try these and get back if you need more help - and good luck!

Dan

barry12345 · #5 02-02-2017, 09:27 AM

To test the heavier grounds. Take a jumper cable from the negative terminal of the battery to the body shell or some component that looks like your clamp can make a decent connection on it. See if the electrical circuit is energized. Then try the connection to the engine.

Nothing electrical at all I would suspect if a ground is bad from the negative terminal to the body shell before testing. If it is a ground.

You can also take a cheap voltmeter and find it. It could be an open positive cable or connection as well.

funola · #6 02-02-2017, 11:09 AM

Quote:

Originally Posted by weiner0stick

......................
I looking the diagrams, I am guessing the wires are rotted going from the battery hot to its first led, which I think is the starter or alternator. It visibly look corrupted from the top view.

??What can simply stop all power from getting to the inside the vehicle??

Turning key does nothing.
..............

Yes, the lead from battery + post goes to the starter first, then branches off to the terminal block on passenger fender, then to the light switch- all un-fused.

The battery - post goes to passenger fender via a short 12" cable, then thru the chassis all the way over driver's side floor pan via a copper ground strap to transmission bell housing. Mercedes could have done this better with a much shorter ground path with a ground strap from passenger fender where the - cable is direct to the block or better yet, to starter motor ground. But you have to work with what you have.

Check that these connections are clean and tight.

Dan Stokes · #7 02-02-2017, 11:53 AM

I gave general automotive electrical system info and Funola has given the Mercedes-specific version (I don't own a Mercedes bodied vehicle so I'm not much help there). This is all really good info and ought to get you headed in the right direction.

Dan

jay_bob · #8 02-02-2017, 12:56 PM

A bad cell in the battery can cause this too. It will put out 12 V at no load but when the current goes up, the voltage drop caused by the high internal resistance of the bad cell drives the battery voltage in the dirt.

Remember that to make 12 V it is six 2-volt cells in series. If one of the cells is bad, it is like sticking a high value resistor in series with the battery. Your meter will still register 12 V, because it draws no load. However, when you hit the starter, the current draw through the high resistance creates a large voltage drop (effectively the voltage of the remaining cells).

Either this issue, or a bad connection, causes the infamous problem where your low amp loads (dome light, key buzzer, radio, etc) work, but as soon as you hit the starter, and try to draw several hundred amps, the car goes flat dead.