Help a newbie '77 123 Starter motor

I am not familiar with your particular model but I am familiar with cars in general (Jaguar).

When an old car is parked for a long time, it's not unusual for the starter brushes to fail from making a good contact. If you can move the position of the brushes by a minute amount you may solve your problem

Tapping the Body and the solenoid as you have done sometimes works. Try again with a piece of wood. A piece of wood was part of the tool box on my wife's Mustang . It was used more then a dozen times.

If the car is manual, there are ways of forcing the starter to rotate a little, but they are too dangerous for people without experience.

If you can try the following: Connect a voltmeter between the heavy wire that goes to the starter, from the starting relay and the starter body (not the car's body) Try starting the car. If you have voltage (+12) and the starter doesn't run the problem is with the starter If you don't have voltage, measure between the same heavy wire and the chassis ground . Try starting the car. If you have voltage the problem is a bad ground. Confirm by connecting between the starter ground and the car chassis. If there is voltage you have a bad ground.

A friend of mine wants to give me a 1978 450SL.

Vlad

Out of caution I'd suggest you first convince yourself that the starter is, in fact, the problem. It may very well be given the car's age, but you'd be crestfallen if you replaced the starter only to find no change.

Have you confirmed 12V at the starter when the key is turned to START?

If not, then the other possibilities are: ignition switch, neutral start safety switch, etc.

I'd suspect this car wasn't driven for nine months because nobody could solve the problem.

There's a lot of knowledge in this group, most of it good, so come back with your questions.

There is a ground strap that runs above the battery tray on the firewall to the transmission linkage/dipstick area.Also the ground wire from battery to the fender is suspectable to corrosion.

To remove starter,go under the W123 and use 2 long 3/8 extensions with a 17mm socket and another ratchet or box wrench and remove bottom bolt and then the top.After the starter comes down,you can then remove the wires.Pay close attention when you reinstall the starter and avoid the wiring touching the shield or manifold.

One last thing to consider is checking the connections for corrosion on the little junction that is located on the frame near the alternator and AC.

No way. He mention 2 conditions: a) His wife approval ( she is a good friend ) b) I have to pick it up (about 2000 miles from my place)

The car has 180.000 miles By the way... I am not gay.

Vlad

Thanks for all the help!

Ok I've had the Starter Tested and the Brushes were stuffed!

The Soleniod (Starter relay?) tested fine.

I reinstalled the starter and Finally have her cranking.

Cleaned all the grounds.Checked for corrosion on the power distribution block, cables and wiring

The Fuel pump was also dead! So I Popped a new one of them in too.

I can now hear the fuel pump pressursing the system when turning the key on.

She fired straight away and idled perfectly for about 40 seconds!!!

Then died. I tried starting it again straight away. But she wouldn't fire!

And I couldn't hear the fuel pump running???

Had a bit of a read through the online MB manuals.

And found that the fuel pump relay is located behind the Glovebox.

I disconnected that and tried to start it. The fuel pump worked but she didn't want to crank!!

Reconnected it and the same thing again. Fuel pump on but no crank.

There is 12V at the starter Soleniod (main terminal).

I'm getting a faint click from the small Square relays mounted next to the fuse box

Is one of these another relay for the starting system?

Where is the safety switch located?

Thanks for all the help again( I'm so close).

My plans for the car are new Black paint a nice set of Polished wheels 17 or

18 inch.

The fuel pump safety switch is located in the airflow sensor.If you look at the top of this sensor,you will see an electrical connection(blue) and to change,sadly you have to disassemble but is fairly easy.The 10mm bolts that go around are all that holds the two halves together.The hard part is removing the fuel lines from the fuel distributor. To prevent kinking them,loosen at the injector also! If time and money allow,replace the injector O-rings and sleeves.

Forgot to add:possible causes

Jammed or sticking airflow sensor

Auxiliary air valve sticking

Cols start injector not opening

Defective thermo-time switch

Sticking control plunger

Restricted injectors

Do a volume and pressure test after you get the fuel pump to behave! 75 to 84 psi on the fuel pressure.

Fuel pump relay specs: Place an 8 amp fused jumper between fuel pump relay(on top of front fender under black cover,and is the one closest to the engine and firewall)sockets terminals 30/51 and 87.

If you are interested,I have a W123 forum at yahoo to help you out on top of here;

74 members andthere is one also at msn snipped-for-privacy@groups.msn.com 1400 members

Thankyou for the help Captain.

At the moment the fuel pump is working. But she doesn't want to Crank.

I'm just getting a faint click?