PeachParts Mercedes-Benz Forum - View Single Post - Electrical gremlin, possible bad starter, help!

JimSmith · #2 07-05-2002, 01:13 AM

rickjordan,

There can be a number of items affecting your starting. First, I would check the major power connections to make sure they are clean and not unnecessarily dropping Voltage. These would be the ground connection from the negative terminal of the battery to the right front fender. The bolt there has to have a good, clean seat on the the wire connector. Next, both terminals from the battery. Then, the connections to the starter. These tend to be less apt to corrode as they are made of similar metals. The other connections are not, and there will almost always be some form of galvanic corrosion at each of them over time.

Next I would check the Voltage across the battery with the motor off, no accessories on, no doors open, etc. You should have 12.5 Volts or more. Then with the car running at idle, you should have 13.6 Volts or more.

If the battery is low, see if the running Voltage is low too. That would indicate a poorly performing alternator or Voltage regulator.

With the battery in marginal condition, running the glow plugs can draw the battery down so starting it won't get all the Voltage it needs. The next time around, the glow plugs may not get the same glow period and the battery may be able to restore itself enough after the brief rest to just get the starter to run.

With the hood up have someone else turn the key to start and make sure the click you hear is really coming from the starter solenoid. A stethescope for isolating car noises might be helpful.

Once you have confirmed the starter solenoid is making the clicking sound, do it while you measure Voltage across the battery to see if the starter motor is actually getting any current. This will also be apparent if the interior overhead light is on and it dims when you hold the key in the start position. If the solenoid is sticking or not healthy it can stop short of activating the starter motor. If the starter motor is getting juice and not responding it is likely a worn out starter. This does not explain the phenomena of the willingness to start the second try as most illnesses of the motor will not get better the second time around.

So, I would suspect either a marginal battery, or a bad solenoid. The second attempt success may be a result of the clicking, evidence of the solenoid hitting something and possibly knocking it partially out of the way or something so the second attempt is less demanding and works.

Hard to say anything for sure, but there have been threads on bad dash switches, meaning the starting switch the key goes into that you turn to start the car. I have a hard time actually believing this could explain your situation as the key switch merely activates the solenoid, not the starter motor directly. The solenoid activates the starter motor when it gets to the end of its stroke and the pinion gear is engaged in the ring gear on the flywheel.

Hope this helps, and good luck, Jim