QuestionQUESTION: my car will not start the battery, the alternator, the starter had them all tested at a o'rielys auto parts (battery and alternator) and napa (starter) all came back good but i can only get one good crank on the battery before its to weak to do any thing
ANSWER: Hello Jeremy,
You did not mention if the engine begins immediately on the fresh battery, or does it require several moments to get it to fire off.
Diesels by nature, because of their higher compression, require more starter torque to get the engine to turn over. In many cases, two batteries are used in parallel to maintain the amperage during the cranking process.
You probably need to determine it the alternator has an internal voltage regulator or not. I suspect that if the voltage regulator is external, often the case on earlier cars, the voltage regulator is bad. I had a similar incident with my dodge van. Alternator checked OK, but battery would not stay charged. The voltage regulator was bad, and when I replaced it the battery stayed charged.
Also, sometimes if the alternator has a bad rectifier it will allow the battery to drain back to ground when the vehicle sits over time. It is as if you left a light on in the trunk etc.
If the regulator is OK. Then I would suspect a bad ground, or positive wire looseness. The main ground strap and any where else the main cable connect, need to be removed and cleaned thoroughly as do the frame area where they connect particularly if there is rust present. Rust become an insulator and must be removed.
If you do not have good clean terminal ends on the battery or any where else, a high resistance will not allow the proper flow during charging and also during the starter run on cranking.
Please let me know what your find out.
Rob
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QUESTION: where is the voltage regulator located and were is all the main grounds located is there pic of these
ANSWER: Jeremy,
The voltage regulator may be on the fender well or firewall if it is not internal to the alternator.
I have no pictures relating to this vehicle. You may be able to google the vehicle for manuals on Ebay or one of the Mercedes sites like benzworld.com.
Look for a large sometimes braided flat strap between the body and the starter or block.
Also, your starter may be ok during a free float test on the bench. However, if you have worn bearings in the starter, under load, the armature can drag the field winding and cause such high resistance that it will over tax the battery, particularly if it is not a new battery.
Is the starter just clicking when you turn the key. Make several attempts to get it to start in this condition.
turn of the key and feel of the starter terminals and each place the main cables attach to see if they are hot. Heat indicates a high resistance just like in your oven at home.
A clear sign that the connection need to be separated and cleaned.
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QUESTION: well i didn't see a breaded cooper wire any where but i cleaned both the ends of the battery ground and positive and the starter wires that go to the battery and a little red wire witch i believe to be a ground. fixed a in line fuse that from the positive post of the battery to a little silver box witch in turned split off and has wires running to the radiator fan and to a calendar shaped thing with wire terminals and runs back out that runs back in to the fire wall that cilender sits into a black container with a tube like for air or liquid could run throw and a another that ran to the a/c pump but i unplugged that cause i have no blet on it and a/c. i cleaned the wire ends and fixed the one end of the ground that connects to the back of the alternator i have also put a new fuel filter and prefilter on and toke the fuel filter housing apart detached the fuel lines and cleaned every thing with diesel fuel like the book said to do i put every thing bake together and opened the bleeding valve and pumped closed it and pumped till i heard a buzzing sound. now i have put the battery in the car strait off the charger and and tryed to turn over the car nothing tryed a couple of times then i put the charger on the battery still hooked up to the car put it on a 2amp charge and left for a bit came back and switch the charger to assist start went to try to start the car barely wanted to turn over neither times did it start when i hooked my battery up to the car it had 12volts after i put it in the car and tryed to start it had only 8volts
AnswerJeremy,
It sounds like you are on the right track to get all the ground points cleaned.
How old is your battery? Did you allow the glow plug light to go out before attempting to start the engine?
What size charger are you using?
The battery should be at least 600 cranking amps, and usually needs 30 amps at about 13 volts to really get it to full.
I get the impression that the battery is not supplying enough amperage to really spin the starter.
Rob
