BenzWorld Junior Member
Date registered: Nov 2006
Vehicle: 1976 300d @460k
Location: Ann Arbor, MI
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
i just had similar issues on my 76' 300D.
CHECK your grounds, don't just check them renew them. unbolt the ground from the transmission and get a cordless drill and a wire brush and clean all of the oil and sediment away. Twice. do the same for the connection which attaches to the frame member. also clean up the bolts that fasten them to their individual components.
secondly check to see that the braided copper cable is in good shape and the connections are still solidly soldered in place.
now move up to the battery. check the battery cable connection to the battery post, it must be tight, no wiggle room at all. get out your deep 10mm socket and pull the battery. now to et to the lower grounding point you must remove the battery box. there are two screws fastening the box. one at the 3/4 back and on the passengers side. and another which is accesses from right in front of the radiator.
pull the box and remove the cable. do the same with the rotary wire brush on both sides of the connection point. don't forget any other auxiliary grounds(the 300d has on auxiliary ground there for the fog lights) clean up the bolt and nut on the mating faces/ or replace it. a new cable is inexpensive 4-5 dollars and is well worth it to renew the ground connections.
reassemble. knock as much of the rust, if you have any, from the battery tray and replace it the tray. add an acid neutralizing pad, or a felt pad permeated with baking soda if you have no alternate.reinstall battery.
remember to clean the corrosion off the terminals and also inspect the + positive cable and replace the connection if necessary.
the terminal style where the wire is placed between either side of the clamps and tighten is the least efficient connector. a soldered connection replacement will last a lifetime.
this might not solve all your problems but i'm willing to bet a gallon of Bio that it is the root of many.
check the battery for charge before you reinstall it. a dead battery is really hard on an aging alternator.
try this and come back with your results.
total time one hour