PeachParts Mercedes-Benz Forum - View Single Post - diagnosing dead starter motor? '84 300TD Benz

Diseasel300 · #7 08-08-2017, 11:47 AM

Batteries can be a source of great frustration. Just because they show voltage doesn't mean they can deliver adequate current. If the battery is old and the plates worn or sulfated, it will struggle to start a diesel.

Testing the starter motor correctly is important as it can cause you to pull the motor thinking it is bad when it really isn't. The solenoid does 2 functions: it throws the bendix assembly into the flywheel to allow the motor to turn the engine and it also closes a set of contacts to cause the motor to run. A bad solenoid can still operate the bendix, but fail to close the contacts, usually indicated by clicking when turning the key, but no starter engagement, but eventual starter operation after a few tries.

Jumper cables aren't always a reliable test either. A good set of jumper cables will be a minimum of #6 wire, but preferably #4 or larger with a high quality (heavy) clamp. Good jumper cables aren't cheap and cheap jumper cables aren't good. The pathetic flimsy #8 cables they sell at Wal-Mart and most people carry in their cars will struggle to start a Corolla, you can forget about them starting a diesel of any variety.