You turn your key and nothing happens. Your headlights work, your interior lights are bright.
Your dash lights seem bright and normal. What the heck? So you go back into the house and get your buddy who works on cars.
He tells you to sit in your car and hold the key all the way over to the right in the start position.
Then he gets a screwdriver (or some small tool) and crawls under your car. In about a minute,
your car is cranking and the engine fired up.
“ What did you do ?” you ask him. “ I tapped on the starter, you have a dead spot. ” What the heck is a dead spot is going through your mind the whole way home. After you make it home (thankful for not having to call a tow truck) you shut the car off, and try the starter just for curiosity. It seems to work fine now. Even started 3-4 times without a hitch.
Doesn’t make sense, so you kind of shrug it off. Next morning : DEAD SPOT. No matter how many times you turn the key, she ain’t goin’ nowhere. Hitch a ride to work and deal with it later.
There are several causes for a dead spot in the starter. One of them is NOT the solenoid. Many well intended people will say it’s the solenoid, because the solenoid’s job is to pull in the bendix and put juice to the starter. They are wrong. That IS the solenoid’s job, but a solenoid won’t pull in the bendix until the starter is functional.
The most common cause of a dead spot is brushes. Brushes can fail from usage, or brushes can fail from oil or antifreeze pollutants. When a trained starter specialist opens up the starter he views the brushes as an odometer. Brush wear is a tell tale sign of how many miles are on a starter.
When the + brushes don’t make contact on the commutator, the pull in circuit in the solenoid can’t get a ground, because it gets its ground through the hot brushes, the commutator on the armature, then the ground brushes on the commutator to the case of the starter. All starters whether permanent magnet or copper wound fields are set up like this. If any of this circuit is open, it would be like trying to start your car without the battery ground cable hooked up.
Another cause of a dead spot can be the starter was previously overcranked. If a car won’t fire because of some ignition or fuel malfunction some people will just hang on the key, crank.. crank.. cranking till the armature is burnt up. If your car won’t fire in 10 seconds or less, stop cranking and let the starter cool down for a period of 1 minute before trying again.
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Corroded starter mounting (external corrosion) causes the exact same symptoms as a dead spot. The most common place for this to occur is the main (biggest) solenoid hot post where the battery cable attaches with lock washers to the solenoid. You can even tap on the starter and it will kick off while someone is holding the key, which leads many mechanics to believe the starter has an internal dead spot.
However, in most cases, if you were to tap on the side of the starter while closely observing the solenoid connection bolt, you would notice a spark. When you see a spark, you know you have a bad connection which is normally caused by the lockwasher. In most cases, by the time you notice a problem, it’s already too late.
Lockwashers can be used, but only if maintained with periodic white lithium grease and initially installed with a generous amount of white lithium grease. As starter rebuilders for the last 4 decades, we have never and will never support the use of lockwashers as part of an electrical connection. Here’s why. See Lockwashers.