Sounds more like a problem with the bendix unit.
The solenoid is a magnetic switch mounted on top of the starter motor. It
has two important functions: it controls the electrical circuit between the
battery and starter motor and it can be used to shift the pinion gear in and
out of mesh with the ring gear.
The bendix drive depends on inertia to provide meshing of the drive pinion
with the ring gear. The screwshaft threads are a part of the armature, and
will turn at armature speed. At the end of the pinion and barrel is the
pinion gear that will mesh with the ring gear. The pinion and barrel have
internal threads that match those of the screwshaft. When current flows
through the starter motor, the armature will begin to spin. Torque from the
armature is transmitted via a shock-absorbing spring and drive head to the
screwshaft. This causes the screwshaft to rotate. However, the barrel does
not rotate. The barrel has a weight on one side to increase its inertial
effect. The barrel tends to stay at rest, and the screwshaft rotates inside
the barrel. As a result, the barrel is threaded down the length of the
screwshaft to the end. At the end of the screwshaft, the pinion gear engages
the ring gear. Here the pinion gear locks to the screwshaft and transfers
torque from the armature to the ring gear and engine.
Once the engine starts and is running under its own power, it will rotate
faster than the armature. This causes the barrel to screw back down the
screwshaft and bring the pinion gear out of engagement with the ring gear.
It sounds like your bendix unit is dirty or damaged. The high pitched sound
is likely the starter motor whirring with no resistance(no engagement).
Try pulling the unit and bench test it in a strong vice. (DO NOT apply
power to an unsecured starter motor.) You should be able to observe the
action of the bendix (or inaction), If it's just dirty . clean it up and
test again befroe reinstalling. If it's worn, still binding etc. Replace the
unit. Call around for prices on exchange rebuilt units from places that
spcialize in auto electrical.
All of this talk about starter solenoids has gotten me
thinking about a problem I've been having with my 1974
Here's the description: For some months now when I
first start my car I sometimes hear a horrible
grinding noise coming from the starter area. It
sounds like the gears are not meshing together like
they're supposed to. It's not steady and low level
but a fast, high pitched spinning noise that goes
right away. The car obviously does not turn over at
this time. After another hit or two of the key it
usually does not happen and the car turns over and
It's now getting more frequent and pronounced. Is
this the starter going bad or it something else? Just
what does the solenoid do anyway? Thanks.
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