Starter continues to engage - PeachParts Mercedes-Benz Forum

AlexCole · #1 10-06-2013, 06:41 AM

1980 240D. Over the last week, at startup, I get a short-duration (a second or less) growling sound coming from the engine bay immediately after the engine starts/catches. It doesn't happen at every startup, and there doesn't seem to be a pattern associated with it (that I can discern). I suspect it is the starter continuing to engage the flywheel even after it has started the engine, and what I am hearing is the gears grinding. I have had starter problems in other vehicles before (gassers only), but those cars invariably did not start, rather than continued to start.
First off, am I on the right track here? Next, Is there a solenoid associated with this starter, and if so, is this more or less likely to be the culprit? In the gassers I have worked with, the solenoid is a $10 part that is rebuilt in a third world country that might be bad right out of the box.....thanks in advance.

pimpernell · #2 10-06-2013, 07:48 AM

Quote:

Originally Posted by AlexCole

1980 240D. Over the last week, at startup, I get a short-duration (a second or less) growling sound coming from the engine bay immediately after the engine starts/catches. It doesn't happen at every startup, and there doesn't seem to be a pattern associated with it (that I can discern). I suspect it is the starter continuing to engage the flywheel even after it has started the engine, and what I am hearing is the gears grinding. I have had starter problems in other vehicles before (gassers only), but those cars invariably did not start, rather than continued to start.
First off, am I on the right track here? Next, Is there a solenoid associated with this starter, and if so, is this more or less likely to be the culprit? In the gassers I have worked with, the solenoid is a $10 part that is rebuilt in a third world country that might be bad right out of the box.....thanks in advance.

could it possibly be a weak Bendix spring??

The Bendix system places the starter drive pinion on a helical drive spring. When the starter motor begins turning, the inertia of the drive pinion assembly causes it to wind the spring forcing the length of the spring to change and engage with the ring gear. When the engine starts, backdrive from the ring gear causes the drive pinion to exceed the rotative speed of the starter, at which point the drive pinion is forced back and out of mesh with the ring gear.
The main drawback to the Bendix drive is that it relies on a certain amount of "clash" between the teeth of the pinion and the ring gears before they slip into place and mate completely; the teeth of the pinion are already spinning when they come into contact with the static ring gear, and unless they happen to align perfectly at the moment they engage, the pinion teeth will strike the teeth of the ring gear side-to-side rather than face-to-face, and continue to rotate until both align. This increases wear on both sets of teeth.

Diesel911 · #3 10-06-2013, 12:19 PM

His Starter has an Overrunning Clutch type Starter Gear.
Mechanical issues that can cause it to stick out are worn Bushing, worn overrunning Clutch, deformed Metal Burrs on the Ring Gear and if the Solenoid Linkages are all gummed up with dried lubricant.

A Bosch Solenoid is not $10.
Electrical issues.
For the Starter to say engaged the Solenoid would still have to be getting Voltage When the Key is off. You can check that with a Test Light or volt meter. The problem will be duplicating the symptom.

I can't think of a particular reason the Solenoid Plunger would not return if it is not getting Voltage; unless there is an issue with the Spring or the Plunger has crud on it.

The Starter Motor is similar to an AC Delco Starter from the 1970s and backwards. See the pic

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