Starter Troubleshoot Guide

[MoonlightVFR]

0 300 C170B - 950 SMOH

Original starter, solenoid , battery cables, starter motor.

Brand new Concorde Battery - it is hot 12.9 V

Turn Master switch on, hear strong solenoid click engagement.

Pulled Starter cable expecting to see prop rotation. Nothing. Silence. Repeat three times - Nothing .

Had assistant observe cable motion at starter. Two things happen. mechanical arm pushes electric Button switch and thrust gear engagement shaft. Nothing.
Puzzled. Did no trouble shooting. Locked up hanger and came home.
Suspect that voltage not being applied to starter motor. Obvious.

what is first step in trouble shooting this problem? Is there a published starter
trouble shoot list?

Regards

[Bruce Fenstermacher]

Well it's pretty easy. In fact, you've already done some of the trouble shooting.

A quick list how I'd go about it.

1. Check battery voltage
2. Check solenoid energized with master switch turned on
3. Check for battery voltage at positive terminal on starter motor.
No voltage - check #2 again if solenoid is being engaged, solenoid contacts are bad. Clean contact or replace solenoid
Voltage found - go to #4
4. At this point either the brushes in the starter are not making contact with the armature or the starter button contact on the starter is dirty.
a. Remove the starter button. Here is a picture of it:

236565.jpg (8.64 KiB) Viewed 9796 times

b. Flip the starter button over and clean the contacts and check continuity afterwards when engaged with multi meter.
c. Reinstall and test starter.
If starter doesn't turn and your sure the button is making clean contact to the starter motor, your starter motor brushes are not making contact with the armature.
1. Remove starter and inspect brushes. Service starter motor as necessary.

Note: If it's the brushes, finding a way to turn the starter motor shaft to a new position may allow the brushes to make contact and the starter work. But it is a very temporary fix likely to leave you hanging in short time.

If you need to replace the starter button here is a thread with NAPA part numbers. It is a common Delco Remy part:
http://www.cessna170.org/forums/viewtop ... tch#p62601

The Associations Electrical System Manual provides a description on page 10, how the starter system works.
http://cessna170.org/forums/membersOnly ... manual.pdf

[Metal Master]

Bruce you and I must have been typing at the same time!
There is not a published starter trouble shooting guide that I am aware of but this is a very simple system. The system has a drawing and explanation in the Teledyne continental C125, C145 and O-300 overhaul manual X30013. What you do not have one? Look here: http://www.continentalmotors.aero/WorkA ... 2147483690 (edit link added by moderator. You will need a log in which you can get at the same site)

First with the master relay turned on battery voltage should be present at the Starter contactor without the start cable pulled. Check with volt meter. Other possibilities or a bad ground to the engine and or Starter from the airframe (battery)

On the original starter, One wire comes from the Master relay to the starter contactor. Once the Arm on the starter pushes down the button on the starter contactor The circuit is closed to the starter motor and the starter should turn (Run) and the engine should rotate. The arm should have an adjustable bolt & nut on the arm that pushes on the starter contactor. Most importantly, Prior to the Bolt pushing down on the contactor button the end of the arm also pushes in the plunger below the starter to engage the starter with the engine gear train. Without pulling the starter pull cable (plunger not engaged)if you pushed down on the starter Contactor the starter should turn without the engine turning because the starter is not engaged. If you try this be sure the plunger is completely retracted (not engaged). Without the plunger pushed down on the starter engagement and the contactor closed the motor should run without the engine turning. (stay clear of the propeller) If it does not either the starter contactor is defective or the starter is defective. Which could mean the internal wiring is defective in the starter or the brushes are bad. If it starter does turn the starter cable and arm need adjustment per the specs in the Teledyne continental C125, C145 and O-300 overhaul manual X30013. This should probably be checked by an A&P familiar with the system.
Other possibilities or a bad ground the the engine and Starter from the airframe (battery)

[MoonlightVFR]

Thank you Bruce and Metal Master

You have set me on right track

[n3833v]

Sometimes starter brushes will stick in their holders and hitting the starter will jar them loose. It might start to get it somewhere to remove the starter and have it repaired due to the brushes are likely worn so small they need replaced.

John