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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: TheLills1961GM on March 24, 2021, 06:17:18 PM

Title: 6V-71 Starter Troubleshooting
Post by: TheLills1961GM on March 24, 2021, 06:17:18 PM
Hi everyone,

We're seeking some guidance with a starting issue that we're having on our detroit diesel 6V-71.

We've made sure to start it up a couple times a month and drive it in and out of the shop over the last two years, never any issues, always a very strong/quick start.

The Issue:

The other day, someone started it up, turned it off...and now it won't start again.

What We Know:

The batteries are reading 12.5v, the starter switch at the driver seat and the positive terminal on the starter solenoid both read about the same. The engine stop lever is in the "fuel" position. The emergency stop mechanism is in the "run" position.

But all we hear is the starter relay clicking in the engine compartment junction box, with each press of the starter switch.

Any advice on where to go from here would be greatly appreciated!
Title: Re: 6V-71 Starter Troubleshooting
Post by: chessie4905 on March 24, 2021, 06:25:12 PM
Try lightly rapping the solenoid on starter while trying to start.
Title: Re: 6V-71 Starter Troubleshooting
Post by: TheLills1961GM on March 24, 2021, 06:28:24 PM
We did tap it a bit, but not while trying to start it. Thank you, we'll try that.
Title: Re: 6V-71 Starter Troubleshooting
Post by: Dave5Cs on March 24, 2021, 07:28:46 PM
Clean the grounds and re install
Title: Re: 6V-71 Starter Troubleshooting
Post by: Utahclaimjumper on March 25, 2021, 04:37:34 AM
 Corrosion problem for sure.>>>Dan  ( It never sleeps.)
Title: Re: 6V-71 Starter Troubleshooting
Post by: Tedsoldbus on March 25, 2021, 04:57:57 AM
I bought my bus in November and 3 hours later, some of it on very bad road on I-20 that bounced me all over the place, I had it in the driveway. Shut it off. Wife said move it 2 feet closer to the house. I had the same issue as you. Click, click but nada. Called previous owner who said " It ALWAYS started. What did you do to it!!", Hung up on him and tried to looked at what I did wrong. On the trip home, a cable had jumped off one of the 2 starter battery terminals. Lucky for me it jumped completely off the terminal so even a non mechanic like me could troubleshoot it. Since it was already running, it kept running coming home. But then would not start. Even Stevie Wonder could see and fix that. A mechanic I know that works on these old beasts we love told me "Always start at the source and work from there". I expect this may not be your problem and the salty guys are rolling their eyes at me, but....... 
Good luck with it.
Title: Re: 6V-71 Starter Troubleshooting
Post by: luvrbus on March 25, 2021, 06:37:26 AM
Just because a battery is reading 12.5 V, doesn't always mean the battery has enough amps to engage and spin a starter,volt meters are not much good for testing batteries 
Title: Re: 6V-71 Starter Troubleshooting
Post by: ol713 on March 25, 2021, 11:27:54 AM


   Hi;

          If you can,  pull the batteries and take them to a shop to check them out.  A good shop
          will also charge  them for you.  Let us know  how it goes.

                                                             Merle.     ;D
Title: Re: 6V-71 Starter Troubleshooting
Post by: chessie4905 on March 25, 2021, 11:31:22 AM
Measure voltage at battery cable going to starter when in the start position. It may drop to almost nothing if you have a cell connector almost gone. Then check again at starter on both sides of solenoid while in the crank position. If terminal going to inside of starter is next to nothing, pull solenoid. If both are ok, check brushes on starter. They may be next to gone. Before you do all this, locate the source of the click. There may be a relay before the solenoid, like a neutral safety relay or such.
Title: Re: 6V-71 Starter Troubleshooting
Post by: 6805eagleguy on March 25, 2021, 04:03:15 PM
Quote from: ol713 on March 25, 2021, 11:27:54 AM

   Hi;

          If you can,  pull the batteries and take them to a shop to check them out.  A good shop
          will also charge  them for you.  Let us know  how it goes.

                                                             Merle.     ;D

Carquest Napa or similar will normally check batteries for you. But if relay on starter is not clicking then it is a wiring problem somewhere
Title: Re: 6V-71 Starter Troubleshooting
Post by: TheLills1961GM on March 26, 2021, 09:18:47 AM
Quote from: chessie4905 on March 25, 2021, 11:31:22 AM
Measure voltage at battery cable going to starter when in the start position. It may drop to almost nothing if you have a cell connector almost gone. Then check again at starter on both sides of solenoid while in the crank position. If terminal going to inside of starter is next to nothing, pull solenoid. If both are ok, check brushes on starter. They may be next to gone. Before you do all this, locate the source of the click. There may be a relay before the solenoid, like a neutral safety relay or such.

Voltage looked good in those places (12.39v about).

The click is definitely coming from the starter relay inside the engine compartment junction box, not the starter solenoid itself, we don't hear anything happening there.

*Just wanted to say thanks to everyone chiming in and helping us figure this out :)
Title: Re: 6V-71 Starter Troubleshooting
Post by: luvrbus on March 26, 2021, 09:28:13 AM
Some Delco starters have a over cranking device built into the starter buy a remote starter button from Napa or others places or jumper it from the positive to the "S" terminal on the solenoid see if it starts