Cummins 6CTA Wont Start – Starter Issue?

[Gerasimos]

Port Engine wont start. One loud single click/clunk. One time it sounded like there was a pop after the single click one of the times at which point I stopped trying.<br /><br />Troubleshooting I have done:<br />Grounds look OK, I cleaned the main ground on the engine.<br />I tested for voltage for the large red cable that goes to the starter with full time power and its giving me 12.5v so battery to starter doesnt seem to be the issue<br /><br />Some people mentioned the relay, seems like a cheap and easy replacement, but how do I test that appropriately.<br /><br />The engine had no issue starting yesterday. The starboard engine starts right up. in 2021 I replaced the original starter on the starboard. The original is currently still on the port. The engine bank is triple group 31agms shared by both engines, so I don’t think its a battery issue.<br /><br />

 

Video of the click/pop below via youtube

  https://www.youtube.com/shorts/fV7iyGpd4ss   

I cleaned up the connections on the starter itself and on the grounds.<br /><br />I’m getting good power on the heavy gauge POS going to the starter. 13.5v (im plugged into 120 with battery charger on)<br /><br />Still just a single click.<br /><br />I had someone hold the VM when starting, looks like it drops to 11ish volts when attempting to start.<br /><br />Going to clean up all the battery connections just because, but the bank is shared and the other engine fires up no problem.<br /><br />I also tried the emergency interconnect switch to combine both banks, still no start.<br /><br />Interestingly enough, my starter lug gets 13.5v with either the house bank or the engine bank on.

 

 

Topic

[Dave Lincon]

Same – I have a heavy duty interrupt push button just in case it happens again.. always seems to be the port motor which means port side (limited access).

[Gerasimos]

Engine spun freely

 

I was able to get the belt guard off and engine to spin over. Seemed to be harder in some spots, but overall spun freely.

 

Btw without going to start engine, I am getting 13.4 volts at the mag relay “in” and starter “in” but the other two are getting 8v without turning a key. Shouldn’t that read zero volts until I turn a key?<br /><br />Edit as I run through tests.<br /><br />Large POS In on the starter goes from 13.5v to 11.2 when attempting a stsrt<br /><br />Mag relay “in” drops to 11.5<br /><br />Other positive on the solenoid to the starter 11.3v

 

I am wondering if I just replace the starter at this point.

[Gerasimos]

Will be trying this tomorrow. There is just a standard nut for a socket? No need for an adapter? Anything specific I am looking for when doing this? Should there be alot of force required?

[Tony Athens]

The one CLUNK  scares me..

 

Pull off the belt guard and bar your engine over 2-3 full  revolutions  using a 15/16 inch socket on the alternator nut going CW

[Gerasimos]

Thanks Steve, I am scouring through your post history right now to find your write up but cant seem to find it. Summer of 2023?

 

[Steve Lewis]

G,

We had the “Mag Switch” or “Relay” go bad on us on one of our trips.  To test that you can turn on the ignition and then short the two exposed posts on the Mag Switch.  Use a screw driver with a good handle on it.  If it’s the Mag Switch then the starter will engage and spin the engine.  They are inexpensive parts so I replaced both and have one in my spares bin now.  We ended up wiring a cheater switch with some heavy gauge wire and a decently rated push to close switch.  

I wrote a post about it last summer.

[Author]

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