Alternator Intermittent?

[Kevin Wilder]

Hi, I have a Cummins 6CTA (450 Diamond – single engine, ~2000hrs, date of remanufacture was in 2019) in my boat and I am having some alternator issues.  The alternator seems to run intermittently. When it runs, it’s strong, producing ~14V, but most of the time – meaning 80% of the time, it doesn’t produce any power. Confirmed with clampmeter on alternator wire, no current produced by alternator 

I have already identified i have the 1-wire delco style. I have also disabled the grid heater as I have researched and found issues with the grid heater sticking on and making it look like the alternator isn’t charging. Disabling the grid heater did not solve the problem. 

I attached a diagram of how the batteries are connected to the alternator. I don’t have an isolator diode between house battery and starting batteries, but i have a switch that I manually turn to isolate the house battery from the starting batteries when the engine isn’t running. 

I am not sure where the smaller red wire is going to, i haven’t had a chance to trace it yet. I do measure 12.x V at this wire, same as what i measure at the battery – assuming it attaches to a battery as a sense terminal. 

I have also tried running the motor with various switch combinations. House battery enabled/Disabled, Both start batteries enabled, Battery 1/2 only, etc. none seem to reliably cause the alternator to start.

Any ideas what may cause this? for lack of better diagnosis, I have ordered a new alternator to replace the existing one. Anything else i ought to check before replacing the alternator?

Topic

[Kevin Wilder]

Resolution

I figured I’d follow up on this in case anyone ever has a similar problem.  I replaced the alternator and it now charges batteries fine. 

Looking for the root cause, I found the alternator to be very oily. the issue ended up being that the steering hydraulic lines are routed right above the alternator, and the lowest point on the line was directly over the alternator. 

This spring i did some work and had to disconnect the steering lines and I had to bleed them. During bleeding I had some ATF overflow at the helm pump that ran down the lines and dripped into the alternator – this seems like the most likely cause of the failure. 

[Kevin Wilder]

Today I measure the forward voltage of the diode and I got 0.6v so that seems to be good. I cleaned and reconnected all the terminals of the alternator and it still wouldn’t work. I’m coming to the conclusion that the issue is internal to the alternator. Hoping the new one is delivered tomorrow

[Kevin Wilder]

4003445RX

I agree it’s hard to read. After talking the picture I tried straightening out the sticker and it caused the part number to rub off.

This is the only part number that matches an existing Cummins alternator and makes any sense given the digits I have.

[Clark Leighs]

I can’t help with your problem  but will point out that part of the part number is unreadable.     To much obscuring it.

 

Write it out and repost it or get a better photo that shows ALL digits.

[Kevin Wilder]

Here’s the part number on the alternator 

[Tony Athens]

What type of alternator

At this point I do not think anyone knows what you have including me.. What not post some pics equal to this quality..

 

 

Cummins Marine Delco Style Alternators – Identification

[Kevin Wilder]

I do not ever run a battery charger while the engine is running. I keep the boat on a battery tender at the dock when I’m not on it but I can go out fishing run dura Bright lights, sound system, ac loads through the inverter etc, to the point where the battery voltage sagged into the 11v range and it still will not charge when starting the engine back up.

 

I have absolutely no way to make it charge or make it not charge. It seems to do it totally randomly, but it certainly doesn’t work more often than it does work. 

Given the lack of an obvious answer on this forum, I’m planning on just replacing the alternator when it arrives

[pwrobert]

Do you run a battery charger while running the engines. Perhaps off a generator. The are self regulating alternators and if no demand they will reduce/shutdown current as I understand it. <br />if your batteries are new or in great shape and you don’t run a lot of 12v stuff normally the current output could be quite low – especially on the house batteries. Start batteries may take a bit to go off. <br /><br />

[Kevin Wilder]

The other 2 options look further away from what i have. I am assuming it’s just that the tach drive and the indicator light aren’t used on this engine installation.

 

 

[Kevin Wilder]

I’ve got a delco style alternator. Cummins part number 4003445RX. Besides the main power terminal, On the back of it is a connector that has a single red wire. It looks like the connector has provisions for additional wires but they are not populated and don’t look like they ever were.

[Tony Athens]

Your diagram picture shows a 3-wire alternator?  

[Author]

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