Possible Alternator or ?? Issue Cummins 450 C's

SR400DB

SR400DB

Active Member
Mar 18, 2008
975
Live California; Boat West Coast
Boat Info
2003 400DB, Simrad NSS12, 6100i, Furuno Navtex, KVH M3 Harbormaster Mark II
Engines
Cummins 6 CTA'S 8.3 417 BHP.
Here are my symptoms:

Boat started and ran great this morning. Made a 45 minute run, docked and went into have lunch/hang out. After a few hours went to leave and the port engine would start only using the emergency start switch. As soon as I released the emergency start switch, engine died. (Nothing happened when I just pressed the port engine start switch) After several attempts, I held the switch down for an extended period of time (few minutes at most) and the engine ran fine for our run back to our slip. Once in the slip, shut down engines and same issue with the port engine.

FYI: Belts replaced in January of 2010; new batteries in April of 2010.

So, is this an alternator issue or an electrical issue.

Thanks in advance for any help
 
Either the alternator isn't charging or one of your new batteries has a dead cell in it. Your cross feeding the battery banks to crank and surface charge the dead side indicates either you are not charging the dead side or there is a dead cell running the batteries down.

I'm voting on the alternator.............did you check the voltage on the dead side once you got that engine running?
 
By checking the voltage, at the helm right? Yes, it was reading 13-14 volts, which is just a bit lower than usual (when running). Frank, thanks for the quick response.

So, if this is an alternator (it has never been replaced) any ideas on where to get one? Anyone have the part number handy?

Thanks
 
I would use a digital VOM and check the voltage across the battery bank directly. If your dash gauges are like mine, I have no clue as to the real voltage shown on the Sea ray gauges.

If it were me, I would remove the alternator and take it to an auto-electric shop that rebuilds starters and alternators and have it rebuilt. The case is the "marine magic" here.......the internals are usually just plain Delco parts. The last one I had done cost me $75......was for a Caterpillar 3126. A Cummins replacement is probably going to cost $400-$450, but that is just a guess.
 
I'm guessing your alternator is shot... I had similar symptoms on my port engine a few years ago. A reman (turn in the old one) alternator here at the local Cummins shop was something like $200 and took 10 minutes to install.
 
I guess I was asleep at the switch. Since I have a relationship with a rebuilder, I never considered a factory remanned alternator, but, as Gary and Rick point out, both Cat and Cummins have excellent inventories of remanned parts @ about 1/2 the cost of new.
 
My vote is on the bad battery. I'd check that first as FW suggested.
If you're reading 13-14 volts off the alternator, that's more than adequate to run the engine (provided that's a correct reading).

My stbd alternator has been putting out 12.5 volts for over two years now. Difficult access to pull it, so I've let it be after discussing it with my mechanics. No issues with the engine running or accessories at that output.
 
I agree, I am going to check out the batteries first. If it is the alternator, I will probably track down a reman'd unit and install it. I am thankful it is my port, as my stbd will be a major pain in the a$$ when the time comes.

Thanks for the help!:smt038

tobnpr said:
My vote is on the bad battery. I'd check that first as FW suggested.
If you're reading 13-14 volts off the alternator, that's more than adequate to run the engine (provided that's a correct reading).

My stbd alternator has been putting out 12.5 volts for over two years now. Difficult access to pull it, so I've let it be after discussing it with my mechanics. No issues with the engine running or accessories at that output.
Click to expand...
 
Make sure your battery is dead first. I had similiar problems with mine and it turned out to be the starting solenoid. Literally, it didn't work one second (after replacing batteries AND alternator), then it worked as we jiggled wires on the solenoid to test it.

BTW, the alternator is pretty easy to get off. You can take it in to a rebuild place and they can usually do it in a couple of hours. You end up saving a bunch of $$.
 
SR400DB,

Can you share how this issue was resolved?
 
Just had similar symptoms on my truck 1 month after replacing my battery with a Die Hard Gold. I thought the electrical system in the truck killed the prior battery. Turns out the prior battery was 7 years old and the new one had a bad cell. So, after several weeks of trouble shooting (casually), another new battery fixed the problem.
 
I'd say that's a relatevelly cheap way out, John.

I wonder if SR400DB had to actually get a new alternator or fix the original one.
 
Last edited:
Here is what the issue was:

I did replace the alternator with a new one (about $450)
I had the old one rebuilt (replaced because the rebuild took 3 weeks (parts were back ordered) and I had a cruise scheduled so my loss) (about $190)
Symptoms returned on the 4th day of the new alternator. Swapped the ignition toggle switches to try and see if the problem changed engines. It did (was originally port side, became stbd as soon as switch was changed over)
Bought 3 new toggle switches from flounder pounder. Now she runs great again, has a spare alternator and 2 spare run, start, stop toggle switches in my spared kit. I did switch to the old rebuilt unit when the symptoms returned and am running that alternator for what it's worth.
 
I'm really puzzled how the toggle switch is relevent to the issue of an alternator not charging the batteries. I hope someone can explain the connection here.
 
I don't think it was connected to the alternator issue. Just listing all of the items that were in need of work/replacement at the same time.
 
Got it. Thanks for clarification.
 
SR400DB said:
I don't think it was connected to the alternator issue. Just listing all of the items that were in need of work/replacement at the same time.
Click to expand...

I don't get it (Tom Hanks, "Big.") Seems to me that if the symptoms returned and you swapped the switches P/S, and the problem went with them, then it was the switches. Sounds like the guilty switch had a short and was draining the power.
 
Hampton said:
... Sounds like the guilty switch had a short and was draining the power.
Click to expand...

John,

Whouldn't there be other symptoms? The switch has 3-way function "start-neutral-stop". So, my guess is that if there was a short it should have somehow affect it's functionality or even worst, poor/delayed start or poor/delayed stop.

What you think?
 
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