[honest mark]

so my port engine has a very slow rolling start, if i do not use the battery parallel i do not think it will even start, i am the 3rd owner of the boat and have all the service records, the other owners have had similar problems, when i bought boat previous owner had 1 year old batterys  (8) of them, had the slow rolling start so i replaced all batterys, didnt really help much, maybee a little bit, now fast forward 2 years and it's the same thing, my local mechanic does not think it's the batterys, i have checked the batterys, they are clean and tight, if it is not a loose wire is my only option to replace the starter? is there a quick check to see if it is my starter? i have read similar thread subjects about the same problem, i have the cummins mechanic coming out in a couple weeks $$$$$$$$ anyone have a idea what this could be? is there a simple check to see if the starter is working properly?? i have cummins qsm 11 660 hp if this helps, lookin for sum advice or what i should ask the mechanic when he gets to my boat? thanks in advance....

[Misdirection]

Is the cable from the batteries to the port motor longer (further away) than the starboard motor is? If so, you could try adding a second similar sized wire to run in parrarel to help carry the load.

Have you measured voltage at the batteries vs at the starter while cranking looking for voltage loss?

Have you cleaned every connection (and added dielectric grease)?

You could swap starters to see if the problem follows it. That might be a way to test the starter.

Sent from my SM-S901U using Tapatalk

[hiccup]

You need a qualified marine electrician to take a look. The battery cables and connections should be inspected--this includes both + and -. The performance of these cables and connections should be quantified with the use of a meter.

If all cables and connections have been inspected and performance quantified and deemed acceptable, the starter should be removed and brought to a DC electrical shop that rebuilds starters & alternators. They are more plentiful than you might think. There, they can properly test the bendix & starter and repair as necessary.

There is no reason in the world a problem like this should be challenging to solve. Not beating you up, just pointing out that this is a very simple troubleshooting and repair exercise for any qualified tech.

[honest mark]

thank you hicup, no , your not beating me up, i am just HORRIBLE with mechanical problems, the worst, lol, i have cummins coming out at the ed of the month and they will figure it out, thank you

[m.t.bentz]

Mark i have had the same problem with my engines 03 42' open with C12's . i disconnected the original battery cables , taped them up and tie wrap them to the side . Then i ran two new 3/0 battery cables , one for each engine, right from the starting battery's to the starters . it solved my problem , now i can start the engines WITHOUT paralleling to the house battery's .

---

Mark also its not the engine starters having a problem , its high resistance connections ether in the cables or in the battery switches . To prove the point get a length of cable 3/0 with a battery post connection on one end and a ring terminal large enough to connect to the starter on the other end and connect the easiest engine first (probably the starboard one) . Do this first before you get Cummins involved , lot less expense .