Official Cummins 6cta 450C thread

ttmott said:
The issue that can happen is if the diodes in the rectifier circuit allow current to flow in the wrong direction. Diodes are electrical "check valves" for lack of a better description, current can flow one direction but not the other. They can fail Open or Shorted. If they are shorted then current will flow from ground to the battery positive and will discharge the battery. You can usually tell as the back of the alternator gets hot to the touch when not running.
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Thanks, will do some checking this afternoon.
 
Ugh, checked the output at the alternator yesterday and nothing. Alternator lasted about 18 months. It would also be the starboard one which is a pain to get to.
 
Irie308 said:
Ugh, checked the output at the alternator yesterday and nothing. Alternator lasted about 18 months. It would also be the starboard one which is a pain to get to.
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If it makes you feel any better, both of mine are not working again. I had them rebuild around this time last year. I’m wondering if it’s because I kept my battery charges on when I start the mains and when running the Gen(and charges) underway.

Anyone got a part number on the diode and brushes?
 
saopm said:
If it makes you feel any better, both of mine are not working again. I had them rebuild around this time last year. I’m wondering if it’s because I kept my battery charges on when I start the mains and when running the Gen(and charges) underway.

Anyone got a part number on the diode and brushes?
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I leave my charger/converter on all of the time and I still have the original charger and replaced one of the original alternators at 2800 hours 2 years ago. I blame early alternator failure on these motors on the intake air heaters as long as everything else is working properly. Just my opinion, ymmv.
 
my3sons said:
I leave my charger/converter on all of the time and I still have the original charger and replaced one of the original alternators at 2800 hours 2 years ago. I blame early alternator failure on these motors on the intake air heaters as long as everything else is working properly. Just my opinion, ymmv.
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I did same on the 6CTAs and QSCs...never and issue.

Bennett
 
Removed my grid heaters the same time i replaced alternators for fear of that same issue. Chalking it up to cheaply made product. My shop won't even entertain rebuilding it as he says a replacment is about $190.
 
saopm said:
If it makes you feel any better, both of mine are not working again. I had them rebuild around this time last year. I’m wondering if it’s because I kept my battery charges on when I start the mains and when running the Gen(and charges) underway.

Anyone got a part number on the diode and brushes?
Click to expand...
What alternator do you have? Delco 20SI? The number is cast on the back of the case.
Regardless there is a rash of foreign (Chinese) repair parts that do not meet Delco's specifications.
If you had them rebuilt and they threw cheap Amazon parts into them, then no doubt there will be failures.

Here is a test tidbit - measure the output voltage first on the alternator then separately on the house charger/converter using a good DVM set on AC voltage. If you are seeing AC (ripple) voltage greater than 5 millivolts the charging device is defective. If that ripple is significant it can take out other charging devices.
AC ripple is caused by the bridge rectifiers breaking down and not outputting pure DC current.

Here are some Delco P/N's -
Regulator - 1116045
Rectifier - 1984638
Diode Trio - 10517359
 
ttmott said:
What alternator do you have? Delco 20SI? The number is cast on the back of the case.
Regardless there is a rash of foreign (Chinese) repair parts that do not meet Delco's specifications.
If you had them rebuilt and they threw cheap Amazon parts into them, then no doubt there will be failures.

Here is a test tidbit - measure the output voltage first on the alternator then separately on the house charger/converter using a good DVM set on AC voltage. If you are seeing AC (ripple) voltage greater than 5 millivolts the charging device is defective. If that ripple is significant it can take out other charging devices.
AC ripple is caused by the bridge rectifiers breaking down and not outputting pure DC current.

Here are some Delco P/N's (there are no brushes in a 20SI) -
Regulator - 1116045
Rectifier - 1984638
Diode Trio - 10517359
Click to expand...
They can always do what I did 9 years ago when I had one fail. Buy a brand new 22si / 160amp alternator from Seaboard Marine. Best alternator I ever owned. I paid $450 for it then. It’s now $995. Gulp! At least you know it’s built to Tony’s specs and will last.
 
ZZ13 said:
They can always do what I did 9 years ago when I had one fail. Buy a brand new 22si / 160amp alternator from Seaboard Marine. Best alternator I ever owned. I paid $450 for it then. It’s now $995. Gulp! At least you know it’s built to Tony’s specs and will last.
Click to expand...
I bought seaboard‘a also. We were cruising Lake Superior and all I could find on line was remanned stuff that I didn’t trust. I had Tony’s guys send one to a marina in Munising Michigan and we just ran for a few days with the gen running and I could accurately watch the voltage On my garmin plotter. When we got to Munising it was there waiting for us.
I had the dead one rebuilt by an auto electric guy I’ve know forever who only uses the best parts and it’s under the floor waiting for the other one to crap out.
 
ttmott said:
What alternator do you have? Delco 20SI? The number is cast on the back of the case.
Regardless there is a rash of foreign (Chinese) repair parts that do not meet Delco's specifications.
If you had them rebuilt and they threw cheap Amazon parts into them, then no doubt there will be failures.

Here is a test tidbit - measure the output voltage first on the alternator then separately on the house charger/converter using a good DVM set on AC voltage. If you are seeing AC (ripple) voltage greater than 5 millivolts the charging device is defective. If that ripple is significant it can take out other charging devices.
AC ripple is caused by the bridge rectifiers breaking down and not outputting pure DC current.

Here are some Delco P/N's (there are no brushes in a 20SI) -
Regulator - 1116045
Rectifier - 1984638
Diode Trio - 10517359
Click to expand...
The casting says 22SI. I’ll have to check the charger as you described. It seems strange for both of them to go at the same time, so maybe it is the charger.
1693626623958.png

1693626656990.jpeg
 
saopm said:
The casting says 22SI. I’ll have to check the charger as you described. It seems strange for both of them to go at the same time, so maybe it is the charger.
View attachment 150279
View attachment 150280
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22SI is a good alternator - same on my boat.
There are rotor brushes - I mis-stated earlier.
The B plus wire is probably routed from the alternator to the engine starter battery positive lead rather than directly to the battery. This can lead to a bad situation should the battery(s) be switched off when the engine is running. It will most likely take out the rectifiers in the alternator due to a voltage spike when the alternator disconnects from the load.
Loss of both alternators seems to be a case of the batteries being switch off with engines running. The only other thing would be the charger/converter acting up but the batteries would also suffer. Do the ripple test with your DVM.
As long as the charging systems are in good working order there is nothing wrong with leaving them all on charging a single battery. They will all self regulate. Multiple alternators on a single battery is a bit different as they will, for lack of a better term, compete for charging and voltages/currents will vary.
 
Had a weird issue this weekend. Boat fired right up Sunday, but went to crank up Monday and the port engine tried to crank and then the solenoid started clicking like the battery was dead. It wasn't, with charger off sitting 12.7 and dropping off about 1.5 volts during crank. So, I got out the meter and checked and voltage was good all the way to the starter. Jumped just the starter motor, spun well, jumped the the starter and solenoid, same issue. Took all the connections off and cleaned, same issue (of course it was on the engine that was hard to get to). After multiple tests, I noticed one of the bonding wires smoking. Turns out, corroded main ground on the engine and the electrons tried to flow back through the bonding system, which clearly can't handle that kind if amperage. Cleaned the ground, problem solved. Also, cleaned the ground on the other engine in hopes of not having that issue again.

Maybe this will help someone else one day. I could have saved our day on the water, a bonding wire, and a bunch of troubleshooting by just cleaning the ground first.
 
Forrestkk said:
Had a weird issue this weekend. Boat fired right up Sunday, but went to crank up Monday and the port engine tried to crank and then the solenoid started clicking like the battery was dead. It wasn't, with charger off sitting 12.7 and dropping off about 1.5 volts during crank. So, I got out the meter and checked and voltage was good all the way to the starter. Jumped just the starter motor, spun well, jumped the the starter and solenoid, same issue. Took all the connections off and cleaned, same issue (of course it was on the engine that was hard to get to). After multiple tests, I noticed one of the bonding wires smoking. Turns out, corroded main ground on the engine and the electrons tried to flow back through the bonding system, which clearly can't handle that kind if amperage. Cleaned the ground, problem solved. Also, cleaned the ground on the other engine in hopes of not having that issue again.

Maybe this will help someone else one day. I could have saved our day on the water, a bonding wire, and a bunch of troubleshooting by just cleaning the ground first.
Click to expand...
Well done. I had similar main ground issue when I bought the boat 10 years ago. Took a lot to break the suspect ground bolt off. Cleaned all the cables bolted on and bought a new bolt. Then proceeded to remove and clean all the main engine grounds (they are on both sides of the engines - some include aftercooler brackets). I now break the bolts free and make sure everything is good once a year when I do all the manual maintenance. I do the same with the four mixer to turbo bolts, on each engine.
 
ZZ13 said:
Well done. I had similar main ground issue when I bought the boat 10 years ago. Took a lot to break the suspect ground bolt off. Cleaned all the cables bolted on and bought a new bolt. Then proceeded to remove and clean all the main engine grounds (they are on both sides of the engines - some include aftercooler brackets). I now break the bolts free and make sure everything is good once a year when I do all the manual maintenance. I do the same with the four mixer to turbo bolts, on each engine.
Click to expand...

It is going on annual maintenance from now on, for sure!
 
ttmott said:
What alternator do you have? Delco 20SI? The number is cast on the back of the case.
Regardless there is a rash of foreign (Chinese) repair parts that do not meet Delco's specifications.
If you had them rebuilt and they threw cheap Amazon parts into them, then no doubt there will be failures.

Here is a test tidbit - measure the output voltage first on the alternator then separately on the house charger/converter using a good DVM set on AC voltage. If you are seeing AC (ripple) voltage greater than 5 millivolts the charging device is defective. If that ripple is significant it can take out other charging devices.
AC ripple is caused by the bridge rectifiers breaking down and not outputting pure DC current.

Here are some Delco P/N's -
Regulator - 1116045
Rectifier - 1984638
Diode Trio - 10517359
Click to expand...
I checked the VAC of the output side of the house charger. The meter read 29.3 on the VAC 200m scale. Alternators are not functioning. It seems the charger is the the problem, no?
 
I think I mis-stated the allowable ripple - Should be no greater than 50 mV (0.05 Volt) - I stated 5 mV which is incorrect.
Let's see - DVM scale is 200mV right? So full scale is 0.2 volts.
29.3 mV is 0.029 volts AC on the DC circuit.
That is about 0.03 volts AC ripple which is less than 0.05 maximum.
Based upon this your Charger is OK.
 
This would be my 4th pan heater on my port motor in 3 years. Two of them were purchased from Seaboard and 1 from Amazon. I originally purchased a pair from Seaboard the starboard one still works but seems the port dies after a few weeks. They are the 250 Watt pan heaters plugged into the same circuit. Am I crazy for wanting to buy a 4th to see if I will have different results. I can't figure out why they keep dying. I've made sure I followed the installation directions to the letter. I've removed my grid heaters so just trying to add some warmth to the blocks as we boat into early November.

https://www.sbmar.com/product/wolverine-oil-pan-heater-model-25/
 
How well do they work and are they hard to remove to replace? Do you leave them on full time, or shut them off when you are gone for the week? Even with grid heaters, it’s a bit smoky when I start on a cold November morning.
 
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