8.3 cummins crank up

ric992

ric992

Member
Apr 5, 2021
147
Miami Beach
Boat Info
2007 Sundancer 48
Engines
Cummins QSC 8.3
One of my engines is turning over longer than usaul to start. Any suggestions besides battery? Only probably 2 seconds but enough to definitely notice
 
Did you try using the emergency switch that ties the two batteries together to see if there was a difference? Also, as first "guesses" or detective work, is the Racor clean on the engine in question?

Jaybeaux
 
You are not going to get a lot of answers if you don’t let us blame the batteries… @Jaybeaux brings up a good point with the emergency switch to see if a difference….. then you have starter speed and fuel delivery
 
A friend was chasing slow turning issue for a while. Turned out to be bad ground. If you see no improvement using the emergency switch, I'd check the ground before going the starter route.
 
I was taught to always use the emergency switch to start these motors. They need juice.
 
spikedaddy99 said:
I was taught to always use the emergency switch to start these motors. They need juice.
Click to expand...
Would that depend on the type of battery banks you have?

I have 5 batteries in 2 banks. The engine bank is 3 Group 31 AGM starting batteries. These normally power the high draw items like the engine starter, windlass, and thrusters. Plus a few others.

The house bank is 2 4D AGM deep cycle batteries. These are for most of the 12v low draw loads including lights, 12v outlets appliances and the inverter.

I can combine them via a Bluesea ACR switch, but I would expect regularly hitting the deep cycle batteries with high draw loads would not be great for them.
 
Brad, my motors each have an 8D, so the switch combines those 2. I can't speak to your situation. Interesting set up.
 
Is it that the engine is spinning slower (starter) than the other? I am reading your message as it takes longer to start. I know voltage can play a role in starting beyond the starter. I have Cummins QSM-11's and my starboard engine takes slightly longer to start and has been like that since I purchased the boat a year and a half back. Is it that the starter is spinning slower, or it takes longer for it to fire?

Vince
 
spikedaddy99 said:
I was taught to always use the emergency switch to start these motors. They need juice.
Click to expand...

If you always do that, how will notice a symptoms when something is off? This thread is a good example.

With everything in the right working order, dedicated batteries for each side should be adequate, as per design.
 
Alex F said:
If you always do that, how will notice a symptoms when something is off? This thread is a good example.

With everything in the right working order, dedicated batteries for each side should be adequate, as per design.
Click to expand...
Agree, that is why the button is labeled "emergency". I can see using it if you have a known problem and you are going to fix it in the near future, I am on board with that.
 
Conversely to @LattitudeAdjustment my Port is slower cranking; it always has. But that is the "house" battery (8d).
I didn't realize until I installed a battery monitor system that there are quite a few loads on that battery during cranking (camera system, audio system, boat's lighting, water pump, heads, safety monitors, and on and on). Sometimes I even get a low voltage warning on the Vessel View during cranking. Even with everything switched off there is still a 35W draw on that bank per my Victron Cerbo monitor. But it always starts....
If I have the entire helm up and running (NMEA 2000, MFD's, radio, AIS, Maretron system) the starting of the Starboard engine will sometimes reboot the MFD's; so I always start before turning on the helm stuff.
My 8D's (one port and one starboard) are two year old AGM's.
I suspect also the battery charger isn't up to maintaining the batteries so I'm in the process of correcting that with a 70 amp unit.
I suppose that pressing the Emergency Start could be routine and would correct the inconveniences but I'd rather fix the root causes.
 
+1 on the House battery syndrome. I measured current draw on that side and was surprised to see so much current being drawn. About 300 mA when all the DC breakers are off. But I too have some outboard gear that explains that draw. The previous owner upgraded the A/C converter with a decent output.
Always enjoy reading your replies. Clear concise, useful information.

Vince
 
spikedaddy99 said:
Brad, my motors each have an 8D, so the switch combines those 2. I can't speak to your situation. Interesting set up.
Click to expand...
My setup may be a little different from yours in part because I have a single motor, where you have twins.
 
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