Official Cummins 6cta 450C thread

Currently underway returning from a trip on one motor. Was running at 2200 rpm then alarm and zero oil pressure on port motor. Not getting a reading on the block gauges either. Oil is quarter way into the hash on the dipstick. Any ideas?
 
Currently underway returning from a trip on one motor. Was running at 2200 rpm then alarm and zero oil pressure on port motor. Not getting a reading on the block gauges either. Oil is quarter way into the hash on the dipstick. Any ideas?

That doesn't sound good.
 
Install a mechanical gauge in the galley or filter housing and test. Possibly just a bad sending unit. If not, then I'd say the pump is shot, but usually that's pretty uncommon.
 
Was thinking pump as well but curious as to how it’s energized when you flip the start button. Possible connection issue energizing the pump?
 
Currently underway returning from a trip on one motor. Was running at 2200 rpm then alarm and zero oil pressure on port motor. Not getting a reading on the block gauges either. Oil is quarter way into the hash on the dipstick. Any ideas?
You have three oil pressure sensors on each engine. One is the gauge at the helm. The second is a gauge mounted on the engine right in the middle. The third is a no pressure sensor connected to the System Monitor That sounds an alarm. If you get low pressure from any two of those three, you've most likely truly lost pressure. I've lost one before and it was only a broken sender wire.

Did the alarm sound and zero pressure reading while the engine was running? Or did the alarm sound and oil pressure gauge go to zero because the engine shut down?
 
You have three oil pressure sensors on each engine. One is the gauge at the helm. The second is a gauge mounted on the engine right in the middle. The third is a no pressure sensor connected to the System Monitor That sounds an alarm. If you get low pressure from any two of those three, you've most likely truly lost pressure. I've lost one before and it was only a broken sender wire.

Did the alarm sound and zero pressure reading while the engine was running? Or did the alarm sound and oil pressure gauge go to zero because the engine shut down?
I shut the motor down. The alarm sound and I saw a zero reading at the helm and on the one mounted to the motor.
 
Ok, so back at the dock. I took of the mechanical gauge at the motor and fired up the motor and oil shot out. Put the gauge back on and now both gauges are showing pressure with no alarm.
 
Something still doesn't sound right. How could you have all sending units fail at the same time?
 
Something still doesn't sound right. How could you have all sending units fail at the same time?
They most likely didn't. He probably actually temporarily lost oil pressure. Maybe oil pressure release valve got stuck open (i am guessing there is one) or sump pickup screen got clogged (I am guessing there is one). As you can see I just have guesses.
 
They most likely didn't. He probably actually temporarily lost oil pressure. Maybe oil pressure release valve got stuck open (i am guessing there is one) or sump pickup screen got clogged (I am guessing there is one). As you can see I just have guesses.

That's where I'm going. I definitely would recommend doing some more digging on the issue and maybe phoning a Cummins tech.
 
A friend and a dock mate both suggested a possible issue/restriction in the oil filter. Spoke to my Cummins guy who is on vacation and he reiterated what most have said and that’s the oil pump is fairly bullet proof. He thinks possibly a problem with the pickup. Again some sort of restriction. Will definitely investigate further. First plan is to change oil and filter for now and sea trial.
 
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Quick update: Added about 4 hours to the motors this weekend and the oil pressure didn't skip a beat. I'm leaning towards either an issue with the oil filter or some foaming in the oil due to higher oil level in that motor (about 16-17 qts). Still have the old oil filter and plan to cut it apart to examine. Also sent off a sample so waiting to hear back on that.
 
Hi all, looked at a nice 04 420DA today with a pair of 6CTA 450's. Engines look very clean and have maintenance history, one owner, overall appear well taken care of. Two things stood out to me I'd like your opinion on:

  1. The stern facing section of the engine where what I believe is the belt cover had a little bit of fine black 'spray' on the engine. This was on both sides. I know at some point I've read something about dampers on these engines but I'd think thats on the v-drive side, or could it be worn belt material?
  2. The exhaust manifold where it attaches to the head - what looks like surface rust on the manifold exhaust passages (not the head). Its about the only place I see rust on the engine, and the boat has never been in salt. Maybe its just the iron surface rusting over time, anyone else see anything like that on their engines?

If we move forward a certified cummins tech is lined up for a full day of engine surveys but these were a few things I immediately noticed. That, and surprisingly how much room you have to move around them in a 420 - the ER hatch is huge!
 
Hi all, looked at a nice 04 420DA today with a pair of 6CTA 450's. Engines look very clean and have maintenance history, one owner, overall appear well taken care of. Two things stood out to me I'd like your opinion on:

  1. The stern facing section of the engine where what I believe is the belt cover had a little bit of fine black 'spray' on the engine. This was on both sides. I know at some point I've read something about dampers on these engines but I'd think thats on the v-drive side, or could it be worn belt material?
  2. The exhaust manifold where it attaches to the head - what looks like surface rust on the manifold exhaust passages (not the head). Its about the only place I see rust on the engine, and the boat has never been in salt. Maybe its just the iron surface rusting over time, anyone else see anything like that on their engines?

If we move forward a certified cummins tech is lined up for a full day of engine surveys but these were a few things I immediately noticed. That, and surprisingly how much room you have to move around them in a 420 - the ER hatch is huge!

1) Belt dust - Normal
2) gets really hot there, burns off the paint - Again, normal
 
The exhaust manifold where it attaches to the head - what looks like surface rust on the manifold exhaust passages (not the head). Its about the only place I see rust on the engine, and the boat has never been in salt. Maybe its just the iron surface rusting over time, anyone else see anything like that on their engines?

Here's a picture from my pre-purchase survey. This was 7 years, and over 2000 hours ago. They had 400+ hours on them then, still look the same. The paint probably burns off in the first hour they're run and then stays the same till?
DSC_0018.JPG
 
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