Official Cummins 6cta 450C thread

my3sons said:
OK, I must have misread your posts and photos. I thought the temps in the 150’s were underway and from the sensor you put in the exhaust manifold. The exhaust manifold is the hottest coolant, it goes from there to the tstats. 150‘s wouldn’t even open them to send the coolant to the hx
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Post #1456 was underway and yes the readings were in the 150's. My earlier post #1446 was at the dock. I did test the sensors in hot water prior to installing so I do think they are very accurate. However I've been trying to understand this flow chart from the seaboard site as I agree that the manifold coolant should be the hottest as it seems to be the last stop before the tstats. What I did observe is that it would get to 158 then it would drop down to 152. My assumption is that while running the tstats are mostly "somewhat" open because of the time it takes them to open and close. I think, and correct me if I'm wrong, the analog temp sensor is down in the area below the tstat housing near the alternator which seems to have the hotter coolant.

www.sbmar.com

Cummins Mechanical B & C Coolant and Raw Water Flow Diagrams

www.sbmar.com www.sbmar.com
 
Irie308 said:
Post #1456 was underway and yes the readings were in the 150's. My earlier post #1446 was at the dock. I did test the sensors in hot water prior to installing so I do think they are very accurate. However I've been trying to understand this flow chart from the seaboard site as I agree that the manifold coolant should be the hottest as it seems to be the last stop before the tstats. What I did observe is that it would get to 158 then it would drop down to 152. My assumption is that while running the tstats are mostly "somewhat" open because of the time it takes them to open and close. I think, and correct me if I'm wrong, the analog temp sensor is down in the area below the tstat housing near the alternator which seems to have the hotter coolant.

www.sbmar.com

Cummins Mechanical B & C Coolant and Raw Water Flow Diagrams

www.sbmar.com www.sbmar.com
Click to expand...
I’ll pick on you all a little bit. Why such concern for redundancy in temp sending? Clean your aftercoolers every two years and rod out your heat exchanger and gear oil cooler at the same time and you’ll always run cool as a cucumber unless you snap a belt or neglect the impellers.
 
ZZ13 said:
I’ll pick on you all a little bit. Why such concern for redundancy in temp sending? Clean your aftercoolers every two years and rod out your heat exchanger and gear oil cooler at the same time and you’ll always run cool as a cucumber unless you snap a belt or neglect the impellers.
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I hear you but why not. It was little effort to add them and I was bored...hahaha. You forgot to include broken thermostats. Honestly I never trusted my analog gauges but after changing my coolant and thermostats they are spot on so now a little redundancy doesn't hurt.
 
scooper321 said:
So the sensor threads right into that plug? That's really interesting. All of the temperature mods I've heard about involved drilling holes and tapping threads, and I am not brave enough to do that in my engine anywhere. I know there is a port near the exhaust that can also access a sensor, provided it is accessible past the exhaust flange. Is that where you are getting your exhaust reading?

It makes sense that the coolant temp would be lower than the exhaust temp. But I am also surprised by the large difference, too. The coolant temperature makes sense to me, however. These engines run around 170°, so I would expect the coolant to be lower than that in order to keep it at that temperature. The exhaust temperature reading is an eye-opener for me, but I have no reference for what they should be. Next time I'm cruising I will shoot mine with my temp gun.
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The plug is a 1/2 npt fitting and I had to reduce it down to take the 1/4 npt sensor. if you read up on Seaboards documentation of this motor there are all sorts of ports that are plugged off and not used in our application. So far i've added sensors for boost, EGT, coolant temp, transmission temp and pressure. All of which are via threaded ports that are plugged up from the factory. For me boost is the eye opener. As i said my gauges are wonky sometimes. If i feel i'm lugging or something is not right I first check my boost. Same for EGT's.
 
ZZ13 said:
I’ll pick on you all a little bit. Why such concern for redundancy in temp sending? Clean your aftercoolers every two years and rod out your heat exchanger and gear oil cooler at the same time and you’ll always run cool as a cucumber unless you snap a belt or neglect the impellers.
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You are correct. You could also add a burst hose, suck a bag up against the water intake, etc. For me it’s not about the temperature reading, it’s about one of those unexpected events. If the coolant stops flowing or stops being cooled, that location will get hot first. I put an alarm switch in that plug hole hooked to an alarm and a light on the dash.
I was just wondering about his coolant temperature reading. Seems too low to me. If I shoot the expansion tank, not part of the motor at all, it’s almost 170 degrees. It’s safe to say the tank doesn’t heat the coolant above what the temperature is in the motor. No way I would think that the coolant running through the hottest part of the motor is in the mid 150’s, especially since the t stats don’t even start to open until 160.
 
Irie308 said:
Post #1456 was underway and yes the readings were in the 150's. My earlier post #1446 was at the dock. I did test the sensors in hot water prior to installing so I do think they are very accurate. However I've been trying to understand this flow chart from the seaboard site as I agree that the manifold coolant should be the hottest as it seems to be the last stop before the tstats. What I did observe is that it would get to 158 then it would drop down to 152. My assumption is that while running the tstats are mostly "somewhat" open because of the time it takes them to open and close. I think, and correct me if I'm wrong, the analog temp sensor is down in the area below the tstat housing near the alternator which seems to have the hotter coolant.

www.sbmar.com

Cummins Mechanical B & C Coolant and Raw Water Flow Diagrams

www.sbmar.com www.sbmar.com
Click to expand...
I have always believed the coolant flow to be roughly from the circulation pump to:
the engine oil cooler, the head and block, through the turbo housing, the exhaust manifold, to the Tstat housing. If the tstats are closed, it bypasses the hx and goes back to the circ pump, if the t stats are open, it flows through the hx Back to the circ pump.
 
I need some help. I changed my Racor filters (with new O-rings) and the prime pump on my 480CE (same as the 6CTA). The issue I'm facing is that the engine seems to be continuing to lose prime and won't start. Is there something I'm missing or something else I should be doing?
 
From your description, I'd look towards the Racors. Likely pinched an o-ring or it fell out of place.
 
We are in the process of buying a 2005 460 Sundancer with 450c engines. Got the oil sample back and one engine showed an abnormal amount of potassium. Number was 121 to be exact. Coolant was also low. Cummins tech was doing the 1000 hour service yesterday when samples were drawn. He said it could be an oil cooler or maybe an exhaust manifold.....maybe even the overflow cap. He thinks it will be OK if we keep an eye on it and make sure the coolant inst low before using it. Do you think this should be a bigger concern? Any help is appreciated.

Also, the transmissions came back with high metal content but he said it was do for a fluid change and they should be fine. This is a fresh water boat and has been on the same lake its entire life.
 
Timmyg said:
We are in the process of buying a 2005 460 Sundancer with 450c engines. Got the oil sample back and one engine showed an abnormal amount of potassium. Number was 121 to be exact. Coolant was also low. Cummins tech was doing the 1000 hour service yesterday when samples were drawn. He said it could be an oil cooler or maybe an exhaust manifold.....maybe even the overflow cap. He thinks it will be OK if we keep an eye on it and make sure the coolant inst low before using it. Do you think this should be a bigger concern? Any help is appreciated.

Also, the transmissions came back with high metal content but he said it was do for a fluid change and they should be fine. This is a fresh water boat and has been on the same lake its entire life.
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I would assume that these are analysis as a part of the survey for purchase?
1000 hour service - what is that?? For QSB, QSC, and QSM - There is annual anode change, 500 hour or annual oil and other routine then 2000 hour cooling system and 5000 hour overhead set. However, annual is way less than 500 hours in my case.
You didn't state how many hours are on the oil that was sampled which is important in understanding the results.
Regardless on the potassium, you have to look at the other elements to understand better how potassium got there. A couple of drops of coolant in the oil during oil change would do that FYI. I would agree though that this would be something to monitor on subsequent oil analysis and changes.
The gear is more concerning, however, you don't say what metals.... Copper would indicate a potential cooler issue or excessive clutch wear, chromium would indicate bearing wear, aluminum would indicate a potential issue with the case or valving, iron would be gear wear or clutch wear. What is important is to analyze the elements holistically in order to determine the most probably cause and if it is a concern or not. If you post the analysis here there are a lot of knowledgeable folks that could help you.
For me, I do analysis on all of the oils every year/oil change. It is the trends I pay attention to.
 
Re the Racors, did you turn the fuel valves off to change the filters? Did you turn them back on afterwards? Don't ask me how i know......
 
Timmyg said:
We are in the process of buying a 2005 460 Sundancer with 450c engines. Got the oil sample back and one engine showed an abnormal amount of potassium. Number was 121 to be exact. Coolant was also low. Cummins tech was doing the 1000 hour service yesterday when samples were drawn. He said it could be an oil cooler or maybe an exhaust manifold.....maybe even the overflow cap. He thinks it will be OK if we keep an eye on it and make sure the coolant inst low before using it. Do you think this should be a bigger concern? Any help is appreciated.

Also, the transmissions came back with high metal content but he said it was do for a fluid change and they should be fine. This is a fresh water boat and has been on the same lake its entire life.
Click to expand...

I'm surprised you have the 450C in a 2005 boat. Would have expected you to have the 480CE.
 
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Timmyg said:
We are in the process of buying a 2005 460 Sundancer with 450c engines. Got the oil sample back and one engine showed an abnormal amount of potassium. Number was 121 to be exact. Coolant was also low. Cummins tech was doing the 1000 hour service yesterday when samples were drawn. He said it could be an oil cooler or maybe an exhaust manifold.....maybe even the overflow cap. He thinks it will be OK if we keep an eye on it and make sure the coolant inst low before using it. Do you think this should be a bigger concern? Any help is appreciated.

Also, the transmissions came back with high metal content but he said it was do for a fluid change and they should be fine. This is a fresh water boat and has been on the same lake its entire life.
Click to expand...

fr8dog said:
I'm surprised you have the 450C in a 2005 boat. Would have expected you to have the 480CE.
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engines are 6cta8.3-m I was using what he labeled them on the oil samples......and this is our first time having a boat with dieseles so we dont know much.
 
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