Official Cummins 6cta 450C thread

These engines should run 160-164 if they are clean. Mine run 162 when we have 90* water here in Texas. So you’re probably on the right track cleaning the exchangers but don’t forget the aftercoolers and gear coolers as well.

the exchangers are easily removed and I would take them off and acid clean and pressure test them instead of just rodding them out in place. They do get pin holes and leak.
Just finished having the aftercoolers cleaned and tested. was debating taking off the heat EX vs roding them out. The starboard one looks hard to reach the hoses. Also what would be the best process to drain the antifreeze the hose at the filter?
 
I use the filter hose to drain the starboard engine like you said, and the petcock on the engine oil cooler to drain the port engine.
 
I finished cleaning up my aftercooler cores today. My stbd core is 6 years old and it looks like the PO never serviced it. It took some serious hammering to get it out of the housing. But once out it and the housing were in great shape. No major surprise being 3 of those last 6 years were mostly in fresh to brackish water. I'll lube it up using the Tony Athens method and hopefully itll come apart nicely in 3 years from now.
The port side was the original core and housing from 2004. It was last serviced in 2013 and it came apart easily. Although I did find 10 pieces of old impeller jammed up in the base. Surprisingly I had no cooling issues however I'll be checking the impeller which is supposedly 1 season old (new to me boat). The core looked dirty but not awful. See picts. The cooling fins at the very top and bottom had some corrosion. I think it's fairly normal from what I have read but lmk what you think? The water passages were mostly clear except 2 in the furthest corners which took some force to clear the 1/4" passage. I'll be pressure testing once i come up with a contraption to confirm all is well at 35psi or so.
I did find it interesting that the newer gen core has got to weigh about 10lbs more than the original core. They noticeably beefed up the top and bottom cylinder walls that mate to the housing. The core fins also seem to have a little different design.
Below are some before picts of the old core and after clean picts of both cores. In the top view pict you can see the difference in design. Overall I think the cores cleaned up nice using 5 cans of brake cleaner and soaking in simple green for 5 hours.
 

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This whole weight difference between the newer core from 2014 compared to the original 2004 core had my curiosity going. From everything i had read about the aftercooler changes that occurred in the early 201x's, was that they only changed the housing and added a condensate drain. My understanding was no core changes. Wrong. As mentioned above, the mating surface perimeter at the top and bottom of the core is more substantial, but i thought that couldn't be all of the weight delta. SO i counted the copper cooling plate/fins. The old unit has 356 cooling fins, where as the newer one has 540. A 50% increase in number of fins is pretty substantial. So obviously Cummins recognized multiple deficiencies across the old design. It probably has something to do with the huge price increase on this product that occurred when the new design came out. It now has me contemplating picking up a new core...
 
Interesting. I bought completely new ones when I purchased the boat and I couldn’t get the old ones apart even though I pressed them with a 10T press. I haven’t had cooling issues thus far but the new housings still require some touch up with aluminum black even though I follow Tony’s procedure to a tee.
 
What is the better descaler for the cooling side? Rydlyme or Barnacle buster? After cleaning out my HE this weekend i have a much better idea of how the cooling water flows and how critical it is to keep it clean and serviceable. Definitely have to make sure those pieces of zincs are removed annually. In my case it seems the broken down piece of zincs did a heck of a job blocking some of the tubes.
 
What is the better descaler for the cooling side? Rydlyme or Barnacle buster? After cleaning out my HE this weekend i have a much better idea of how the cooling water flows and how critical it is to keep it clean and serviceable. Definitely have to make sure those pieces of zincs are removed annually. In my case it seems the broken down piece of zincs did a heck of a job blocking some of the tubes.

Did you find a good flexible dowel of some sort to rod out the HE? Or did you end up pulling it off.
I have only seen picts of barnacle buster and it looks like it works wonders on the HE.
 
I rod them out in place. I ended up buying the below rods from amazon. They worked ok on the light obstructions but there were a few that i had to use a brass rod that i picked up form the home depot. The plastic rods got into where i couldn't with the brass ones. Hardest area i will say is front of the starboard end. That is the hardest to see and it had the most amount of old zinc build up. I'm guessing if your temps were spot on the build up in the HE is not bad. I ran about 10-15 degrees warmer and i see why. I would say at least half of my tubes were blocked on both sides. All in all it was tedious but not hard.
https://www.amazon.com/gp/product/B00270WNMO/ref=ppx_pop_dt_b_bia_widget_title_o00_s00?ie=UTF8&psc=1
 
I pressure tested my older core and it held 30 psi with no leaking. The newer core was also fine.
For anyone looking to build a pressure tester you can do it with about $15 in parts at home depot or a hardware store. I purchased a shrader tank valve with 1/8" mip threads. A 1/2" mip to 1/4" fip brass coupler. A 1/4" mip to 1/8" fip brass coupler. Use pipe dope and thread these three pieces together. Then thread it into one of aftercooler zinc holes. Next I purchased two 1-1/2" flexible end caps. These come with hose clamps installed. These are cinched down on the aftercooler end caps to keep the air in. Thread in your second aftercooler zinc to seal the water side off. Then hook up a bike pump and pump her up to 25-30 psi. I let it sit for a couple hours and saw no loss. I had a bicycle shock pump attached to monitor pressure and fine tune the amount of pressure in there.
 
What is the better descaler for the cooling side? Rydlyme or Barnacle buster? After cleaning out my HE this weekend i have a much better idea of how the cooling water flows and how critical it is to keep it clean and serviceable. Definitely have to make sure those pieces of zincs are removed annually. In my case it seems the broken down piece of zincs did a heck of a job blocking some of the tubes.
I try not to use any of it and clean everything by hand, but if I do I use Barnacle Buster. My only regular use of it is on the ac cooling lines. It's safer phosphoric acid based (as Frank mentioned in the other thread). Although, I do drop my zinc plugs into muriatic acid to eat away any zinc stuck in the threads.
 
Now that I have the Aetna digital thats, I don't really have to use the synch gauge so I am considering replacing it with something more useful. My first candidate is a single boost gauge that displays the boost for both engines. It turns out Seaboard Marine has such a gauge with one needle green and one needle red for the dual engine version. Looks like cutout needed is about 2.25 inches. So I have to see if that will fit. Max psi displayed is 30. I assume that is plenty for our engines?

Has anyone installed one of these gauges?

https://www.sbmar.com/product/smx-marine-turbo-boost-gauge-kit/
 
I don’t know that existed. Super cool. I see they have them with EGT too but that would require 2 gauges.
 
I don’t know that existed. Super cool. I see they have them with EGT too but that would require 2 gauges.
Yes, I agree. Pretty cool. This idea just popped in my head this morning. It is a $300 investment if you get all the hardware needed from sbmar. My3Sons will have to be my consultant on where and how to install the sensor at the air intake. He has installed the combo boost/egt gauge. Although it looks like I can install it where the air temp sensor was that I removed when I removed the gird heater stuff.
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That is pretty nice, and a perfect location for the gauge. Yep, the grid heater thermistor port is where I tapped in for the tubing. As far as the 30 PSI question, yes, that's good. If the boost is over that, you"re overloaded. The gauges I have go to 30 psi, I see the new version of those gauges goes to 40. 2300 cruise is around 20 psi. WOT 25ish. It used to be a little more before the last round of prop tuning to get the rpms to 2700 ++ at full travel weight. They're not working as hard now so the boost dropped a few pounds. As far as the length of tubing, I honestly don't remember, been to long. I would guess I ordered somewhere around 80' for both motors, I had some left over. Go for it! I have 2400 hours on mine and you have brand new turbos, we are propped really close so I'd like to see your numbers.

Typical cruise numbers.
DSC_0609.JPG
 
That is pretty nice, and a perfect location for the gauge. Yep, the grid heater thermistor port is where I tapped in for the tubing. As far as the 30 PSI question, yes, that's good. If the boost is over that, you"re overloaded. The gauges I have go to 30 psi, I see the new version of those gauges goes to 40. 2300 cruise is around 20 psi. WOT 25ish. It used to be a little more before the last round of prop tuning to get the rpms to 2700 ++ at full travel weight. They're not working as hard now so the boost dropped a few pounds. As far as the length of tubing, I honestly don't remember, been to long. I would guess I ordered somewhere around 80' for both motors, I had some left over. Go for it! I have 2400 hours on mine and you have brand new turbos, we are propped really close so I'd like to see your numbers.

Typical cruise numbers.
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Mark do you know if I need to buy their $75 sensor adapter? That would be one for each engine. So $150 for a couple of reducers seems outrageous. I guess I'll give sbmar a call when they open.
 
I don't really know what a sensor adaptor is. The fitting that came from them for the tubing was an 1/8 tubing push lock x 1/8 mpt. I just bought a bushing for the thermistor port.
 
I don't really know what a sensor adaptor is. The fitting that came from them for the tubing was an 1/8 tubing push lock x 1/8 mpt. I just bought a bushing for the thermistor port.
Looks like it's just 1/8 female to 1/2 inch male adapter (or whatever thread size the hole on the engine is). What exactly did you use? A brass version of the same thing online is about $5. That's one crazy markup. Also did you buy their long tubing or buy it elsewhere?

https://www.sbmar.com/product/cummins-marine-6cta-8-3-boost-adapter-fitting/
 
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The adaptor shown in your link above is for a plug in the intake manifold that is not pipe thread. It's a straight thread with a gasket for the plug. When we put the boost gauges in my friends boat, He just drilled and tapped the plug that goes in that location to 1/8 npt. His earlier version diesel did not have any other port available for the boost tubing. Don't buy that.
I just bought a brass bushing at the hardware store for the thermistor port, 1/2"? x 1/8. the thermistor port is pipe thread.
then threaded their 1/8 push lock x 1/8 mnpt fitting in that. The push lock came with the "kit". I bought more tubing locally. I don't have a picture of the install on this laptop I have here in FL, sorry.
 
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Bill, found a picture. Go back to post #298 here. Looks like I just bought 2 brass bushings to make it from 1/8 to 1/2. I couldn't remember.
 
Has anyone had to replace an oil pressure sending unit on one of our 6CTA’s? I am trying to find a part number or replacement for mine. Seaboard does not have them as there sending units are 2 wire units for VDO type gauge, for some reason the s
Sea Ray 4 in 1 gauge are different, these use a single wire, basically looks like your run of the mill old school oil pressure sending unit with a single stud. I just want to make sure I am ordering the correct part. Haven’t tried Marin Max yet but maybe they have one??
 

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