Official Cummins 6cta 450C thread

All cleaned up and ready for reinstall....awaiting SBMarine parts shipment. Is it worth pressure testing the tubing bundle before install and if so what pressure?
 
Test for sure. One of yours looks a little discolored at the bottom. This is from a QSC but same principle. This has 525 hours on it but is 13 years old and removed for service only one other time since new! Saltwater since new and never flushed but acid cleaned numerous times which I think caused the leak where the tubes are inserted in the housing.
I tested at 30 pounds, should hold over night.
 

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Just changed the coolant in my 2004 6CTAs tonight. Relatively easy job, especially if you have a couple of extra hands onboard. As always, one engine easier than the other. My Starboard was a piece of cake. The Port was a bit of a bitch in that the petcock on the block is outboard, under the exhaust tube. A bit of coolant in the bilge means bilge cleaning tomorrow. Will run the engines a bit to work the air pocks out. I have right at 7 gallons of new 50/50 EC coolant in them now. New filters arrive tomorrow (blanks) and then a touch in the expansion tanks. Thanks @ZZ13 for the tips! As usual spot on!

Jaybeaux
 
at first glance, how concerned would you be with this aftercooler tanning on a motor with ~800 hours? They're in a 2003 460DA. I'm just window shopping but this isn't the first time I've come across one that looks like this so figured it's worth the ask
upload_2020-6-21_21-17-22.png
 
I wouldn’t be too concerned.... it looks like it’s a little hot but depends on the last time it was painted.... if never I wouldn’t be worried.... this is the best pic I have of mine ....you can see a bit of yellow ....always ran at 2150/2250


32A15251-6678-4E31-839E-1CCFAD1AB50D.jpeg
 
Darker then normal. Possibly overpropped (since it's a Sea Ray more like probably) and owner likes to go fast all the time. Not a deal breaker for me at 800 hours but fully loaded WOT test is in order as soon as possible and then probably prop pitch reduction

Some good discussion on this topic here:

https://www.sbmar.com/community/topic/6cta-discoloration-on-turbo-pipe-and-cooler-cause/
Bill, my port engine idles rough, and have to move the throttle up to sync with starboard, is there anything you can recall in this forum that addresses that?
 
Bill, my port engine idles rough, and have to move the throttle up to sync with starboard, is there anything you can recall in this forum that addresses that?
Not to speak for Bill, but I have that same issue. I chalk it up to old, streched throttle cables in need of a bit of adjustment. Curious as to what others say.

Jaybeaux
 
Bill, my port engine idles rough, and have to move the throttle up to sync with starboard, is there anything you can recall in this forum that addresses that?
It's pretty easy to adjust the idle rpm. What's both your starboard and port idle rpm? Over the years I've settled on 625-650 to smooth everything out. But it does increase a bit as the engine warms up. I adjusted the idle when warm. Then when I start it cold it's often too low and I use the throttle to get it back to 625 until it's warm.

since you have straight drives the port idle screw is on the outside of the engine. Hard to access. My guess is no one ever adjusted it because of that. I think I posted my formula to accessing it somewhere here. But if you remove the air pipe between the aftercooler and the engine you can access it fairly comfortable. It means I am removing and connecting that pipe until the idle is where I want it. It's not bad. I don't use the clamps when I do that. I just slip the pipe in and out of the hose pieces.
 
It's pretty easy to adjust the idle rpm. What's both your starboard and port idle rpm? Over the years I've settled on 625-650 to smooth everything out. But it does increase a bit as the engine warms up. I adjusted the idle when warm. Then when I start it cold it's often too low and I use the throttle to get it back to 625 until it's warm.

since you have straight drives the port idle screw is on the outside of the engine. Hard to access. My guess is no one ever adjusted it because of that. I think I posted my formula to accessing it somewhere here. But if you remove the air pipe between the aftercooler and the engine you can access it fairly comfortable. It means I am removing and connecting that pipe until the idle is where I want it. It's not bad. I don't use the clamps when I do that. I just slip the pipe in and out of the hose pieces.

Thank you Bill, that makes a lot of sense. It’s just the Port of course.
 
On running rough.....

I fueled up and ran for about 5 hrs steady on plane. Near the end I started to think something sounded different, possibly an almost un-noticeable vibration. I have to run trawler speed for almost an hour coming down the canal so experimented a little trying to see if it was one engine or both. The stbd side seemed to be running the worst.

I pulled the filters this this weekend, the stbd side was loaded up with crap real bad. The portside was bad but not quite as much. When I had fueled up we put a 100gal in stbd side first and then filled the port side. I treat my fuel every fill and have never had any problems even with the long winter layups. I believe I got some bad fuel, going to call that marina this morning.

Anyway, after the filters were changed took the boat out, all running smooth again. Looks like I'll be doing some extra filter changes this summer until the fuel is cleaned up.
 
Add a biocide in shock treatment quantity. I use biokleen
 
Looking for some help. My port engine hour meter stopped working on my tach today. Everything else on the tach works fine. Is there somewhere on the motor it’s getting its signal from? 2003 mechanical version. Thanks
 
Looking for some help. My port engine hour meter stopped working on my tach today. Everything else on the tach works fine. Is there somewhere on the motor it’s getting its signal from? 2003 mechanical version. Thanks
The tach inputs power, ground, the rpm pickup signal and a backlighting signal. If you are getting an rpm reading then the problem is all inside the tach.
 
Both out....so put them on three 4x4 blocks and used a hand jack against an unmovable object. The second one was a little more difficult to get moving. Under load, I tapped the housing with a hammer and if was free. I ended up having to move the core in and out a few times and clean each side before it would slide out. The professionals use a aluminum puck the same size as the core for a push plate. I used an aluminum plate that I had to use as a push plate. Pic is the uncleaned cores as removed with my push plateView attachment 86288
Ended up replacing one tubing bundle due to small leak. Leak down took about 3 hours from 12psi to 0. This was the tube bundle that needed a lot more force to remove so probably what caused the leak. All painted up and ready for install. The new tubing bundle was a tight fit and had to be tapped in place. The original unit slide right in with no force.
 
The tach inputs power, ground, the rpm pickup signal and a backlighting signal. If you are getting an rpm reading then the problem is all inside the tach.
Your saying I'll have to probably replace the tach and that meter will start at zero then?
 

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