Official Cummins 6cta 450C thread

Thank you for your comments. Actually there were some circumstances including the owner is a friend of a friend, very good price, and the engines seem very clean (600 hours), that made me buy it without the full inspection (without hauling it out). I got a favorable dockside and engines inspection though. Skipper now admits that he did not push the throttle to the max at sea trial!!

Will do another test when the weather permits and check everything else and post the results here. Thank you for your help.

There was virtually no smoke during the trials.

If we disassemble the aftercoolers, what are the signs that the core needs replacing instead of just cleaning?
If it's really bad, you won't be able to get the core to slide out. If it does slide out then look for lots of pitting and metal loss at and about the ends of the aluminum case. Also look for white stuff caked on the cooling fins of the core. If you think it's still useable, after you clean it up and put it all back together, have it pressure tested. Sbmar.com has a nice tutorial on the process.
 
Seacruiser

Welcome to the group! To each his own but buying a boat without a survey is very risky and you will most likely need it to obtain insurance anyway but that is your choice. The 600 hours on an 18 year old boat is also a concern. It’s not the same as gas engines, diesels like to be ran and I’m guessing you will have significant deferred maintaince items to address.

The answer to your aftercooler question is simple. The cores are copper and the housings are aluminum so typically the dissimilar metals corrode and you cannot get them apart. Make sure to take time and look at the posts on sbmar.com as Tony is the expert on these engines and everything you will ever need is on his site.

I am a Cummins fan and have serviced almost everything possible. With an engine this old you will need to to service/inspect:

Aftercoolers
All hoses
Heat exchangers
Turbos
Belt
Belt tensioner
Alternator
Coolant (specific method and filters)
Oil
Transmission coolers
Valave adjustment
Airsep housing and filters
Zincs
Raw water pumps

I’m guessing again but you probably have a westerbeke generator that needs some loving as well.

Bill, myself, and others are all doers so feel free to ask anything necessary or pm me and we can talk via phone.

The WOT thing is a necessary evil so get her clean and go for a test run and report back on that.

Good luck and welcome to the club!

Josh
 
Thank you Josh, I will check all items on the list and will report back WOT RPM as soon as we can have it cleaned.

Bill, thank you for the pointers about the aftercoolers.
 
Hi. Changing subject.. I noticed lately that warm oil pressure at idle show 20 PSI. At acceleration it goes up to 50 PSI. Checked both at pedistal and the live line on the engine. Seems to me a bit low (20 PSI).
Any ideas?
(Cummins c6 450)
 
Hi. Changing subject.. I noticed lately that warm oil pressure at idle show 20 PSI. At acceleration it goes up to 50 PSI. Checked both at pedistal and the live line on the engine. Seems to me a bit low (20 PSI).
Any ideas?
(Cummins c6 450)
Totally normal.
 
Stopped by the boat today after taking my daughter to the airport. First time back since early November. It sure felt good stepping off of the dock onto the swim platform!

I lifted the engine hatch and dropped in to just check things over. I remembered something that we found last fall when we did the aftercooler/gear oil cooler/heat exchanger work. On the Port Engine, just behind the aftercooler, way down low, we notice some corrorsion on an electrical connection. See picture.

What is that for? My guess is the grid heaters.

Thanks,

Jaybeaux

PS....Any special precautions needed when cleaning? Just don't touch wire brush across to anything else?

20190107_120642.jpg
 
1. Shut off power. 2. Soak with PB blaster and remove cables for cleaning. 3. Wire brush and sandpaper to clean terminals to bare metal. 4. Reinstall and spray with corrosion block or coat with dialectric grease to prevent recurrence.
 
Did my every two year heat exchanger cleaning. Only I stretched it to 3 years this time. Cooling tubes were all clear except for some zinc residue caking at the bottom. I dissolved it away with some eye dropper applications of muriatic acid. But the end cap gaskets were turning to a gooey mush. Put four new gaskets and o rings on.
 

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Bill, did you add any sensors to your engines, EGT, boost, fuel flow etc.. It would be nice to see some photos of the senders. I am thinking of adding a temp sensor in the exhaust pipe after water is mixed, I think it will be the best early indication of lack of fresh water. I am getting these https://www.ebay.com/itm/Marine-Exh...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649 Supplier said to drill a 4mm hole in the exhaust tube for the sensor, anyone did that? Is it ok to do?
 
Bill, did you add any sensors to your engines, EGT, boost, fuel flow etc.. It would be nice to see some photos of the senders. I am thinking of adding a temp sensor in the exhaust pipe after water is mixed, I think it will be the best early indication of lack of fresh water. I am getting these https://www.ebay.com/itm/Marine-Exhaust-Temperature-Alarm-Gauge-Monitor-Sensor-SM012/153278185597?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649 Supplier said to drill a 4mm hole in the exhaust tube for the sensor, anyone did that? Is it ok to do?
I did not but My3sons (Mark) did. He's a skilled diesel expert and did a great job. Hopefully he will respond here. He did not drill any new holes. He used existing ports on the engine.
 
Thank you for the fast reply. About cleaning the heat exchangers, I am worried that if I open it, it will mix seawater with coolant, or spill the coolant, or ... Because I am not sure how it is made inside. I did open the aftercooler and removed the core for cleaning, no risk there. So, about the H/X, you open the side, do you remove the core? Does it spill the coolant?
 
Thank you for the fast reply. About cleaning the heat exchangers, I am worried that if I open it, it will mix seawater with coolant, or spill the coolant, or ... Because I am not sure how it is made inside. I did open the aftercooler and removed the core for cleaning, no risk there. So, about the H/X, you open the side, do you remove the core? Does it spill the coolant?
The core on the HX is bonded to the casing. So there is no core to remove. You can take the end caps off to inspect the sea water cooling tubes. Nothing will spill out. It's a 14mm bolt head. What I did when I bought the boat was drain the coolant and remove the heat exchangers and take them to a radiator shop to have them cleaned and pressure tested. That checks for leaks between the salt water side and the coolant side. I did this since I did not know their maintenance history. Now I take the end caps off every two years and clean out anything stuck in the tubes. Not sure when I will pressure test again.
 
Ah.. that made it clear thank you Bill. So there is one gasket and one o-ring on each side?
About pressure testing, I am thinking of making a special hose fitting with air pressure gauge to test the whole seawater side pressure in one shot. Would disconnect the water pump output (to insert a fitting with air pressure. max 30psi) and disconnect the wet exhaust input (to connect the fitting with gauge) and do the test... will have to block the hose to the dripless shaft seals. In case of leaks, listen or drip some water on hose connections to see if/where it bubbles. Bad idea?
 
I did not but My3sons (Mark) did. He's a skilled diesel expert and did a great job. Hopefully he will respond here. He did not drill any new holes. He used existing ports on the engine.

Ha! You neglected to preface that by saying “old school retired”.
And I would always feel a little more old school each time I would watch one of my new kids plug his computer into the new tier motors to run a diagnostic. Ah but change is good, when I was home at Christmas the guys at the shop said they are having hardly no problems at all with the newer power plants, and they are actually starting to have less down time, about par with the old stuff.
 
I read that "old school required" because that's what I am looking for now.
 
SeaCruiser, here are some pictures. I have not installed flow meters.

63161BED-322A-43F9-A478-B0F2D3437FC4.jpeg

Above you can see the egt sensor, there is a 1/8 pipe plug in the mixer elbow for the install. Last year I completely rehosed the engines and at that time added Borel exhaust temperature alarms. They simply strap onto the exhaust hose right behind the shower outlet, that way if the water stops flowing, that hose gets instantly hot in that spot. You can see the black strap and the purple and black wire pigtail from the borel. Aqua alarm also makes a similar set up.
I did not install the alarm panel at the dash as I just wired them into overheat temperature switches that I had installed previously on the coolant side of the system, which you will see next.

641B987E-B86F-4536-9647-94ACD25E0193.jpeg

I the picture above you can see the overheat switch in the exhaust manifold. It is simply a normally open 200 degree single wire switch that you can get from napa. If there is a fail in the coolant side of the system, the exhaust manifolds are the first to get hot, much sooner than the standard temp sensor that is located half way down the engine block. There is a 1/2” pipe plug in the manifold where I installed it. I have a horn and a light at the dash for both the switch and the Borel alarm, one for each engine.
At the bottom of the picture, in the air intake elbow next to the intake heater box is the connection for the turbo boost gauge. That is the port where the thermistor for the air intake heaters was located. I removed my intake heaters after one of them malfunctioned and almost started a fire. I was looping at the time and was 1000 miles from home. After completing another 7000 miles with one intake heater and seeing absolutely no difference in how the engines behaved, I took out the other one too. There are other spots in the intake manifold that you can tap into for your boost line.

88914733-D987-4D1F-93AA-B4BE26364F7B.jpeg

I used Ispro combination gauges for the egt and boost. I mounted them to the left of my auto pilot control. There may be other places at your helm that you may prefer.
Hoped this helped a little. Have fun
 
Thank you Mark for the excellent information and for the welcome. I am happy to be here. Will try to do a very similar setup as yours.
 

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