Official Cummins 6cta 450C thread

Has anyone adjusted their fuel aneroid? Since I've owned it, one of my engines has had a slight delay (a few seconds) spooling up the turbo and after eliminating everything else (air restriction, exhaust leak, etc) I'd like to see if adjusting the aneroid will make a difference. Here is a link to pictures of it: http://www.sbmar.com/articles/aneroid-adjustment-on-the-bosch-p7100-injection-pump/
I had a lazy aneroid too, and it's an easy job. T20 (I think) with a hollow point to remove the safety end cap. 2 clicks or so is all you'll need to move the wheel.
 
I had a lazy aneroid too, and it's an easy job. T20 (I think) with a hollow point to remove the safety end cap. 2 clicks or so is all you'll need to move the wheel.

Thanks Paul. How long was your delay before you made the adjustment?
 
Before adjustment it was progressively getting worse. I always noticed a 2-3 second lag.....then it went to 7-10 seconds....then I was not able to get over the hump.

Are you getting any black smoke from the lagging engine?
 
Before adjustment it was progressively getting worse. I always noticed a 2-3 second lag.....then it went to 7-10 seconds....then I was not able to get over the hump.

Are you getting any black smoke from the lagging engine?

Nope, no black smoke during cruising. But I've never turned my head to look while accelerating. I'll check that out.
 
Alex,


With the 23x27 and a light load I would hit the governor speed of 2680 on the stbd. And could get to 2650 on the port. The fuel flows at various rpm's were well above the Cummins curve. Tony at Sbmar suggested removing 2 inches of pitch. He also recommended following the fuel curve of the 450C. After removing the two inches both engines easily hit the governor speed with a fully loaded boat. I was, however, below the curve for the 450C. Rather than continue with the Hytorq's I talked to my prop guy and Acme. They suggested 24x26 for my boat. They came with .045 cup. They also have an increased blade area. Now with a loaded boat I just hit the governor with both engines. I am very close to the 450C fuel flow numbers and picked up 2 knots of cruise at 2200rpm. The folks at Acme told me that .030 of cup equals 45 rpm.


Hope this helps

I had a failure on my 480ce engine, melted #6 piston. Tony at boat diesel was a great help, he said I was way over propped. He recommended that I re-prop my boat, which I did. I am running 25.5 pitch down from 27. The motors fuel curve is right at the 450 stat. According Tony the 480ce is the same motor as the 450 inside. Therefore the load should be propped to it. I am now running my 480ce at the 450 levels, the motor seems to be happier. You can not under prop this motor as the electronic governor will kick in and prevent it from over revving. I lost about 3mph on top end.....no big deal as I rarely run more than 2200@26 mph. Fuel economy is better too!
 
I am buying a spare mag switch for the starter just to have in the spare parts bin. In the process I really studied the wiring to it. I got stumped by one of the big power wires. One lug has the power coming in from the battery The other lug has the power going out to the starter solenoid. But there is a second mystery wire on that lug. The label on it has degraded over the years. Where does this second power wire go to?


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I am buying a spare mag switch for the starter just to have in the spare parts bin. In the process I really studied the wiring to it. I got stumped by one of the big power wires. One lug has the power coming in from the battery The other lug has the power going out to the starter solenoid. But there is a second mystery wire on that lug. The label on it has degraded over the years. Where does this second power wire go to?


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That is the "pull" to activate, or latch the fuel selenoid. I think the fuel has both a pull and hold circuit, where the hold keeps the valve open with ignition from the helm.
 
That is the "pull" to activate, or latch the fuel selenoid. I think the fuel has both a pull and hold circuit, where the hold keeps the valve open with ignition from the helm.

Thanks Paul. That makes sense. Sea Ray didn't include the mag switch or any of its wiring in the 12v diagrams. Or at least I couldn't find it. They did show the fuel solenoid. I'll try tracing its wire(s) on the diagram again to see if the mag switch is buried in another diagram.


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Thanks Paul. That makes sense. Sea Ray didn't include the mag switch or any of its wiring in the 12v diagrams. Or at least I couldn't find it. They did show the fuel solenoid. I'll try tracing its wire(s) on the diagram again to see if the mag switch is buried in another diagram.


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Funny, I replaced a starter, and had a similar interest in the wiring....sbmar published good diagrams.

http://www.sbmar.com/articles/6bta-5-9-6cta-8-3-mechanical-engine-wiring-diagrams/
http://www.sbmar.com/articles/basic-fuel-shutoff-solenoid-starter-wiring-information/
 
I am helping a new owner do all the deferred maintenance on a 15 year old pair of 6cta. Found out we need two new aftercoolers. Thought I'd pass on that the price recently pretty much doubled from $1700ish each to $3000+. Also they now have two drain holes on the air side but don't come with the drain kit to screw in. You have to know to buy them separately.


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Doing aftercoolers right now. Bottom and top of my port aftercooler after 2.5 years in salt year round. Update: Air side had some condensation corrosion. Will stick with a two year cycle.
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Last edited:
Well, the 15 year old aftercooler was bad (I had replaced the other one 3 years ago). So I had the pleasure of buying a new one for roughly the price of a good used 18 ft runabout. Cummins doubled the price a few months ago. It's clearly a poor design with three metals with the most noble being the aluminum case. I am hoping sbmar comes out with a custom replacement one day.


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While the aftercoolers are off I removed the grid heater circuitry. They are fried and didn't work and I don't really need them down here. I thought I'd post this in case anyone else wants to do this. Process was straight forward. Remove the two power and one ground wires and temp sensor connector at the grid block. Disconnect the three control connections - one for power control, one for preheat and one from rpm pickup. Remove the main power cable from the starter lug. Remove the two bolts holding the bracket on. That's it. Lots of room there now.
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I made up a maintenance schedule with part numbers and sources. I'll be glad to send it to you if you pm me your email. Sorry but it includes a Westerbeke generator rather than an Onan.

Hi Bill-

New owner of a 460DA with 450 cummins- do you mind sending me that maintenance schedule as well? Thanks!
 
Hi Bill-

New owner of a 460DA with 450 cummins- do you mind sending me that maintenance schedule as well? Thanks!

Sure will. Just PM me your email address.


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Just coming into my third season. Had some major work done this winter.. after coolers, exchangers, belts, heater solenoid , and idler pulley . Good news on all - modest cleaning etc. nothing scary
boat is newer to me without good records. With that wanted to get on schedule -1100 hours

Installed by me :
upgraded sea strainers with groco safety - water flush valves .
new raymarine es127 , engine room camera and quantum radar

(2) issues last summer
1. Loss of power. Was running 2100-2200 rpm @ 21-22 kts. Mid summer same rpm but it's down to 18 Growth was moderate as best ... could that have been the issues .?

2. Trans coupler (strbd). She went. Not fun as I was seven hours out and ran back on the port. What are the chances that the port side goes..

I appreciate any comments as I come from the gas I/o world.
 
Moderate growth especially on the running gear will cause the speed loss. More so if the boat sits idle for a few weeks between uses.

As far as the coupler goes they rarely fail but I am one of those types that always repair/replace on both sides at the same time.
 
Just coming into my third season. Had some major work done this winter.. after coolers, exchangers, belts, heater solenoid , and idler pulley . Good news on all - modest cleaning etc. nothing scary
boat is newer to me without good records. With that wanted to get on schedule -1100 hours

Installed by me :
upgraded sea strainers with groco safety - water flush valves .
new raymarine es127 , engine room camera and quantum radar

(2) issues last summer
1. Loss of power. Was running 2100-2200 rpm @ 21-22 kts. Mid summer same rpm but it's down to 18 Growth was moderate as best ... could that have been the issues .?

2. Trans coupler (strbd). She went. Not fun as I was seven hours out and ran back on the port. What are the chances that the port side goes..

I appreciate any comments as I come from the gas I/o world.


I keep my boat at a large Sea Ray servicing dealer's marina on the Gulf Coast. We have had couplers fail on several 2003-2008 Cummins "C" powered boats and the marina always changes both at the same time when they repair one. The good news is that once they are replaced, they never fail again.

I would do both and get it over with.............
 
While we're on the subject of transmission gear coolers, my boat is too far from me. Does anyone know the dimensions of our gear coolers? Is it 14" overall length, 1/2"NPT gear and 1-3/4" water hoses?

BTW, I totally agree with Frank. The life expectancy for the coolers around 10yrs. If one went, it's only a matter of a short time frame for the other one go. I would replace both at the same time or at least schedule the other side to be done soon after.
 
I just happen to be doing a little work in the er today, and those dimensions look correct.
 

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