Official Cummins 6cta 450C thread

Great timing. I've finally got the boat outfitted and cleaned and weather has been prohibiting taking her out. But I have some spare props (recently tuned by the prev owner) that are 22" x 24. They aren't on the boat now, but I'm told what's on there are also recently tuned 22" x 24 props. It ran to 2500rpm WOT on sea trial, so re-propping is high on my list. Your post is the timely kick in the pants I need to take my props over to the shop and get that 1" of pitch removed and then swap them with what's on the boat (and repeat).

 

Scooper, don’t be convinced that 1” is what you need to do.
Load your boat up like you will normally use it, fill your tanks, and record your results with a laser tach. Then go to a reputable prop shop and tell him what you are turning and what you want to turn, engine model and transmission ratio. Don’t be surprised if he tells you a little more than you expected.
It’s better to do it the first time than to find out it wasn’t enough. Good luck.

 

Damnit. I was looking for the quick and easy way to get it done. Perhaps I'll hold off until our next trip out before dropping any dough. Thx

Steve

 

My starboard side aftercooler is no good. Anyone replaced theirs if so where did you purchase them from
John

 

https://www.sbmar.com/product-category/engine-components/aftercoolers/

 

Where is the best parts houses for Cummins on the east coast...? Located in NJ so hoping to find good stocking distributor with 2-3 days ship time.
Thanks,
Ed

 

Ed

I’d say check diesel parts direct for online sales but to be honest most of the Cummins parts are easy to locate once you look up your part numbers on quickserve. I don’t buy from a single source simply because it depends on price, availability, ship times...etc.

Are you needing something specific and do you have your part numbers?

On a side note: I replaced my tensioners and idler pulleys this past week and did Tony Athens upgrade with the grade 8 bolt. It was an easy upgrade and literally took less than an hour.

I had an issue last year where my port engine would just barely white smoke, it wasn’t a big deal but it really bothered me because I am so picky and want a perfect boat. I had the fuel pump rebuilt and it didn’t change anything so I decided to look into injectors. Come to find out there are 4 different model numbers for injectors so I started reading and learned the final version in the most recent CPL changes from a 4 nozzle spray pattern to a 5. Long story short I didn’t expect much but changed the injectors.

Wow! Was I wrong. My engine puuuuurrrrss. It so smooth my wife thought I only had the generator running. White smoke is gone and needless to say I’m going to change the other engine as well.

Food for thought.

 

I'm looking for raw water piping but can't find in quickserve. Called cummins too and they could not find it. Pipe that runs from the trans cooler to engine heat exchanger.

 

Good afternoon sports fans. What a great weekend for boating here in the Washington DC area. I had a crew of 10 out on the water for 6+ hours. What a treat.

Except.....after 3-4 hours of idling and cruising, it was time to head home. We cleared a no wake zone and throttled up to 2200 rpm for our trip home. Everyone was tired from a long day, so the crew was just lounging in the cockpit and enjoying the sights and sounds. No stereo playing, no conversation really. I had settled in to the steady, melodic drone of the 6CTAs purring along. And then........

There was a definite pitch change in the sound of the exhaust. You know that sound when your dockmate cranks up his generator before he leaves, and after 30 seconds or more there is still ZERO water being ejected from his exhaust? Yes, that sound. You know he fried his impeller and the engine is seconds away from shutting itself down. Well, I heard that sound at full cruise. For some reason, my first reaction was to look at the Starboard Engine Temperature. The needle usually sits about a half of a needle thickness above the 160 Deg F line. Well, when I looked at it, it was reading 180 Deg F and climbing! I actually could detect the needle moving. I immediately throttled back to idle, took both engines out of gear, and shutdown the Starboard engine. By my estimation, the engine temperature was 190 Deg F. The High Temperature Alarm has not been triggered yet. I was feeling VERY lucky.

We limped about 12 miles back home on the Port Engine. The boat handled much better that I thought. Docking was interesting, but I had called ahead and had two people on the dock to compliment my two deck hands at the forward bow and midships.

When the engine cooled off, I went down to the ER and did the simple checks: Strainer, Thru Hull, Sea Cock. Water was flowing just fine.

I came back to the boat this morning to address the issue. Removing the pump to facilitate working on it (this is the Starboard, so it is the PITA one) helps. When I remove the cover plate, I find a piece of the "key". I think it was in the vanes, but I really can't remember. My bolt-impeller puller wouldn't work for two reasons: the threads were all galled up on the impeller, and the impeller was turning on the shaft.

After removing the impeller, it became obvious that the key had broken thus removing the "connection" between the shaft and the impeller. A visual inspection of the shaft didn't reveal any obvious damage or deformation of the keyway. This impeller, and key, was changed in July 2018. There are only about 50 hours on the impeller, and one winterization, where the impellers are left in place.

These are Sherwood 17000K impellers for the Sherwood P1730C pump.

I completed the impeller change and put everything back together and tested the engine. Good water flow. But I have to admit that this episode will be in the back of my mind when cruising at speed!

Has anyone ever seen or had this mode of failure?

Is this just another reason to switch to the SBMAR pumps which have splines instead of a key? (I think that I know the answer to this one)

Thanks for indulging my story. I look forward to your comments and insights.

Jaybeaux

 

https://www.sbmar.com/product/20-gear-oil-cooler-hx-s-s-pipe-1-75/

$175

Jaybeaux

 

If i remember reading it correctly, that was one of the (many) improvements to go to splines, avoiding a key break. I personally, have not experienced it and have been happy running SMX for the past 2 years.

Good job hearing the tone difference and reacting as fast as you did. Being "one with the sounds of the boat" saved you from a much more critical situation.

 

Order from SB marine....any idea where this part is on quickserve? Would like to find all the hoses for the RW system.
Thanks

 

I doesn’t sound like the key sheared? With the wear plate how did the key get out of the key way? Or is that the question?

 

I sense that you're trying to tell me something, but I'm not getting it. Talk to me like I'm 6.

 

The key is normally 2 or so inches long. The "remains" of the key is in one of the pictures. You probably have the other piece(s) in the trans cooler. Worh breaking it all down until you find it.

 

At first glance I'm thinking that should not be able to happen. Those keys are/should be a pretty close fit in the keyway. I'm wondering if it was the correct key and whether or not after the key was installed was the plastic cap put in place to keep it from working out endways. Was there scoring on the pump end cover? Item 5 is the plastic cap/keeper

 

Thinking the same on the plastic cap....was it installed?

 

Pic of the failed part....SB says they sell quite a few of these. Also said you can make this out of PVC and flame a bend into the pipe.

 

Blueone/Woody/EKM....I think you guys hit the nail on the head. When I changed the impeller last year (my first time), well, I don't think I need to say anymore. I am having a vague memory of forgetting to install the plastic cap. When disassembling today, there was no plastic cap. I'm beginning to think that the key ground itself away on the "cover", Part #3 in Woody's picture. Finally, it just fell out. What is left is very similar in length to the depth of the plastic cap.

I think I'll remove the cap again tomorrow and look closer at it and perhaps even flip it.

Thanks for all the comments.

Jaybeaux