Official Cummins 6cta 450C thread

LMBoat said:
i just had to do the turbo to exh manifold gasket for same reason. I could see my leak. I was not sure how much coolant to drain, so I just drained it all (and put it back in after repair). As engine repairs go, not bad. And leak is fixed.
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Well, think this might be my issue. Betting that because I had at least one stuck-open t-stat before that I was probably not reaching full coolant system pressure and now found a weak gasket. As you point out, at least it is easy to get at.

Will try the towel method next time out to confirm. May rebuild/replace the turbo too. Noticed a big ding in my compressor wheel during inspection last fall. Seems to make plenty of boost though, BUT I KNOW IT IS THERE...ughh. might as well put it back together without known bad issues.
 
Forrestkk said:
Good info. Curious, how much coolant did you have to drain to change that?
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I have a 7 gallon bucket. I just drain it all into it and then siphon it back in afterwards. Follow the instructions on sbmar to use high temp RTV on the gasket. I tried it without it and it still leaked with the new gasket.
 
Forrestkk said:
Well, think this might be my issue. Betting that because I had at least one stuck-open t-stat before that I was probably not reaching full coolant system pressure and now found a weak gasket. As you point out, at least it is easy to get at.

Will try the towel method next time out to confirm. May rebuild/replace the turbo too. Noticed a big ding in my compressor wheel during inspection last fall. Seems to make plenty of boost though, BUT I KNOW IT IS THERE...ughh. might as well put it back together without known bad issues.
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There’s a good turbo rebuild guy in West Palm. PM me if you want his number.
 
[QUOTE="Forrestkk, post: 1327174, member: 60611" Noticed a big ding in my compressor wheel during inspection last fall. Seems to make plenty of boost though, BUT I KNOW IT IS THERE...ughh. might as well put it back together without known bad issues.[/QUOTE]
There is a notch in the hub of the turbo wheel. Not sure if that is what you are referring to. Right under the nut.
 
my3sons said:
[QUOTE="Forrestkk, post: 1327174, member: 60611" Noticed a big ding in my compressor wheel during inspection last fall. Seems to make plenty of boost though, BUT I KNOW IT IS THERE...ughh. might as well put it back together without known bad issues.
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There is a notch in the hub of the turbo wheel. Not sure if that is what you are referring to. Right under the nut.[/QUOTE]

Oh no, something went through it, multiple blade dings. If that was an aircraft compressor it wouldn't fly, maybe could blend them out. Amazingly, it makes plenty of boost.
20210930_160609.jpg


I'm thinking about buying a reman turbo so I don't have the down time on turn around.

Any thoughts? Seems as though you can get them for around $2k if you hunt.
 
Forrestkk said:
There is a notch in the hub of the turbo wheel. Not sure if that is what you are referring to. Right under the nut.
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Oh no, something went through it, multiple blade dings. If that was an aircraft compressor it wouldn't fly, maybe could blend them out. Amazingly, it makes plenty of boost.View attachment 127352

I'm thinking about buying a reman turbo so I don't have the down time on turn around.

Any thoughts? Seems as though you can get them for around $2k if you hunt.[/QUOTE]
Ouch!
I have not had to deal with turbos on the boat yet. Can’t help. Others here can maybe help. Some of the salt guys have changed turbos. Good luck.
 
I wouldn't run that period.

You run significant risk if that wheel is 1. out of balance and strikes the housing or 2. decides to break apart due to stress risers.

Each failure mode will surely cause significant damage to your engine internals. They should be able to rebuild that for a fairly decent price.
 
douglee25 said:
I wouldn't run that period.

You run significant risk if that wheel is 1. out of balance and strikes the housing or 2. decides to break apart due to stress risers.

Each failure mode will surely cause significant damage to your engine internals. They should be able to rebuild that for a fairly decent price.
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Appreciate the input.

I am confident it'll be fine as it has been that way for along time. Not sure how long, but sure it happened before my time. .

Agree, both your observations are valid if it let's go, but there is no play in the wheel at all so likely it is balanced enough or that bearing would be shot. I also keep an eye on it and make sure nothing looks different and I don't see any cracks developing.

With the leak, will force me into fixing it.
 
scooper321 said:
thanks. So these are restriction indicators? Which size do our engines use? They offer 3 sizes, 15”, 20” and 25”
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I’m not sure the restriction indicator is that important. When my factory filters got too clogged for cleaning to help, the engine was blowing out black smoke from lack of air and the restrictor didn’t pop.
 
ZZ13 said:
I’m not sure the restriction indicator is that important. When my factory filters got too clogged for cleaning to help, the engine was blowing out black smoke from lack of air and the restrictor didn’t pop.
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Yeah. We broke the cover on one working on the port impeller. Got a cable tie on it now. I’ll try to decipher markings on it to see if I can tell which one it is.
 
scooper321 said:
Yeah. We broke the cover on one working on the port impeller. Got a cable tie on it now. I’ll try to decipher markings on it to see if I can tell which one it is.
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One of mine broke clean like that and I just super glued it back on. Guess it’ll work. I probably don’t care. But it looks normal.
 
ZZ13 said:
One of mine broke clean like that and I just super glued it back on. Guess it’ll work. I probably don’t care. But it looks normal.
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Turns out, I had a spare. My prev owner left me with SO many spares. I don’t always remember what I have!
 
Good Morning Guys, my first post on the Cummins 6cta thread. A boat I am looking at has an engine with a relatively minor oil leak in the front of the engine. I was poking around in the engine room when I was being shown the boat, but it was tough to tell where it was coming from. Didn't look like the oil pan. It was collecting and then dripping from the bracket that bridges the front of the engine right under the the belt shroud, if that makes sense. Engines are low hours, but this boat has been a dock queen. I've live with little leaks with my small blocks, but this is obviously a different level. Any usual suspects? Thanks! Leigh
 
Lhs3422 said:
Good Morning Guys, my first post on the Cummins 6cta thread. A boat I am looking at has an engine with a relatively minor oil leak in the front of the engine. I was poking around in the engine room when I was being shown the boat, but it was tough to tell where it was coming from. Didn't look like the oil pan. It was collecting and then dripping from the bracket that bridges the front of the engine right under the the belt shroud, if that makes sense. Engines are low hours, but this boat has been a dock queen. I've live with little leaks with my small blocks, but this is obviously a different level. Any usual suspects? Thanks! Leigh
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That shroud is easy to remove. Would certainly pull it and look.

The gear case extends under there, and the front main seal on the crankshaft

I've got 1440 on my engines and. No leaks up that way. I have the dip stick dribble on both.
 
Lhs3422 said:
Good Morning Guys, my first post on the Cummins 6cta thread. A boat I am looking at has an engine with a relatively minor oil leak in the front of the engine. I was poking around in the engine room when I was being shown the boat, but it was tough to tell where it was coming from. Didn't look like the oil pan. It was collecting and then dripping from the bracket that bridges the front of the engine right under the the belt shroud, if that makes sense. Engines are low hours, but this boat has been a dock queen. I've live with little leaks with my small blocks, but this is obviously a different level. Any usual suspects? Thanks! Leigh
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I had a similar minor leak in the same spot on my port engine. Turned out it was the water pump. Previous owner (or mechanic) had removed the entire pump to replace the impeller and didn't replace the gasket between the pump and engine. This pump has a gear the fits into the engine and is lubricated from the engine oil ... some just leaked out. It was a small leak so I didn't worry too much about it but found the cause when I replaced the impeller (and took off the pump). This was an easy fix!
 
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