Official Cummins 6cta 450C thread

ZZ13 said:
Figured that would be the answer. Now I have another science project - like I need another one of those.
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Ha. None of us need those
I wouldn’t loose any sleep over it unless it turns really hard (alignment issues)
 
my3sons said:
Ha. None of us need those
I wouldn’t loose any sleep over it unless it turns really hard (alignment issues)
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No. I can turn it by one hand up near the transmission. Just it's more snug than the other side. I'll chalk it up to cutless bearing factory tolerances.
 
my3sons said:
I agree with Bill. You’re most likely looking at fuel delivery based on what you are saying. You should know how accurate your tachs are, you say they could be off a hundred, could they be off 200? Because high idle should be 3000 +/- 20 rpm’s or so. 2800 isn’t making it.
Things like this are a lot easier to get to the bottom to in person than over the internet. We’ll help best we can but....
Make sure your throttles are advancing all the way to the stops and a little into the spring. Make sure the fuel shutoff solenoids are opening fully. Change the secondary filters on the engine.
Let’s see where we are then. Good luck
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Racors on the problem (port) engine changed. On engine also changed. The Racors were dirty. But i didn’t notice any change in the engine at the dock. It’s later on the day and I’m here solo, so no test run. But same RPM’s at the dock as pre fuel filter change. I went ahead and changed the SB Racors, too. Just for fun. I didn’t do the on engine filter there however. I’ll take her for a spin tomorrow and see if there’s any change.

Btw, the spec for these engines is 30 micron Racors, right?
 
scooper321 said:
Racors on the problem (port) engine changed. On engine also changed. The Racors were dirty. But i didn’t notice any change in the engine at the dock. It’s later on the day and I’m here solo, so no test run. But same RPM’s at the dock as pre fuel filter change. I went ahead and changed the SB Racors, too. Just for fun. I didn’t do the on engine filter there however. I’ll take her for a spin tomorrow and see if there’s any change.

Btw, the spec for these engines is 30 micron Racors, right?
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Yes, I use the 30 micron Racor and the FF5285 spin on filter.

This is probably irrelevant but you could try switching the port to pull from the starboard tank to rule out something wrong inside the port tank.
 
scooper321 said:
Racors on the problem (port) engine changed. On engine also changed. The Racors were dirty. But i didn’t notice any change in the engine at the dock. It’s later on the day and I’m here solo, so no test run. But same RPM’s at the dock as pre fuel filter change. I went ahead and changed the SB Racors, too. Just for fun. I didn’t do the on engine filter there however. I’ll take her for a spin tomorrow and see if there’s any change.

Btw, the spec for these engines is 30 micron Racors, right?
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On my 6CTA's I use the 2040N-30 (30 micron) Racors, and then the spin ons are FF 5285 which is 20 micron.
 
ZZ13 said:
Yes, I use the 30 micron Racor and the FF5285 spin on filter.

This is probably irrelevant but you could try switching the port to pull from the starboard tank to rule out something wrong inside the port tank.
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Nothing is irrelevant at this point. And it’s funny you mention that. I double checked and I was drawing from the correct tanks. And just for grins, I went ahead and changed the Racors on the starboard engine. I may try swapping tanks tomorrow. I agree that’s a bit of a longshot, but it’s worth checking out. It’s easy to do.

The thing I’m not comfortable doing myself is checking the throttle linkage and the control solenoid. I know those are rather easy things to do, but I’ve never done them and everything is always harder and longer the first time.

“That’s what she said” I I may try swapping tanks tomorrow. I agree that’s a bit of a longshot, but it’s worth checking out. It’s easy to do.

The thing I’m not comfortable doing myself is checking the throttle linkage in the control solenoid. I know those are rather easy things to do, but I’ve never done them and everything is always harder and longer the first time.

“That’s what she said“
 
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scooper321 said:
Nothing is a relevant at this point. And it’s funny you mention that. I double checked and I was drawing from the correct tanks. And just for grins, I went ahead and changed the Racors on the starboard engine. I may try swapping tanks tomorrow. I agree that’s a bit of a longshot, but it’s worth checking out. It’s easy to do.

The thing I’m not comfortable doing myself is checking the throttle linkage and the control solenoid. I know those are rather easy things to do, but I’ve never done them and everything is always harder and longer the first time.

“That’s what she said” I I may try swapping tanks tomorrow. I agree that’s a bit of a longshot, but it’s worth checking out. It’s easy to do.

The thing I’m not comfortable doing myself is checking the throttle linkage in the control solenoid. I know those are rather easy things to do, but I’ve never done them and everything is always harder and longer the first time.

“That’s what she said“
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Other easy stuff you can try is all the permutations of the Racor lever, if you haven't already. I only use one Racor. I don't use the "all" setting.
 
I'm the odd ball that runs 10M in the racors, but 30 is recommended, and what you should run.
You should have vacuum gauges on your racor housings, assume they are working and not showing a plugged condition? Eliminates tank restrictions etc.
 
my3sons said:
I'm the odd ball that runs 10M in the racors, but 30 is recommended, and what you should run.
You should have vacuum gauges on your racor housings, assume they are working and not showing a plugged condition? Eliminates tank restrictions etc.
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my prev owner and a few guys I boat with that have 400’s run 10’s. Nothing wrong with that as long as you change them frequently.

I do have the gauge. I don’t believe it’s showing any issue:
452650BC-7787-4B23-999E-646D4D88B4E9.jpeg


And Bill, yes, I’ve tried using one or the other or both. No change. Normally, I run on just one, too.
 
That has to be read while underway. Maybe sometime in the future you can get a drag needle type to replace it with so you can se what it was while you were running.
DSC_1037 (2).JPG
 
my3sons said:
I'm the odd ball that runs 10M in the racors, but 30 is recommended, and what you should run.
You should have vacuum gauges on your racor housings, assume they are working and not showing a plugged condition? Eliminates tank restrictions etc.
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Not so odd. I run 10m in the Racors. The mechanic that works on mine (the only one) recommends and he knows more than most have forgotten. Also the marina where I fuel uses 10m in their system. Also considering additional filtration similar to what Tony suggests on Sbmar.
 
Where is everyone buying your oil filters LF9009 ?... I just paid $75 for two.... seems a bit steep
 
Blueone said:
Where is everyone buying your oil filters LF9009 ?... I just paid $75 for two.... seems a bit steep
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Amazon has 2 for $66.80 and 3 for $101. I was buying all of my QSC filters from Amazon. Free shipping is nice too....This is where Cat has Cummins beat...Cat filters are quite a bit cheaper.....

Bennett
 
For those of you interested my progress, it does not appear to be an engine issue. At least not at the moment. It's been bugging me that I was able to get high RPM unloaded and not when under load, which would seem to imply a drive problem instead of an engine problem. I had a diver out today and he confirmed the bottom of my boat was clean, as were the shafts and props. However, while the SB prop spun freely, the P prop was quite stiff. So it may very well be that cutlass bearing I mentioned previously. I'm taking the boat to be hauled and have the bearings (both) checked, the shafts checked and the engine alignment checked. I haven't hit anything to my knowledge, so I'm thinking it's still likely the bearing, but we'll see. This doesn't appear to be an engine issue any longer, so I'll take this discussion over to the 400DB forum. I'll bring it back here if it becomes an engine issue.
 
The fact that you can get no load RPM to it's max and your loaded RPM does not reach it's max does NOT eliminate an engine issue. It takes significantly more fuel (and air) to get max RPM on plane than in neutral. Still could be a fuel delivery issue, or an air intake issue <turbo, aftercooler, hoses, etc>. Have you looked inside your exhaust hose? I have seen where they have delaminated on the inside causing blockages at higher RPM that will cause similar issues.
 
LMBoat said:
The fact that you can get no load RPM to it's max and your loaded RPM does not reach it's max does NOT eliminate an engine issue. It takes significantly more fuel (and air) to get max RPM on plane than in neutral. Still could be a fuel delivery issue, or an air intake issue <turbo, aftercooler, hoses, etc>. Have you looked inside your exhaust hose? I have seen where they have delaminated on the inside causing blockages at higher RPM that will cause similar issues.
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I totally in agreement with you, Larry.

Scooper,
If you can spin the prop by hand, even if it feels a bit stiff, there's just no way 450 ponies will care.

If your engine makes 3000RPMs at no-load, you checked off throttle linkage, governor setting and the HP pump rack reaching WOT. All of these do not indicate adequate fuel supply during the load.
 
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