Official Cummins 6cta 450C thread

[Strecker25]

Thanks all. Mark, that’s exactly what these looked like.

the aftercooler was bright white with no brown like I’ve come across on some others so that was nice to see as well. Engines were clean otherwise, although I did notice NAPA filters instead of oems. Not necessarily a bad thing, just an observation

 

[EKM]

Hi All,
Just started a two week cruise and my starboard engine is low on RPMs. Port pulls 2700 and the starboard pulls only 2450. Just finished a 6 hour trip and didn't notice any problems....was cruising at 2100 or 2150 both engines. This morning, the starboard engine was having a hard time spooling up. Took a detour and picked up new filters (primary and secondary) and changed them out. No real difference. Checked the props for any damage or picked up lines...all good below. Checked the turbo boots for leakage while at 2100rpm...nothing.

Both engines are running same temps. Could tach be off as I was surprised the Port pulled 2700 with a full load of fuel and full water. Boat probably is at 41,000 lbs. Does seem like the Stbd is struggling to keep up. The fuel arm is more advanced on my STBD engine (maybe 1/4" from the stop at 2100).
How do you trouble shoot from here?

 

[NotHerDecision]

Did you check the hoses and clamps after the turbo? Of one of these is leaking it can cause exactly what you describe. They running with the engine hatch open and listen to the turbos spool you and is the sound the same.

 

[EKM]

Did you check the hoses and clamps after the turbo? Of one of these is leaking it can cause exactly what you describe. They running with the engine hatch open and listen to the turbos spool you and is the sound the same.

yes....turbo hoses checked at 2100 rpm and could not feel a leak. I could also replace them as I still have the old ones on the boat (replaced turbo hoses at the beginning of the season. Is there a way to check boost pressure?

 

[ZZ13]

yes....turbo hoses checked at 2100 rpm and could not feel a leak. I could also replace them as I still have the old ones on the boat (replaced turbo hoses at the beginning of the season. Is there a way to check boost pressure?

See this post and the one following it regarding boost gauge.

http://clubsearay.com/index.php?threads/official-cummins-6cta-450c-thread.77886/page-30#post-1119668

I rebuilt both my turbos recently. Rust buildup on inside of turbine housing restricted boost and spooling parts were generally worn. You could remove both engines air filters and spin each compressor blade by hand. See if they both spin with the same freedom. You would need to remove exhaust elbow to see inside turbine housing. Sometimes that's hard to do without cutting off the four bolts as they can be rusted up pretty good.

When is last time aftercoolers were pulled and disassembled and the air side cleaned?

 

[EKM]

I rebuilt both my turbos recently. Rust buildup on inside of turbine housing restricted boost and spooling parts were generally worn. You could remove both engines air filters and spin each compressor blade by hand. See if they both spin with the same freedom. You would need to remove exhaust elbow to see inside turbine housing. Sometimes that's hard to do without cutting off the four bolts as they can be rusted up pretty good.

When is last time aftercoolers were pulled and disassembled and the air side cleaned?[/QUOTE]
I pulled and disassembled the aftercoolers at the beginning of the season so they are now fine. That was my next step to pull the filters and check for wear/binding on the turbo.
Thanks for the help.

 

[EKM]

See this post and the one following it regarding boost gauge.

http://clubsearay.com/index.php?threads/official-cummins-6cta-450c-thread.77886/page-30#post-1119668

Hi Bill,
Just read your post on gages....nice. So 20psi boost and need to find adapters and a gage to check out turbo performance on my engines. Might be pretty tough to find my way to the bridge with tubing but can be a winter project. How much did you spend on the parts?
Thanks.
Ed

 

[my3sons]

Hi All,
Just started a two week cruise and my starboard engine is low on RPMs. Port pulls 2700 and the starboard pulls only 2450. Just finished a 6 hour trip and didn't notice any problems....
How do you trouble shoot from here?

If you think it shouldn’t be turning 2700 under those loading conditions, it probably isn’t, you know your boat best.
Also seems hard to believe it would turn up 2700 with the other one not helping much. Let’s get a photo tach and check the tachometers for starters.
Then make sure the throttle arms are advancing all the way to the stops and just a touch into the springs when throttle levers are fully forward.
Then make sure the fuel shutoff solenoid opens and closes crisply and isn’t “lazy”
Next would be to check the high idle at the dock, 3000 rpm +/-.
Good luck

edit: I forgot to ask if your boat speed is in line with what you are used to seeing at 2700 rpm or 2450 rpm or???

 

[EKM]

Also seems hard to believe it would turn up 2700 with the other one not helping much. Let’s get a photo tach and check the tachometers for starters.
Then make sure the throttle arms are advancing all the way to the stops and just a touch into the springs when throttle levers are fully forward.
Then make sure the fuel shutoff solenoid opens and closes crisply and isn’t “lazy”
Next would be to check the high idle at the dock, 3000 rpm +/-.
Good luck

edit: I forgot to ask if your boat speed is in line with what you are used to seeing at 2700 rpm or 2450 rpm or???[/QUOTE]
My old boat with Cats had the fuel SV thunk….this one does not (both engines). Will listen further when I can back into ER. Throttle arm on STBD engine is advancing all the way and its noticeable more advanced at cruise of 2100 from the port engine. Agree on the tach to verify RPM.
How do you check high idle? Let engine warm up a bit and then advance throttle?
Boat speed is slower than usual in current condition. Running at 2100 P and 2050S. If put eng sync on, S engine slows down considerably.

 

[my3sons]

First things first. Your talking about rpms that you have no idea if they are correct.
When my tachs crapped out last year, they were reading all over the dial from a few hundred to 3000 rpm.

 

[my3sons]

High idle check: engines up to operating temperature (outside of oil filters measure 160 plus degrees) no IR Gun? Go for a boat ride first. In neutral, advance throttles wide open. Going from memory the range is 2960 to 3020 ??
Call it 3000 +/-.
But if your tachs aren’t accurate...worthless.

 

[ZZ13]

Ed, I paid $200 for the dual boost gauge and about $25 for 100 feet of hose and the fittings.

My boost ranges from 16-20 psi depending on load. The lighter the load the less the boost needed to maintain rpm.

 

[EKM]

edit: I forgot to ask if your boat speed is in line with what you are used to seeing at 2700 rpm or 2450 rpm or???[/QUOTE]
Boat speed is slow but also full tanks and full water.
Removed air sep to inspect turbo...no radial or axial play and spins freely.
I'm currently at anchor at Block Island RI and will test more on my run to Newport RI.
Thanks,
Ed

 

[scooper321]

Shenanigans got her bum cleaned this weekend and we went for a quick spin afterwards. We noticed some black smoke right as we went up on plane. None prior to that, none after. From what I've read, black smoke often happens when there's less air in the air/fuel mixture. So it makes sense that at moment I'm throttling up and just before turbos kick in, that there might be less air than ideal (otherwise, why would we need the turbo's, right?). Still, it got me thinking. This is my 2nd year with the boat, so it's been at least 2 years since the airseps were cleaned. Having time at the dock yesterday, I decided to clean them. Here's some before pics.

Turbo airseps:

Port

Starboard

 

[scooper321]

Here's the after pics, of the cleaned (but unoiled) airseps. I'm not totally thrilled with them - they probably could use another round of cleaning - but they are a lot better. All the particles are gone and a lot of the black crap is, too. I didn't get a chance to fire up the engines afterwards and take her for a test spin, so I don't yet know if the black smoke is gone. But we'll see this week.

One other nice thing: in doing this cleaning, I noticed on the SB engine that the big intake hose that connects the airsep assembly to the engine was loose. Tightened up both hose clamps on it. Probably left loose by my mechanic when they did the after-cooler cleaning this past spring??

 

[ZZ13]

How many engine hours Scoop? It those are original and engines have more than 900-1000 hrs, I'd toss them and get new ones.

 

[scooper321]

How many engine hours Scoop? It those are original and engines have more than 900-1000 hrs, I'd toss them and get new ones.

The engines have about 1400 hours, so I can't believe they are the original ones. The prev owner is actually a friend and was anal about engine maintenance. We talked a bit about the air cleaners as we went over the boat. I just don't remember if they are original. I did get about 4 of those cleaning kits with the boat, however! But you're right. I do plan on swapping them for new ones. I'm thinking I'll wait until I winterize, as that's the next time I'll have the hatches open for easier access to the airseps.

 

[EKM]

edit: I forgot to ask if your boat speed is in line with what you are used to seeing at 2700 rpm or 2450 rpm or???

Boat speed is slow but also full tanks and full water.
Removed air sep to inspect turbo...no radial or axial play and spins freely.
I'm currently at anchor at Block Island RI and will test more on my run to Newport RI.
Thanks,
Ed[/QUOTE]

 

[EKM]

Attempted trip to Newport and found out trans on the Port side was slipping. So not the starboard engine.
At high idle, both hit 3000rpm which checks out the tachs are accurate. Talking to Twin Disc this am to troubleshoot but sound like trans needs to be pulled. Turbo, aftercoolers need to come out too.

 

[my3sons]

Sorry to hear about the gear. That’s a hassle. But glad you got to the bottom of it and can get the fix going. Good luck.