Cummins CTA 8.3 liter bellowing black smoke at 1600rpm?

[fishybusiness]

Greetings everyone, so I took my boat out today and when I reached 1600 rpm is started bellowing black smoke and wouldn't increase in RPM. I am going to check to see if I have a air leak on the pressure side if the turbo, and if that isn't the problem I am going to take the after cooler off to see if there are any obstructions. It has a new air cleaner so I am ruling that out. Any of you motor heads have any other ideas why this is happening? It runs smooth so I am just guessing that the injectors are ok, however I am going to run a can of injector cleaner thru her anyway if the above doesn't take care of the problem. Any other ideas on why this would be happening? Thanks in advance, Matt....

 

[hntrss]

Sounds like it may be a turbo. Pull the air filter and see if there is play in the shaft or obvious signs of wear or water intrusion.

 

[oldshell55]

if you haven't run it for a while, check the bottom, this year was bad for barnacles by me
check no load wot and turbo boost under load

 

[WoundUpMarine]

Id definitely check the turbo, make sure its spinning and you didnt blow a boot off, although you would have heard that more than likely.

 

[bestfish]

Look at the aftercooler, if you take the air connections off and peak in with a flashlight you'll probably see the problem. They are notorious for getting clogged up. There's a really good article on boatdiesel about it. I cleaned mine by boiling it in a turkey fryer with powdered laundry soap. Good luck.

 

[BillD]

you can also read this.

most likely you have an "air to fuel mismatch"

Understanding Low Power Troubleshooting

btw, "if" it turns out you have a turbo issue......double check the exhaust side to make sure water intrusion was not the failure point.

 

[reelrampage35]

Air filter

Did you just replace the air filter???? If it was running fine and then you replaced the air filter and are now having problems start there. Just like first aid, ABC's
Air, breathing(exhaust) and cooling.

 

[[email protected]]

Did you just replace the air filter???? If it was running fine and then you replaced the air filter and are now having problems start there. Just like first aid, ABC's
Air, breathing(exhaust) and cooling.

You don't mention your horsepower rating but judging by the aftercooler comment I'm assuming 430 or 450. I run a paper filter on my 370 B (fleetguard AH19002) as I'm not an Airsep fan, but in the higher HP ratings the paper filters must be the ones with an internal metal screen like the one on the outside or the turbo can pull in paper. These are twice the price of the ones with no inside cage. See if the turbo turns freely by hand, look for obvious charge air leaks, water in or clogged fins on the SWAC, and when idling you can take a 19 mm or 3/4 wrench and a rag and crack injector lines on the pump (P7100 Bosch) Diamond series- not new style common rail 24 valve Quantum ( those pressures are too high to fool with) -and make sure each time you disabled a cylinder it actually slows down the engine. A quarter turn or so is enough to send fuel into the rag and not the to the injector. This can tell you if it's one or two cylinders giving you trouble ( pump, injector maybe) or the whole engine has got a problem which is something common to all 6 cylinders (maybe turbo, charge air loss, fouled bottom) Make sure your isolators are good and your propshaft turns freely. As everyone here has correctly posted, black smoke/ low WOT RPMs are most likely from insufficient charge air pressure or overloading. At 2600 a 430/450 Cummins should have at least 30 PSI at the intake under load, should start making boost at about 1400, and getting like 10 to 15 pounds at 1600. A cheap gauge to a pipe plug in the intake will give you these readings. From the intake to the pump is a small tube that carries air to the air/ fuel control (AFC). make sure it's in good shape. Looks like 1/4 inch tubing. This tells the pump that there is boost and it's OK to fuel. With all the smoke low fuel is probably not whats up but check anyway.

 

[fishybusiness]

Mike, it is a 400 hp, and I just put a new cloth K&N filter on it. The other fiter was really dirty and I think it was a EPI? tapered filter. Just had the boat hauled out here in December from Mass. I pulled both water intake screens on the bottom of the boat in dry dock one to the engine and the other to my pacer pump, and they were not dirty with anything. Going down today and will check everything you have all suggested. You all are a wealth of knowledge and I thank you all for your response. Cheers, Matt, Eureka, Ca. P.S. The boat is a 35 RP with 7k on a complete rebuild 507 twin disk gear with 2:1 ratio. When I sea trialed it there was no smoke even when we took it to WOT.

 

[fishybusiness]

ran some of the ideas posted and here are the findings

Ok, so I pulled the K&N air cleaner off and looked at the turbo. Turbo is dry, no oil, and the shaft is not loose, has normal tiny bit of up and down play. Turbo also spins freely. Took it out and left the engine hatch up and ran it to see what happened. A very little less smoke, but still only 1600-1610 RPM with black smoke. The engine runs very smooth so I don't think it it a fouled injector. So, I took off the after cooler and found some impeller blades but there was never a heating issue. The black smoke tells me that I am getting plenty of fuel and that I must have an air issue. The after cooler water ports were spotless,but it was hard to see if the air/ pressure side was clogged. It wasn't so bad that I couldn't see the fins.
I do see a few very small exhaust leaks, one is at the gasket at the turbo side, and maybe one at the manifold closest to the turbo. While I was out this last time I went down in the engine room and ran my hand all along the pressure side of the turbo and felt no air leak. My next step is going to pressure test the after cooler to see if it is in the after cooler. This will give me the answer to an after cooler problem with air. However, if it is not the after cooler where should I look next? Could the small exhaust leaks be not spinning the exhaust side of the turbo? They don't seem like they are that bad, but I will fix them just because they bug me. Ideas? Thanks, Matt.....

 

[hntrss]

Matt - I am not a mechanic, and there are some seriously good ones on here, but I don't think there should be any play in the turbo shaft. I was told on my Volvo if you can fit a dime between the housing and the blades the turbo was toast ( and it was ). So if there is play in the shaft, then there is clearance. I have a feeling you need one. They aren't that bad for cummins and if you are mechanical you can change it yourself.

 

[Field Tester]

First, remove the mixing elbow off the turbo and inspect the exhaust side of the turbo.. Here's a pic of a turbo off a 4bta with the same problem your having. The problem sounds like a lack of boost. This is what salt water does to the exhaust side of the turbo. It will spin free but wont make any boost.

 

[FPTMarineDiesel]

Matt - I am not a mechanic, and there are some seriously good ones on here, but I don't think there should be any play in the turbo shaft. I was told on my Volvo if you can fit a dime between the housing and the blades the turbo was toast ( and it was ). So if there is play in the shaft, then there is clearance. I have a feeling you need one. They aren't that bad for cummins and if you are mechanical you can change it yourself.

All turbo chargers have some play when static, it is normal. The bearings are designed to be pressure lubricated and need some space around the bearing and shaft for oil to make a barrier and allow the shaft to float. There should not be so much play that when you spin and hold radial that the compressor or turbine wheels make contact with the housings. There should not be soo much axial play that you can fell it clunk back and forth in the cartridge.

Black smoke is more fuel than air, so try running with the air filter completely removed and see what takes place (be sure that there are no loose items around or a lot of loose dust, glass, debris, etc). If this turbo charger is wastegated, be sure that there is not a problem with the wastegate actuator holding the bypass valve wide open all the time. Not sure if you have a mechanical wastegate with a pressure sense line of the compressor housing of the turbo or not? There would be a rubber line going from the compressor side to a wastegate bell and diaphragm assy. that would be attached to a lever arm and a link to open a bypass door in the exhaust housing. If that is all mechanically sound, then there must be a restriction or fouling of the cooler core. Potentially you are also dumping boost air to atmosphere but that would be evident with a high pitch screaming sound when under load where the air is escaping through a hose or clamp connection..

 

[BillD]

Matt,

All good advice here.

You are spinning your wheels here until you do these tasks.

You either have a non spinning turbo (rusted up like in the pic here) or your have a clogged after cooler.

1. Remove the exhaust flange from the turbo, take and post some pictures here.

You wont get this sorted out until you remove the exhaust flange and look @ the turbo. If it looks like the pic posted here you have sea water intrusion and exhaust design issues that will be need to be fixed.

2. Remove and take apart the after cooler. Take some pics and post here.

Re-assemble as seen in the article.

Aftercooler Maintenance - Cummins



3. Check the turbo waste gate, but on boatdiesel forum I don't recall stuck waste gates on a 6CTAs as being problematic.

Do this and get back to us.

FWIW, Bill D

 

[Field Tester]

Bill that turbo in the pic spun free. But enough metal rusted away where it no longer made any boost. So my point is, dont be fooled by a free spinning turbo. You HAVE to take the exhaust apart and look at it.

 

[BillD]

Bill that turbo in the pic spun free. But enough metal rusted away where it no longer made any boost. So my point is, dont be fooled by a free spinning turbo. You HAVE to take the exhaust apart and look at it.

Bingo,

I totally agree with you.
There are 100s if not 1000s thousands of posted threads on "sunken turbos", clogged after cooler cores etc. etc. over on boatdiesel forum. Cummins, CAT, Yanmar, Volvo..doesn't matter what make...turbos drinking salt water over time, after coolers being neglected etc. etc.

As I posted, Matt's "guessing" until he gets components apart.

 

[BillD]

Matt,

All good advice here.

You are spinning your wheels here until you do these tasks.

You either have a non spinning turbo (rusted up like in the pic here) or your have a clogged after cooler.

1. Remove the exhaust flange from the turbo, take and post some pictures here.

You wont get this sorted out until you remove the exhaust flange and look @ the turbo. If it looks like the pic posted here you have sea water intrusion and exhaust design issues that will be need to be fixed.

2. Remove and take apart the after cooler. Take some pics and post here.

Re-assemble as seen in the article.

Aftercooler Maintenance - Cummins



3. Check the turbo waste gate, but on boatdiesel forum I don't recall stuck waste gates on a 6CTAs as being problematic.

Do this and get back to us.

FWIW, Bill D

Bingo,

I totally agree with you.
There are 100s if not 1000s thousands of posted threads on "sunken turbos", clogged after cooler cores etc. etc. over on boatdiesel forum. Cummins, CAT, Yanmar, Volvo..doesn't matter what make...turbos drinking salt water over time, after coolers being neglected etc. etc.

As I posted, Matt's "guessing" until he gets components apart.

Matt,

Did some research through Seaboard Marine (Tony Athens),

The 6CTAs do NOT have waste gates on the turbo.

Check the exhaust side of the turbo and the after cooler core.

 

[whitewater1787]

FWIW I had exactly the same problem a few years ago on a different boat with a Yanmar 4LHA DTP. Went out for a ride after not running boat for almost 2 months and as I brought up throttle at about 1600 rpm started pushing all kinds of black smoke, pushed up throttle to wide open and more black smoke and only got up to 1800rpm (normal WOT was about 31-3300rpm). Long story short after checking all the things that would normally be suspect, turbo, air filter, etc. an old salt in the same creek asked me if the prop was ok since it was a bad barnacle season, boat ran fine the last time I used it so I didn't think this would be it. After pulling my hair to no avail I decided to pull the boat and to my surprise the wheel was totally encased in barnacles, almost unrecognizable as a propeller. Needless to say clean off the barnacles, back in the water, end of story boat ran fine. Couldn't resist posted this if I didn't experience this I wouldn't have believed it....Good Luck

 

[fishybusiness]

black smoke problem low rpm update.

So, as I mentioned before I took the after cooler off and inspected it. It didn't look bad so I put it all back together and re-tightened all of the hose clamps. Today my cummins friend and mechanic had time after work to put the pressure gauges on the intake and the other side of the after cooler. As I went down the bay I throttled up and low and behold she ran like a striped ass ape reaching full RPM! So, I guess that it was in fact a air leak in the pressure side of the turbo and tightening the clamps must have rectified the problem. WOT was 2550 and the smoke was mostly gone. Hard to tell because it was dark, however I am going to take her out tomorrow and re-test just to make sure. She hasn't been run for several months, and I want to put her under a load to see if things clean up. What a relief! Now I can move on to the more fun stuff like upgrading the electronics and other details. Thank you all, I have learned so much from all of you and I am still learning. Going to clean up the engine room, re-paint so I can see any new leaks, and map everything out to get to know how everything is run. Glad to be a member here as you all are a big help and save me time and most of all money. Best regards to all, and thanks again for all of the input! Cheers! Matt

 

[BillD]

Problem solved.