Low power black smoke

[mnoe860]

I am in the process of diagnosing 2001 6cta 2172 on a searay 410 can’t say when it last made clean wot so chasing variables.  Still gathering more information post survey but was hoping to start the conversation as it a new to me boat.  Boat makes manufacture spec speed at wot and is stamped with manufacture wheel size and pitch, all which means little i know but mention it.  Fuel tanks 3/4 full, bottom very little marine growth 3 months in water.  Bare with me Tachs not accurate yet .  With photo tach on balancer Port makes 2440 at wot heavy black smoke when getting on plane cleans up around 2200-2300.  Stbd generally ran clean a noticeable difference but couldn’t safely get between the hot motors to photo tach and shrouds were on. Engine temps lasered and gauges all in range.   New genuine aftercoolers smx both sides (0hrs not pictured) and heat exchanger service kits, clean oil samples current and year ago.  

Valves were adjusted 2yrs 100hrs or so ago don’t know how it was performing pre or post just know they were adjusted, time unkown air cleaners, unknown injectors.

I know I need to get eyes and feel on the turbos, I have no boost numbers, not sure of any leaks, Do I bench test or replace injectors,  Are these exhaust elbows destined to fail per article?  Looking for help on a course of action.  Thanks in advance 

Topic

[Tony Athens]

Doomed to Failure risers–AGAIN !

Your turbo’s have been on a saltwater diet for years..  I am 99% sure the other side will be the same

You need proper risers and new turbos.  Until you accept that, you will not solve your issues

Luckily it looks like you have the room/space/height  to do it right

While you are at it, get your aftercoolers off the engine on on a bench fully dissembled for a proper service

[mnoe860]

PORT Turbo is off

Fresh air side had a small amount of sooty tar like oil, bearings seemed tight and spun free.  The elbow breather at the valve cover with metal pipe attached to turbo seemed to be loose at valve cover compared to starboard.

Exhaust side lots of corrosion much larger gap around the fins 

[Tony Athens]

NEXT STEPS?  This is the sequence

Check tach accuracy at the dock in neural at 2600 RPM, engine warm–Write dowe the numbers

Risers off the turbo and good pics of what things look like inside the exhaust out side of the turbo

Lift the hatch and take good pics showing all from all perspectives–NO CLOSE-UPS–Need to SEE  how much room you have to work with to build proper risers

Props off and taken to a prop shop for a proper scan

[Rob Schepis]

Your turbo is likely corrosion damaged on the exhaust side and done.  As to re-doing your exhaust the Seaboard way, go to the Service tab in the Seaboard Store and go to the custom exhaust fabrication page.

[mnoe860]

I have one more move to make before haul so have not separated the elbow from the exhaust side of the turbo but did get the borescope in and looks like tell tail signs of water intrusion.  See pictures attached scope and port smoke getting on a plane 2485 highest reached wot with phototach, stbd no smoke but 2565 wot.  What are the next steps?  Is a turbo rebuild an option?  And how do I go about having an sbmar smx custom exhaust elbow dimensioned and fabricated?

[Tony Athens]

Another doomed to failure set of exhaust risers

Your exhaust mixers/risers say it all–  100% DOOMED to failure and most likely have done the exhaust side of your turbos in.

Don’t waste any most energy time or money on anything else until the risers of off and I SEE what is inside.

 

 

[mnoe860]

Closed on the boat now after Hurricane Lee fizzled out power washed bottom while hauled and was able to start digging into it.  I calibrated the tachs and verified with photo tachometer powering up with shrouds off no load in neutral at the dock making 700 idle, 1000,1500,2000,2500,3050 rpm on both starboard and port coolant temp 155+ thermal laser of coolant expansion tank, engine temps on gauges approx 160. 

Starboard ran clean.

Port actually produced white smoke around 2000 rpm and up this is the same motor that was throwing black smoke on the sea trial. No visual signs of water in fuel, small amount of growth in racors will clean and replace with 10 micron, and fleetguard secondary.  Removed air filter and turbine spun free and smooth free of any chipping did not get a visual on the exhaust side of the turbo yet. Saddle tanks separate fuel 3/4 full both sides age uncertain.

(all pictures of Port)

[Tony Athens]

Based on your last  post: Get your tachs checked for accuracy——–No load full throttle in neutral at the dock should be 2900-3000 RPM–engine coolant  140F or above   If you can’t figure this out, you need to get a competent mechanic that knows this engines     

[mnoe860]

Thank you Tony, to clarify “new to me as I have no working history” I am about close if this is a walk away situation I value your opinion if there likely is long term damage…that said there is some consideration in the purchase price to account for expenses I will incur.  The surveyor was not a diesel mechanic and was forthcoming in questioning an fuel air issue and questionable turbo health everything BUT internally leaking exhaust risers or riser lift height or angles was in conversation.  And internals we’re not observed. With that said I am trying to get to the bottom of it for going forward.  Tachs were recently attempted to be adjusted and are currently matched and show 2000 at wot so it might just be dip switches if that’s how they are calibrated is this coming from the bell housing, alternator, or synchronizer (which was turned off for trial). I posted serials boat is a New England boat and freshwater for a good period of time maybe 

I have hit your forum postings an articles pretty hard absolute invaluable information and most appreciated. I just reread all your suggested articles and will focus on step by step low power and this case with black smoke and need eyes on internals. Does the order of trouble shooting follow your article suggestions as I am likely over propped and fear the loading condition will have me going in circles. Is the custom fabrication of the geometry of the exhaust riser going to be critical here or is it a part replacement with some modification.   

[Tony Athens]

6CTA 8.3 450 Diamonds

This is how you can sort it out:

 

1. Go thru this link and do not skip anything: https://www.sbmar.com/featured-article/understanding-low-power-troubleshooting/

 

2. Read this–Both engine have “Doomed to failure” exhaust risers–90% both are already  leaking internally–Only wat to tell is to remove them. If this vessel had a survey and this was not pointed out, IMO, the surveyor should lose his credentials

What a Marine Diesel Turbo should look like when Inspected

Marine Exhaust Risers that are Doomed to Fail

3.  post and engine serial number & get you tachs checked for accuracy.. Totally ignore any  written factory specs as to propping, etc,, That was 21+ years ago..

These engine need to “see” and accurate 2700+ rpm with the vessel fully loaded–That is IPPSO FACTO and until you do all the rest and prop them down to make that RPM, you’ll accomplish nothing but get more frustrated, spend $$ wrong,  and do more damage to your engines.. From the looks of things, you  bought a vessel with a well maintained engine room  that externally,  look great–Fresh water boat?

 

Tony

 

 

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