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94 Detroit 6v92TA 550hp

Old 06-10-2019, 04:33 PM
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$25 subscription to Boat Diesil could be your friend
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Old 06-10-2019, 04:33 PM
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Agreed. Swap turbos.
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Old 06-10-2019, 04:42 PM
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Before I swapped turbos, I'd put a boost gauge on both motors and see how much boost I had on each motor at 1600/1700 RPM.
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Old 06-10-2019, 05:09 PM
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I have the same engines in a 42 Bertram. I once had a similar issue with black smoke and loss of power. The engine would start and idle fine once I got to the ~1800 rpm range black smoke no power. It turned out to be a cracked injector tip. I would first do as the others said and make sure turbos spin freely and both sides of the turbo spin(make sure turbo shaft is not broken). Then I would pull the injectors and get them tested. As for the rpms, the govenor should kick in around 2500-2550 no load. 3000 is scary! WOT full load 2350 a must! For comparison I run 1950 and I'm doing about 21-22 knots burning 34 GPH.
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Old 06-10-2019, 05:33 PM
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Make sure the air box isn't closed. There is a flapper with a mechanical trip release on the blower housing. If it was accidentally tripped, I've seen it cause these symptoms. They're supposed to starve the engine for air and shut it down, but they are almost always warped, don't seal well, and almost never do.
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Old 06-12-2019, 06:30 AM
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Would a bad or broke injector cause black smoke though?
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Old 06-12-2019, 06:41 AM
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Going through this same issue on a 6v-92 DDEC for the Port engine.

Following.

Everything we have looked at so far suggests injectors.
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Old 06-12-2019, 06:51 AM
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An injector can cause this, but not likely. Take rocker covers off and advance the rack on one injector at a time, while holding tube to keep rpms sorta steady. You should hear a good hearty diesel knock each time the advanced rack inj fires. If you hear one that sounds different, that one is likely your problem. Can be messy, some engines throw oil when you do this, can minimize the mess by laying shop rags over rocker gear.

Why did you rebuild the turbos? Was there some sort of problem prior to then? Folks don't just rebuild turbos for fun.

Did both turbos come from the same vendor? Do both turbos have the same cartridge, air scroll and turbine housing part numbers?

Did they rebuild your old turbos, or take them in as cores and sell you other ones?

Could have a wrong turbo.
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Old 06-12-2019, 06:52 AM
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Stuck injector should give black smoke thru whole rpm range, not just at high rpm
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Old 06-12-2019, 07:50 AM
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Port side turbo oil seal was blown so i had that one rebuilt. Then the boat sat for 3 months and didnt start it so I had issues starting it and then when it finally started (lack of fuel im guessing) there was some black soot on the intake side so I took it in to have it looked at and the cartridge was bad. They fully rebuilt my turbos not cores. They are identical and are the ones that came on the engine from factory
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Old 06-12-2019, 08:49 AM
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Have you checked the intercooler for a restriction? I am betting on an air restriction-
When you changed the fuel filters how bad were they?
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Old 06-13-2019, 05:07 AM
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Originally Posted by OneMoreDay View Post
Have you checked the intercooler for a restriction? I am betting on an air restriction-
When you changed the fuel filters how bad were they?
What is the best way to check the inter/aftercooler?

I assume full dissasembly or is there a trick before that?

Last edited by Bryan A.; 06-13-2019 at 06:16 AM.
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Old 06-13-2019, 05:19 AM
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Worked fine before the prop and shaft seal work, and right after it doesn't, generally cracked tips don't happen in a sling, look around and see if something became dis-engaged from a mechanic stepping on something or something fell off.
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Old 06-13-2019, 06:11 AM
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Fuel filters are clean and were clean when i changed them. It does not have an intercooler only aftercooler which i have no cleaned nor checked. I couldn't see it going bad just like that. I did all the work on the seals and engine room work so I know for a fact that nothing was dislodged. I keep gettting suggestions to check the flaps on the shut off flaps and emergency flap so that's where im gonna start, Everything points to air issues not fuel issues since it only does it between 1500-2000 rpms under load.
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