Another CAT 3116 sooting thread

GnrlPatton

Well-Known Member
Jul 12, 2010
708
Maple Valley, WA
Boat Info
Current: 1998 370 Express Cruiser
Sold:1988 230 Weekender
Engines
Twin Cat 3116T
Thought I would start my own since this has gotten worse. I just wrapped up a ~460nm trip from Seattle to Canada and back. I've had a soot issue since I got the boat, but after my return trip yesterday, about 80 miles, the port motor has gotten considerably worse. Attached are 2 pics from after I returned to the dock, previously both motors sooted the transom at about the same rate, and most of this trip that was the case, so I was a bit (OK, a lot) shocked when I saw this on the port side.

Based on input from various threads here, I've:
  • Changed to CAT SAEO oil
  • Removed and cleaned/pressure tested the aftercoolers
  • Removed all bits of impeller/other bits from the heat exchangers and then flushed the cooling system with RidLyme (mostly to help solve a temp increase and white steam from the port motor)
  • Did the fuel system shock treatment from Franks' awesome Fuel Management post
  • Cleaned and oiled the Walker AirSeps

At this point, I'm wondering if my next step is the injectors, do they need to be cleaned/adjusted/tested? The port motor does use about 1/8 of a tank more than starboard over the course of a tank, so I'm pretty sure the sooting is unburned fuel?

Thanks in advance, hopefully I can get this sorted out this fall.
Kevin
 

Attachments

  • Soot-stbd.jpg
    Soot-stbd.jpg
    89.6 KB · Views: 246
  • Soot-port.jpg
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    118.2 KB · Views: 255
Last edited:
Sorry about the picture orientation, not sure how that happened...
 
You don’t mention this above, so I’m wondering if you have cleaned or replaced the air filters?
 

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