671 TA smoke

[Scarlett]

Just surveyed a 49 Gulfstar with 671 TA engines that started from cold immediately with very little smoke for about 5 seconds. As soon as we started running up the RPM’s they started smoking very black smoke at about 1500 and it did not clear up at all. Supposedly all 4 turbos were just serviced, what ever that means. The owner never ran them over 1200 for 4 years. You guys always have great ideas in this area, what do you think? John

 

[racclarkson@gmail.com]

Smoke at RPM (black) could be lack of air. Turbos, clogged after cooler?

 

[Boatsb]

Get a good engine survey.

It's not a good idea to armchair survey engines. It may be simple but it also may be a big cost item.

You already determined their not running right.

 

[rplatt7]

Just surveyed a 49 Gulfstar with 671 TA engines that started from cold immediately with very little smoke for about 5 seconds. As soon as we started running up the RPM’s they started smoking very black smoke at about 1500 and it did not clear up at all. Supposedly all 4 turbos were just serviced, what ever that means. The owner never ran them over 1200 for 4 years. You guys always have great ideas in this area, what do you think? John

From past experiences check the emergency air shut offs.

 

[kelpy]

Need a bit more info. Did the engines ever reach rated WOT rpm during the seatrial? Did both engines exhibit the same behavior at the same RPMs?

 

[Scarlett]

Kelpy, no and yes did not hit WOT and yes both engines

 

[kelpy]

1500 RPM is about where the turbos start to make boost.

If this was my problem, I would -

1. Assure that the bottom and running gear are clean.

2. Run a scope down the air side of the aftercoolers to see if they are plugged up.

3. Check the propeller size. Some people think that putting oversize props on the boat helps improve fuel economy at displacement speed/RPM. It doesn't work out that way.