Detroit 671TI on a Trojan 40' Motor Yatch

[Peter Rodriguez]

I have a Trojan Motor Yatch 40' with 2 Detroit 671 TI and they are not reaching more than 1500RPM. The hull is very clean and the propellers too. And are smoking black at 1500RPM. Every filter have being changed. I have 24 X 24 three blades propellers. Could the propellers be the problem? Are they too big or should I clean and check all the injectors first.
Peter

[DOUGNASH]

Not getting full RPM and black smoke means diesel is not being burned and not enough air I believe.

I had this problem with one of my engines

I took off the cover to the aftercooler and found all this crap on the fins blocking air

I took my wet vac and just got all that out of their and back to normal

Mine wouldn't go past 1700rpm when clogged and mucho blacko smoko

Here is what I found

[Peter Rodriguez]

Thanks!! I will take a look into mines and will let you know what I found.

Peter

[Peter Rodriguez]

What prop size do you have on your boat?

[DOUGNASH]

I have 4 blades
28 x 29

[philm216]

I have a 12 meter with Detroits. 4 blade 24 x 25. Doubt it's props to overload to only that rpm. How many hours on the engines? Agree, lack of air or worn cylinders. Both engines perform the same?

[Peter Rodriguez]

Thanks you for your reply. Both engines are doing almost the same the port side is worst. But I am going to open and clean the TI. The engines have 2000 hours I do not think the are worn yet. I think is lack of air.

[comodave]

Open up the hatch(s) to the engine room and see if it gets better. I had a 46' with twin detroits that did not have adequate ventilation built into the boat. Had to add some air intakes.

[prowlersfish]

Thanks you for your reply. Both engines are doing almost the same the port side is worst. But I am going to open and clean the TI. The engines have 2000 hours I do not think the are worn yet. I think is lack of air.

Peter , what is the HP of your 671s ? and what Trojan model exactly do you have ? F40 ? 12 meter ? and what year ?

[DOUGNASH]

Open up the hatch(s) to the engine room and see if it gets better. I had a 46' with twin detroits that did not have adequate ventilation built into the boat. Had to add some air intakes.

Funny you mention that

My boat didn't come with the standard air intakes typically seen on the sides of the hull with the fins facing forward or just open air intakes of any kind

This shot shows the side a bit and no vents besides where the engine room fans vents air out (the picture was taken a few hours before Hurricane Sandy hit, hence all the lines and electrical tape on the fuel tank vent)


But then I realized maybe the engines are pulling air somehow from the lower cockpit
In this picture shows the beginning of the engine mufflers in the top left and right hand corners, right next to them notice those rectangular openings, they had standard plastic vents in them (12 x 18 I believe) I bought new ones to replace from home depot
Maybe the engines draw fresh air through these vents which comes from all the openings around the perimeter inside the lower cockpit?