Richard O
08-04-2008, 02:08 AM
I am in the late stages of commissioning a new trawler (126,000 lbs. displacement) equipped with dual John Deere 6068SFM-50 diesels; 267 hp. The engines are new - approx 40 hours total.
Propellers are 32” diameter; 24.5” pitch; four blades - and have been used successfully on similarly configured boats.
The engines run well and smokeless in general operation.
BUT, when put into gear and quickly but briefly powered up - for example to generate a brief burst of power during docking - they emit a very, very dense, black plume of smoke from the exhaust.
This has occurred when the engines were hot (after running for a couple of hours, though at low power settings for the 30 minutes or so prior to the docking). It has also occurred with the engines only slightly warm at the dock (an experiment to test for the smoking condition).
The John Deere service center says this is normal and just advises to be less aggressive with throttle action. I fully understand that especially with turbo-charged engines, aggressive throttle action is not desirable. However, this condition was first observed during normal docking operations with a very experienced professional captain at the helm. The throttle action was not abnormal. My prior experience is with CAT-3208 TAs and I’ve never seen anything like this.
I have attached a video showing the smoke plume but beware: it is 2.9 MB.
So, two questions: first, what is the cause of the smoke plume and, second, is it (as the JD tech says) a normal condition?
Any help would be appreciated.
Propellers are 32” diameter; 24.5” pitch; four blades - and have been used successfully on similarly configured boats.
The engines run well and smokeless in general operation.
BUT, when put into gear and quickly but briefly powered up - for example to generate a brief burst of power during docking - they emit a very, very dense, black plume of smoke from the exhaust.
This has occurred when the engines were hot (after running for a couple of hours, though at low power settings for the 30 minutes or so prior to the docking). It has also occurred with the engines only slightly warm at the dock (an experiment to test for the smoking condition).
The John Deere service center says this is normal and just advises to be less aggressive with throttle action. I fully understand that especially with turbo-charged engines, aggressive throttle action is not desirable. However, this condition was first observed during normal docking operations with a very experienced professional captain at the helm. The throttle action was not abnormal. My prior experience is with CAT-3208 TAs and I’ve never seen anything like this.
I have attached a video showing the smoke plume but beware: it is 2.9 MB.
So, two questions: first, what is the cause of the smoke plume and, second, is it (as the JD tech says) a normal condition?
Any help would be appreciated.