Hi,
After propping down from 35ā to 33ā and retuning and balancing the props I have experienced some changes which Iāll post here.
The port and starboard engines are running closer temps at 1820 RPM cruise and 23 MPH speed:
Temps @ 163p / 165s
GPH 17.6p / 18.9s
The engines are running better than before at all RPMs and make rated RPM of 2300 on both with WOT of 2360p / 2330s.
Tony, in answering your response. Yes, I did repitch my props and it did make a big difference in the GPH, I saved a total of 5GPH between the two engines.
Before reducing pitch, as I mentioned in the original post, I changed the fuel filters including the last chance filters. I will also mention that there was only a slight vacuum on the Racor filter guage, nothing out of the norm. The bottom was also cleaned. The black āparticlesā were residue from the coolant leak that was repaired. I also mentioned that in the original post I had to replace the coolant tube that runs from the expansion tank to the top of the thermostat housing. Tony, I had called Brad, your parts guy to buy the tube. After describing it in detail to him, he said he would send a diagram via email in order to make sure it was the correct part? How many coolant cross over tubes that run from the expansion tank to the thermostat housing that run above the heat shield pan are there? Nevertheless, I never got the email and bought the $750 tube, O rings and new bolts from another shop. Just thought you should know as the owner why I didnāt buy the parts from you. Apparently, there was a very small crack in the flange weld of the coolant tube that had ādrippedā down onto the exhaust manifold causing it to ācookā becoming a paste. The paste eventually became hard and dropped down into the bilge in a small granular particals. After awhile there was no more evidence of these particals. Iād also like to mention at no time did my engines overheat, I watch my SmartCraft SC5000 screen temps, oil psi, GPH, RPMS And volts any time I run the boat and check constantly while running
What prompted me to search for the ārootā of cause of the original issues was this: the starboard engine always ran very close to the port engine on all data since new (2004). So, It was puzzling as to why the change in temps, GPH, RPM at WOT? Iām NOT saying that propping down wasnāt needed, it was and the engines run smoothly without breaking a sweat. I lost about .05 MPH at 1820 RPM, no big deal.
In my original, original post I mentioned that I had the after coolers removed, benched, cleaned at 1187 hours. The issues that prompted my post was immediately after I had the coolers done. I found out the starboard side cross over to the cooler had a very slight leak. I found this out by going into engine compartment and putting my hand under the cross over. When I spoke to another boat owner with the exact same year, make, model, engines and problem from the āother forumā, he suggested that this is where I should look because he had the same issues and this was his fix.
Evan though ALL gaskets and āOā rings were replaced (and purchased by me through SB Marine) by my mechanic, who is a Cummins trained mechanic with 40 plus years as diesel mechanic. These things happen and it could be a bad gasket, incorrectly installed gasket, bad surface. I get it, stuff happens! Iām just upset with the local Tech who told me there was nothing wrong with the starboard engine and then after trying to reflash the ECMās to a recent version (10/17) couldnāt reflash the starboard side causing me to pay a $4000 shop bill and still have all of the same issues!
I will say this, Tony, you were absolutely correct with the prop issue! Thank you. Reducing pitch was needed with or without correcting the original issue (which was causing the check engine light to come on and throwing a fault code of low intake pressure) higher temps and more fuel burn.
Thank you,
Tom Mann
Bow Tie
.
