Man CR900 valves & injectors

Had a lot of soot this trip over to the Bahamas from both engines. We towed (cruise speed of approx. 21knts) the 19ft tender and were loaded down with gear for two months upon arrival at Green Turtle there was soot all over bridge, cockpit, instruments, transom, etc. Had just changed all racors and internal fuel filters before leaving Ponce.
Going to have the engines looked at when we get back to Ft. Pierce. Called Man (Ace Marine) and they said they would check the valves first (they were adjusted on the 1000hr service) and motors currently have 1100 hrs so short period. Next he said they would check injectors. Anyone have a rough idea what the injectors run for the common rails if they have to be replaced?
Thanks, Skip

Anywhere from 1750-1900rpm. I agree on the valves hard to believe they are the issue. Much more likely the injectors. These engines have always smoked slightly more than most common rails I have been on.

Possible but unlikely since its both engines. I have tried running both ways running with blowers on and off. Mostly off. Owned boat for 7 years.

Bill,
My normal load % is around 75-76% and this trip it was in the high 80s. We did not have a following wind actually a head wind. The boat has always had a station wagon affect that certainly doesn't help this issue. Since 05 was the first year of the common rail Man maybe they are just not as finely tuned as the new ones.
If it was an exhaust leak wouldn't I smell exhaust in the engine room?
Thx, Skip

K1W1,
I did run over this trip (approx. 15hrs) using the blowers if that could have created this issue.
Thx, Skip

Capt J,
With clean bottom and props it turns 2360 rpms. When I got the boat in 08 the props were 4 blade 28x40 and the load was high with full fuel and water and could not turn up to 2350. Had the props tuned and pitch reduced to 37.5 and since then been able to turn up to 2360rpm.
Did run with the trim tabs partially down as this boat rides bow high normally although we had a lot of cases of water, beer, etc up front. Many of the 43 Cabos have the R800 6 cyc and have a lot less weight in stern of boat. Also all 700 gals of fuel are under cockpit floor.
I only tow the boat once a year when we go to the Bahamas. That's a total of approx. 30 hrs there and back.
Changed racor fuel filters (10 micron) when we got here and they were changed before we left.

RC,
They were not swells it was a sloppy mixed sea out of the east.

SeaGull
Thanks for the info. Just curious what kind of boat you had that ran that high 80% at normal cruise. This boat has a deep vee from bow to stern and weighs about 48k pounds.

Did you have the oil cooler gaskets replaced on both engines? Had to do that around 400 hrs and everyone I have ever talked to with those engines had to have this done.
So you were running most of the time at 2000rpm or 80% load. I have not run at 2000 very much because I thought that might be too hard on the engines. At 1900 running about 26 knts.

Capt J,
Thanks for the suggestion and believe me I'm not looking to spend money although certainly don't want to damage the engines. Ironically yesterday I talked to two boat owners over here that have the same Man CR900 engines. One a 58 SeaRay like Sea Gull owned and the other a Viking 45 both about same years. Neither one smoke or produce soot according to their owners although they were not towing. I will wait for awhile after we get back and see how the engines do. My engines have always produced some soot even on a day trip the transom needs to be cleaned well. Maybe a lot of that is the station wagon effect that we have on this boat.
No one has ever told me 80% load is where they should be run. Always thought that was too high and you should try to keep below. Great to know.
Do you recommend any injector cleaner or are most just bs?

Sea Gull,
That's about the same hours we put on our engines a year. Appreciate your feedback and to learn running 80% load is fine. Will see how the engines perform after we get home and do some local trips.


Thanks, Skip