Man CR900 valves & injectors

The station wagon effect definately has a lot to do with it. I ran a 62' Sunseeker to Bimini and back yesterday, 105 NM's, it has exhaust on the side of the hull and we do get some soot behind the exhaust a few feet aft of it. I also ran 2 58' searays with MAN 900's long distances Ft. Laud- CT, and DE to Ohio and there was no sooting and no visible soot or exhaust trail when running. However, injectors are supposed to be yanked and checked at the 1000 hour service, did they do that? But, if they run clean without the tender I wouldn't be alarmed.

On common rails you can do a cylinder drop out test with the computer and verify function pretty well, without necessitating pulling them. However, if you do have to pull one and it's been in there several thousand hours, it might not come out without a lot of heartache, however, having individual cylinder heads does make it not too terrible.

The Man 1100 common rail manual (service interval) I have states doing all of the coolers and after coolers every 2 years or 1000 hours.

89% at 1900 rpms is indeed a very high load factor. CskipR what is the load factor at 1900 RPM when the boat is configured to be able to turn up to 2360 RPM?

I think you are lugging these engines when towing that load. The cylinders are being overfueled and that is what is causing the soot.

Oh, and the computer diagnostic that does the cylinder cut out test, and compression test, could very well not catch a problem that a proper survey with pulling injectors to be sent out for testing, and put a proper compression test guage on each cylinder. Not a bad idea to bore scope each hole as well.

I still think everythings fine and you just were overloaded.

If your normal operation without the tender allows the motors to turn up to 2360, and the % load at 1900 RPM is 75%-76%, then you change to towing a tender and your % load at the same 1900 RPM has now jumped to 89%, you are operating in fuel overload. What were your exhaust gas temperatures?

In any case, operating those engines with such a scenario where they are unable to turn up to their rated RPM is causing damage.

I apologize for not being able to explain why your engines are in overload when towing the tender. Would be easy to explain face to face with a pen and paper.

When you are not towing, you are able to turn up to the rated RPM. 2360 RPM = 100% load. And in this same condition, at 1900 RPM you have about 75% load.

Now, add a heavy load and towing the tender. I would be astonished if you were able to get them to turn up to 2360 RPM. My guess is you will probably only get in the neighborhood of 2075 - 2100 RPM at WOT. So, what is happening is the fuel system has to put a lot more fuel per cycle into the cylinder when you are at 1900 RPM and 89% load. I have heard this called "lugging" or "overfueling", but whatever it is called it is shortening the life of your engines. I believe the soot is from overfueling.

What was the boost pressure when you were running at 1900 RPM and 89% load when towing?

I agree with CaptPkilbride, but at the same token doing it once a year might not shorten their life that much. I would also try 1950 with the tender as it might get more momentum going and both boats fully on plane and load factor might drop. If it doesn't put the trim tabs down and back down to 1850 and see where load ends up.

What CaptP is trying to say is with the heavier load, the boat is now overpropped (in that situation towing the tender) so it's like being on a bicycle and peddling in one gear too high for your speed, takes more effort or too much effort yet you're still travelling at the same speed over ground.

Wastegates are fine...... 25/26 lbs of boost is what you should be seeing....You're just heavy with the tender....why come back with full water?