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Thread: Suggestions for 21' NR Commander Repower?

  1. #1

    Default Suggestions for 21' NR Commander Repower?

    Just learned my 2006 North River Commander Marine Power Vortec 350 with less than 50 hours has a bunch of metal in the oil pan. I noticed a rattle and oil in the bilge on this years moose hunt. I also had to run it at 3800 rpm to keep on step on the Yukon. If I slowed down to 3600 rpm the boat would start dropping and eventually come off step. I had 4 hunters on board with a light camp and no moose. The boat always did want more rpms than it should. Brand new it needed 3400 rpm. I've taken very good care of the motor and boat. I hit my first gravel bar this year on the Talkeetna. The noise and oil started before that. I took the boat to the shop to have them locate the oil leak. I assumed the impeller needed some work and maybe the bearing was the cause of the rattle. Never expected to hear the motor is coming apart. The boat is still like new.

    I need to repower. My options are to rebuild my motor or get a new motor. If I have to repower I would like to get a little more horse power if possible but I can't afford to get crazy. My current setup is port fuel injected and the pump is a hamilton 212. I don't know what impeller. It's all stock.

    Any suggestions?

  2. #2
    Member akriverrat's Avatar
    Join Date
    Apr 2007
    Peters Creek, Alaska, United States, United States


    if you go more power you will have to put in a bigger impellar to match. next size up would be the 454 with the 3.4 turbo impellar. not sure what the performance is or if its worth it. my old northriver did fine with the 350 and 3.2 turbo. on step quick and 50MPH top speed. cruised at 3400 but any lower yea it fell off step after a while. sucks you are having motor problems, wayy too early for that. i was happy with my setup and everythign was strong when i sold it.

  3. #3


    One time with 12 hours on the boat I hit 44 mph top speed with 1/2 tank, me and one passenger on a glass surface at Skilac. I will likely rebuild or get a long block and have the impeller reworked if needed. I can't afford to change everything.

  4. #4
    Member chriso's Avatar
    Join Date
    May 2006
    Los Anchorage

    Default You need to determine which impellor you have...

    You should be able to shine a flashlight up in the tailcone and see the pitch stamped on it near the hub... if you have a 2.4 then those kind of rpms would make sense. If you have a 3.4 then it sounds worn, by quite a bit as far as that goes. Its a bummer about the shavings, the 350 vortec is a great motor.

    Bumping the bottom of the boat, while it could tweak things enough to make some noise develop so far as alignment goes, would be tough to imagine it did anything to "break" the motor if you know what I mean. But then, you said the rattle was developing earlier anyway... I have hit hard enough to crack the cast aluminum oilpans these KEM and Marine Power motors come with, if the bottom flexed enough for a bolt head on your jet intake to touch that oil pan you could have something like that wrong... and of course, if you then had it run low on oil you could have caused the issues with the motor. But, unless this was the case, I'd tend to think the metal shavings in the oil are an unrelated issue to the noise developement since the bump.

    Hopefully the leak is more like a hose fitting or adapter that goe tweaked instead of the oil pan. Usually if you hit hard enough to crack the pan, you will have cracked the cast aluminum intake North River built with as well. (I sure hope not) are you getting more water than originally in the bilge?

    I'd flush the motor really well and get new, clean oil in it and run it some yet this fall to see if you can determine where the noise is coming from.... you dont want to wait till spring to try deal with this, and you dont want to just rip things apart more than necessary this winter and end up throwing more money at it than necessary due to lack of time to adequately troubleshoot the thing. I'm betting the noise has to do with pump alignment from the motor shifting, the impellor is a 2.4, an oil hose adapter fitting is bent or cracked and the metal shavings once flushed out and clean oil in the motor, will turn out to be a non-issue (hows that for some optimism)

    By the way, Alvin at Artistic Aluminum Fabricators in Wasilla is the "best" Hamilton guy in Alaska (IMHO) he's saved me tons of time and money with his knowledge. I'd have him re-pitch that impellor to a 2.8 if I were you, I think a 3.4 is too big for the 350 Vortec, and a 2.4 is too small. (again, IMHO)

    I guess all this speculation is based on you not already having determined the motor has serious problems.

    Good luck, Chris

  5. #5


    I'll find out about the pitch today. Forgot to say that we found the oil leak coming from the front crank seal. The oil leak and the noise started before the bump. I just mentioned the bump to illustrate that I haven't abused the boat. It was my first encounter with the bottom. I got out and rocked the boat off. It put a finger size dent in front of the transom on the starboard side in front of the sending units. The bottom in front and behind the grate is slightly scratched. No damage. Thanks for the input.

  6. #6
    Member Sobie2's Avatar
    Join Date
    Jul 2006


    Check the impeller, maybe if you are lucky shim it. I would not repower with a big block... you are talking 10k for just a long block. I'd get another 350 if you even need one, they can be had for $3500 or so. Check out

    But before any of that since the boat has only 50 hrs metal in the bildge could have been from the buidling of the boat that rattled its way from the bow or other places that couldn't be cleaned before delivery... maybe a dropped nut also or something. Do a compression check. 50 hrs on a bad river and sucking rocks can affect a jet.


  7. #7
    New member
    Join Date
    Apr 2006

    Default check out

    S&S rebuilt engines Or one of there partners my motor came from washington.
    I got a longblock Marinized 460 delivered to juneau for about 2100 And thats including paying a core charge. And came with a one year warranty. This was 2 years ago but I think they are still the same price. I got 100 hours on it so far and no problems. And I have run the guts out of it a couple times.

  8. #8
    Member Dupont Spinner's Avatar
    Join Date
    Jun 2007


    If having to replace do the 6 liter or do a big cube small block like a 406 or a 427.

  9. #9
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    Nov 2009


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