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What may cause a Mercruiser D183 RPM problems (when in free it reaches max rpm - when running NOT)

mawrick

New member
My brother have a Mercruiser D183 AC (I think 1994 model) (5 cylinger diesel turbo).

The engine doesn't seem to be able to reach full speed, and not full RPM when it's running the boat.

If the gear is put into "free" it will actually rev up to max, but when engaged can't reach max rpm.

I think it will reache around 15-1800 rpm (roughly) - maybe a bit more.


Any tips on what might cause such a behaviour?.
 
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My usual question... did it always do this or did it run OK at one time?
Given a complete lack of information on the engine's history, one of my first SWAGs would be... IS this the factory original prop, or did someone try to get more speed out of the boat with a prop pitch change?
 
As far as I know the boat did run fine one day and a few days later (after not beiing used) it didn't run properly again......at least that what I'v been told - however there have been some really weired things done to the wiring - like cutting the sockets for relays etc - but everything seem to be hooked up properly though......not that I think that can be related to this issue as I presume there isn't much electronic managment on this engine).

The prop seem to be of original . I had a look on it, and I see some small damages (but nothing major as far as I can judge) to one of the props (it'ss a bravo three or what it's called).......

All the filters have been changed after the problem occured....:(


I have been told they had seen some leak from the gasket that sits on the side of the turbo - might a leak here cause such problems...?


Also the turbo seem to rotate just fine, and there isn't much movement on the bearings either so can't see that it's the turbo itself personally but .....
 
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