low engine revs

[belly1958]

Hi I have a 2009 maxum 2500SE with a cummings 200hp diesel on a mercruiser bravo 3 leg, the boat is new to me so i'm slowly finding out things that dont seam right to me.
firstly the engine only has 100hrs on it but does not rev more than 2800rpm in neutral or in gear giving a top speed of 32mph, am I correct in thinking it should rev at 3800 and if so has anyone got any ideas as to what to look for to solve this problem.
Also it seams to take a long while for the engine to warm up and then only reaching about 115'f then when underway at 6mph it go's to about 135'f then when at full throttle it reads 175'f returning to 135'f when slowed down to 6mph.
Any thoughts on these two matters would be much appreciated, thanks, peter.

[shrew]

Welcome Aboard belly1958!!!!

That model should be the Cummins-Mercruiser "4.2 MS 200".

Make: Mercruiser-Cummins
Model: 4.2 MS 200
kW: 147
BHP: 198
MHP: 200
RPM: 3600
Rating: High Output


If you can only get to 2800rpm, that sounds like a problem. Id' try checking to make sure it's not a cable or linkage problem. If that is not the problem, then I'd be bringing in a Merc Diesel mechanic to take a look at it.