The 340 Learning Curve.....HELP

[Scottzzzy]

First of many questions as I am into my first season with my 2002 340. I have 8.1 Horizons that are closed water cooled. The running temps have been dead on 170 on both engines with oil pressure at idle and at average running rpms about 40-45 psi. Just this last 2 times out I have noticed the port engine running a little hotter and the oil pressure creeping up a bit on the port side.

just yesterday I am coming off plane the temp gets even higher on port engine only and the oil pressure drops to 30 on both when I throttle back fully.

I know I am due for a full fluid service, but can just the viscosity of used oil make this much difference?

i am looking for some serive ideas of items to check.

 

[AAK]

Without getting into a thousand things that could cause the engine temp to rise; when is the last time you had your raw water pumps rebuilt or replaced? That usually is one of the first things to cause the engine temperature to start to rise. Another obvious thing to check is to see if you pulled something in the sea water strainer.

 

[Hampton]

Things basically sound normal. I never come off plane aggressively. I try to throttle back to 2000 RPM, let the wave lift the stern, then throttle back NO lower than 1000 for a minute or two. The engines have full running heat built up from TONS of internal explosions, then are instantly subjected to idle cooling when you come off plane - try to let them down slowly.

New impellers could help, but maybe not.

Oil viscosity shouldn't make too much difference. When the engine is cool, the oil is thicker. When you start up, you'll have higher pressure than at idle after coming off plane. The max pressure is regulated by pressure relief valves, I think.

 

[carterchapman]

Scott,

My oil pressures run 50 when cold at idle and 35 when hot at idle. I'm using Mercruiser Full Synthetic 25-40 weight.

I forgot how many hours you have, but do you know when the impellers were last changed?