DF50 2004 Drive shaft scoring

[RayBersch]

Changing impeller (first in many years) and noticed that the drive shaft is rather scored where it passes through a grommet at the top of the water pump housing. I will replace the grommet but I'm not sure how well it will seal with this scoring of shaft. Is this something unusual that needs replacing or standard for a motor this age? Should I try to clean it up? (The old impeller looked in good shape with little wear noticeable.)

This motor has about 210 hours and I just installed an engine interface cable leading to a Lowrance HDS7 Touch. I have owned the motor for 9 years and have never had an overheat but with the new engine information I noticed that at WOT (6,200 rpm) the temp is 200°, at 4,000 rpm the temp is about 155° and at 2,000 rpm - which is where this motor lives most of the time) it is 134°. The service manual notes that the overheat alarm kicks in at (a surprising) 250° while the thermostat opens between 136° to 144°. So, do the numbers I am experiencing seem normal?

[RayBersch]

OK, I solved the issue today. The drive shaft is not scored, its actually machined to a smaller diameter than the rest of the shaft as it passes through the water pump housing and it cleaned up nicely with some 600 grit abrasive - I can just picture the two Japanese engineers - "Hey, your shaft is too large for the water pump housing I designed." "No, your water pump housing is too small for the shaft I designed." And so it goes with engineers.

Also, with the new impeller and a double checked thermostat, I am still seeing 188° water temp at WOT - I think that is high - but I usually hit WOT only twice a year on trips to or from the launch ramp so I'll leave well enough alone.

Ray

[Moonlighter]

We work in metric degrees C here in Australia (us and the rest of the world apart from the US, Liberia and Burma ) and your 188F converts to 86.6C, which is close to what I get running at high revs on my DF115. Maybe a touch higher, but not much.

So thats pretty well normal temps in temperate waters run at high revs.

Some debate about what temp source that is coming from on the motors as there can be a couple of different sensors depending in the model.

[RayBersch]

We work in metric degrees C here in Australia (us and the rest of the world apart from the US, Liberia and Burma )

Yes, and so does the repair manual - I had to convert from C in some cases where the manual does not provide conversions. I wish the US had successfully converted to metrics because it is much easier to use. But thanks for the info. My experience with the Yamaha F150 on my Skeeter is about 57.2°C at WOT so I found the Suzuki numbers high - I will rest easy with your information, thanks.