Lower drive discoloration
 

So finally got out Sunday after rebuilding starboard drive. Pulled boat out and the port lower (IMCO shorty) looks "rosey" colored. Fluid is full, not sure what would cause this. Ran fine but looks like that lower got really hot. When the Bravo Shop here at the lake rebuilt my starboard drive due to the lower destroying itself (rebuilt last year) was because it wasn't set up right. I'm sure this lower will need something this winter but just curious if anyone has seen this on their casing before. Thanks.

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The round spots on the drive have always been there, it's just now it has turned a rosey color rather than silver.

That is about to be a bearing failure which will twist off the vertical shaft. Time for a rebuild.

How do you figure that? Those are welded in those spots right from IMCO

427,
What does the SB lower look like?

Starboard lower
 

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I was looking at the heat bloom near the rear bearing. Was not aware that it is normal for imco. Saw something similar on a bravo right before it locked up and twisted the shaft off.

My IMCO SCX's recently developed a similar color but only on one side of each drive. I thought back to the last time I cleaned them and I'm almost certain the sides that have the color on are the ones I used still wool on.

Did you clean the colored drive with something different than the non-colored drive?

No, I've never cleaned them. The starboard was just rebuilt. I called the Bravo Shop here at LOTO and they said the color really doesn't mean anything. Aluminum housings color differently for different reasons. They said clean it with some aluminum cleaner if I don't like the looks, but it doesn't necessarily mean there is anything wrong. I'll pull the prop and drain a little fluid and see if there are any signs, if not, RTF. Run to failure.

Called IMCO just to verify and they confirmed what the Bravo Shop told you. They said lots of things can cause this type of discoloration on the lower unit, so nothing to be concerned about. They didn't say ignore all discolorations, but this color can be called by lots of things, but not a heat issue.......knock on wood!!!