Modern Common Rail Diesels

[Rockjumper]

On startup and shutdown today I noticed the slightest hint of diesel sheen on the water. Is that normal or, sign of an injector or other problem?

Most of my previous boat experience has been with outboards or old diesels on old sailboats where a bit of sheen was normal.

 

[S. Todd]

Based on our experience over the last seven seasons with both a Volvo D-3 and D-4, I would say it is not normal. If you noticed it at both start up and shut down, assuming that was done in the same place, I would question whether there was another source for the sheen that you did not notice at first. The actual source can be a good distance away.

 

[scross]

We were getting a very small sheen around the stern two years ago. Turned out to be a leak in the trim tab piston seals. I rebuilt the piston with new seals soon after.
It can be difficult to identify the source of a small sheen - especially if it’s intermittent. In our case it was found by noticing a slow drop in the trim tab fluid reservoir.

 

[CaspersCruiser]

I am another Ranger Tug owner that has had a sheen at the stern and thought it was coming from the exhaust. I posted about my suspicions here on Tugnuts and Andrew Custis, bless his pea picking heart, replied and suggested it was likely a trim tab actuator leak.

I went to the boat and, without starting the engine, actuated the trim tabs one at a time. Sure enough, a sheen appeared after moving the port tab. I ended up replacing the actuator after a reseal failed to stop the leak.

If you try this troubleshooting method, keep in mind that the right tab switch actuates the port tab and the left tab switch actuates the starboard tab.