Oil dark in VP-SX drive Why and what to do?

[erie_guy]

Just pulled (for the season) my 1997 Chris Craft that has two 5.7 Gi Volvo Penta engines with SX drives. The Port engine overheated in August and I replaced water pump impellers in both engines (the metal drive cores had separated from the rubber impeller). The engines and drives performed well the remainder of the season.

When inspecting the drives I observed that the dipstick oil in the Port leg was slightly lower than the other drive and was significantly darker than the dipstick oil in the Starboard leg. Both SX legs have seen the same service and had an oil change two years ago. I do plan on changing drive oil in the spring.

Should I pull the port drive and get it serviced over the winter - to possibly determine the cause of the oil discoloration? Could this be related to the overheat condition that the engine suffered? It was over 300 deg F at the thermostat housing, according an IR sensor.

Or

Should I just change the oil as planned and see what happens next year? I could drain the legs now to see if water intrusion may be causing the discoloration My drives were stuck in the mud for several days during low water levels this year.

Thanks for any advice you may offer.

erie_guy
Port Clinton, OH

 

[83Evinrude]

Re: Oil dark in VP-SX drive Why and what to do?

I'm not sure our boats previous owner had ever changed the lower unit oil, and it was also pretty dark when I did this summer. I just changed it again as we prepare the boat for winter.

I think you should change the oil now. Check for water and debris when you drain the lower units, and if there is much of either then you probably should have them serviced. If there is water in either of them you risk freeze damage this winter.

Not sure on your 97 but Volvo calls for 75W-90 Synthetic in our 04, I used Mobil 1 from the local auto store.

 

[erie_guy]

Re: Oil dark in VP-SX drive Why and what to do?

I think your advice is right-on. I will drain them this weekend into an open pan so I can see any contamination.

 

[Don S]

Re: Oil dark in VP-SX drive Why and what to do?

The Volvo gear lube does get dark with heat. Since you did have an overheat, that may have been the cause.
If the gear lube was low, I would also pull the drive and check the bellows for oil. May have a leaky front seal on the drive.

 

[erie_guy]

Re: Oil dark in VP-SX drive Why and what to do?

Thanks Don,

I will pull the drive, after draining the oil, and look in the bellows for evidence of seal leakage. However, I don't see how an engine overheat could cause a temperature issue with the drive.

erie_guy

 

[Don S]

Re: Oil dark in VP-SX drive Why and what to do?

If your impeller came loose from the hub, then NO water was going throught the exhaust system, only hot exhaust gas. And it all goes through the outdrive and out through the prop. How long the impeller was damaged before complete failure, I don't know.
It was just a possibility, not a "It has to be this" type thing.

 

[erie_guy]

Re: Oil dark in VP-SX drive Why and what to do?

Thanks,
Now I understand how the outdrive would get hot enough to darken the oil. And yes, the impeller on one of the engines had spun for a while and melted the hub to impeller surface. The other was not bonded and could easily be popped out of the impeller material.

Both impellers were blue silicone "run-dry" impellers with a 2 year guarantee. I sent both back to the manufacturer with a letter - hoping this might make their engineering department take another look at the bonding process - glue? I probably won't use this supplier of impellers in the forseeable future. And yes, I replaced them with the more-traditional black rubber impellers.

Thanks again for your guidance.

erie_guy
Port Clinton, OH