Flushing Lower Unit

[dblanton]

I am servicing my lower unit and the oil is extremely black, I was curious why the oil is so black, I bought the boat used a few months ago and I have only had it on the water 4 times. I drained the oil into a clear plastic container and drug a magnet through the used oil to check for steel grindings... everything ok there.

Can I run some kind of flushing fluid through the gear case to clean out the rest of the used oil before refilling with new oil ...if so what should I use?

 

[WillyBWright]

Re: Flushing Lower Unit

Flush it with any cheap oil you can find. Just don't put it under load if it isn't gearlube. Then drain and refill with marine gearlube.

Is this a new or used motor? Was the gearlube fresh when you got it? Blackness is caused by a lot of use, or a bearing that is getting too hot. Has the gearcase ever beeen rebuilt? Lack of metal filings is definately a good sign, so at least the gears are doing just fine.

 

[dblanton]

Re: Flushing Lower Unit

The moter is used, it's a 81 Evinrude, as far I as I know the lower unit has never been rebuilt or serviced.

 

[ezeke]

Re: Flushing Lower Unit

If the gearcase had milky oil in it to indicate that there has been a water leak or a lot of metal fragments, then service might be needed. The black oil does not usually indicate a need for any mechanical service, but rather, that the oil is worn out.

Using new TCW-3 gear oil will clean up any residue from the old oil. Run it a short while and change it again.

Be sure and put new seals on the vent screw and the fill screw when you put them back. Take the prop off and check for fishing line, grease the prop shaft and remount the propeller.

When you get to it, replace the whole water pump with a new BRP/OMC kit. It is good insurance.

Here is a link to lots of oil info:

http://www.outboardmotor.biz/oil/

I liked this thread:

http://www.outboardmotor.biz/t/011176.html