Here's a dumb question....

[DjKoKo]

I know this maybe dumb BUT I'm sure other inquiring minds besides mine would like to know. What will the lower unit do on the water if the gear oil is old? Slip? Not get up to speed? run at higher RPM on the Motor? Or just run normal?? Just wanting to know.

Johnson J150STLCOS

 

[Cofe]

Re: Here's a dumb question....

As long as there is no water in the oil or metal fragments the oil would last a long time. Unfortunately water condensation happens in lower units due to temperature swings. Oil should be changed before season, and when put up for winter. Water in the lower unit will cause rust, and things start coming apart. Hope this answers your question.

 

[e10]

Re: Here's a dumb question....

Short term nothing will happen, long term gears and bearings may wear prematurely.

 

[emdsapmgr]

Re: Here's a dumb question....

As long as the gearcase is full of oil, you are probably ok. If the case gets low on oil for any reason, the remaining oil can get overheated and turn black. At that point, you will want to change it immediately.

 

[5150abf]

Re: Here's a dumb question....

Being 80/90 weight oil it will last a long long time and no it can't make the engine run badly or slip given it is just old with no water in it, that would be a different problem.

You should change the lower oil at least once a year, preferably in the fall as part of you winterization, though since that is the only way to tell if a seal has gone bad and I check mine periodically by cracking the bottom plug after the engine has sat for a day or two, if there is water it will come out first.

So what is this boat doing that prompted this question?

 

[Silvertip]

Re: Here's a dumb question....

When was the last time you changed gear oil in the differential of your rear wheel drive car, truck or SUV? 90% of those vehicles don't have that fluid changed between the time it leaves the factory and when it ends up in a scrap yard. Unless there is a problem in the lower unit it will last indefinitely but it may turn to tar if the engine sits unused for decades.

 

[DjKoKo]

Re: Here's a dumb question....

Winterization not a problem here in South Florida. I have a used motor that I have put a lot of time and effort into. Replaced Water pump, Primer bulb, Drained gas tank, Replaced Water Intake screen, 1 Power Pack, Fuel (VRO) Pump, Clean out and changed water jackets, Plugs, Wires & Rebuilt carbs. Only 2 things I didn't do was Thermostats (which there wasn't any) and didn't change gear oil. I ran it yesterday and it ran fine EXCEPT it made like a loader low pitch roar at higher speeds which I have never heard before on motors that size (150). It also seemed like the when it was planed out, it sounded like the prop was out of the water and spinning free until I back it down a tad. didn't know if either of the 2 things I didn't do would be an effect on it. Gear oil not being changed was my big one.

 

[boobie]

Re: Here's a dumb question....

You may have a prop hub that is starting to slip.

 

[DjKoKo]

Re: Here's a dumb question....

Well, while I had it up on the trailer and it's been sitting for 3 days, I thought I'd try the "put it in gear and turn the prop by hand the opposite way" method of testing it. Results...it turned not real easy but it did turn and I could hear a squishy noise coming from inside the prop when I was turning it. Prop Hub bad???

 

[cr2k]

Re: Here's a dumb question....

Most likely

But please don't listen to anyone telling you you never need to change your lower unit oil. Car differentials are made of cast iron not aluminum.
Any amount of moisture can corrode the aluminum and rust your bearings and races.

 

[DjKoKo]

Re: Here's a dumb question....

just talk to the Evinrude shop and they will do the rehubbing for $100 or Less. Not too bad. as far as the gear oil goes YES I am going to change it out as well but I can do that myself. I wish I could do the rehubbing too.