1981 50 horse evinrude had all water in lower unit?

All water and a touch of creamy oil. Came back off Bago  The engine suddenly bogs down and starts making a terrible sound. Like something grinding… metal on metal?? Then I put my Minn kota down to bring me in and it would keep pulsating every 3 seconds?? Ideas please I just bought this boat. UURRRGGGG. Stay on top! Wj

That top hole should be the gear case fill hole. Gear case fill/drain bolts will most likely have a slotted head, not philips. If you need the schematics, I usually go to the crowleymarine website. It's free to look up and the schematics will help a lot. Water is probably getting through the prop shaft seals like others have stated, there's usually 2. The most common and fastest way they get destroyed is when fishing line gets caught between the prop and gear case housing. As the prop shaft spins, the fishing line just eats up the lips of the seals and let's water in and oil out.

Not trying to be a jerk....but I am hoping you keep on the path you are to try and fix it easily.  That way in the future I can be confident in my decisions to tear things down or replace them.....whether it is a motor with issues or a transmission that is slipping...etc..

So now I did it.. I took three screws out of the lower unit. One was the top Philips  head I surmise was holding the shifting rod. The new Philips head screw now goes all the way into the hole and doesn't catch just spins. With the issues already that I've told you about what are my options please before I stop fishing....

Hi all  so I put the magnet screws in and have changed lower unit oil at least three times since last I posted. Still have metal shavings on the screws. Looks like the top screw has more metal than bottom screw. Still the motor works. Is there a way to cut down on the gear oil cost and either flush lower unit ?? Ive changed oil after each excurtion. Stay on top! Wj

WJ- Sounds like you have her going in the right direction. Hope she runs smooth for you.

Update... The bottom lower unit screw had no washer on it. I put new oil in and just got off the water . Went in reverse no noise went out into lake fast no noise! Took prop off trolling motor and stripped a bunch of line off. The trolling motor works now! Im going to change oil again and put in a magnetic screw.

Drain the lower unit and put the oil through a coffee filter or even a paper towel.  If you see metal shavings it’s all bad...

You mentioned hearing a metal on metal grinding noise, I’m guessing your lower unit is toast. 

The cheapest route is to find a motor with a blown power head, and change out the lower unit.

Thanks guys! Where should I start? I'm going to fix it myself. Do I put oil in and try it out or start by taking it apart?

Not uncommon for older motor to have a little water mixed in, when does, time to change the prop seal, fairly easy to do, and may have to make your own tool threads to put bearing housing back in.  I did that to my 60 couple of years ago.  You may want to check the shift linkage height, just pull lower unit, ensure in neutral, look up in manual says what measurement is.  Use a yard stick, tape a drill bit on it, works for measuring.  If off, will get some grinding.   Just purchased larger boat, so, have mine on market, and I have extra lower unit with it just in case, someone tossed a 70, so, took some parts off of it to convert to non VRO, and kept it.   This new Yamaha, doubt if I can do much work on it except for changing impeller,  etc on it.  All electronic stuff.  

If you heard metal grinding, your lower unit is shot...

You likely have a bad seal which allowed water into your lower unit.  

Your best bet is to buy a new / refurbished lower unit.  

A second option would be to find a blown motor, you can get them for pretty much nothing, and just swap out the lower unit.  

When you are looking at purchasing a new / used motor, always remove the lower unit plug to see what comes out.  Some folks will sell you their problems without regret.

Also, a lake test is an absolute must.  A motor with lower unit issues will run just fine on the muffs, but can't handle the torque required to get the boat on plane. 

You probably blew a seal on the lower unit which allowed oil to drain out and water to get in and created the sludge you see. Hopefully you shut the motor down before it got too bad.

I had the same issue a couple weeks ago and luckily noticed an oil slick in the water before I started the motor. I put it back on the trailer to discover the gray sludge. 

I made the mistake of not checking the lower unit of a motor I bought one time. Never again! I was on the lake when the shaft completely snapped in half - there wasn't a single drop of oil left! Always check the motor over throroghly, it's one of the most expensive parts of the investment! And of there's a trolling motor check thru that too! Looks like you'll have repairs to do. Mine was a 25 hp and instead of spending 400 bucks to fix the motor i sold it for parts instead and eventually I sold the boat as well!