1975 Johnson 115hp keeps locking up

[veno1128]

We are two college kids here with limited knowledge of outboards. We were going along at 3/4 throttle when the engine RPM started to slowly drop. We backed off the throttle and the engine locked up (flywheel wont move). The starter managed to turn over the engine and get it started, but immediately locked up again. This happened one more time and then the flywheel wouldnt budge. After trying to jar the flywheel free by hand for 5 hours, the starter managed to break it free and get it started enough to get us back at 2 mph, sounding horrible. All fluids are fine, oil is fine. What can we do??

 

[steelespike]

Re: 1975 Johnson 115hp keeps locking up

One of 2 things Not enough oil in gas or your water pump or thermostat failed.<br /> Seized motor is a very serious condition.<br /> Pull spark plugs and peek in with flashlight.<br /> Look for scoring on cylinder walls.While your discription sounding horrible is a little vague<br />it sounds like you have some serious internal damage to the motor.<br /> Doesnt look good.

 

[Fair Boater]

Re: 1975 Johnson 115hp keeps locking up

Try this link from troubles I had with a lower unit...<br /><br />My 73 Johnson 115 was binding when starting and it turned out to be the lower unit. <br /><br />I'll describe how to check for lube fluid in the lower unit:<br /><br />You'll have to trailer or boat-lift the boat to get the whole motor out of the water as the check is done at the bottom of the motor, with the motor upright.<br /><br />There are two plugs for the lower unit: one about 3/4 of the way down on the right side of the motor(lube level check plug), and another way down at the bottom right side (lube fill plug). Check for lube fluid by pulling out the plug at the bottom (fill plug), (flat blade screwdriver needed). If you take it out and a ton of water flows out, you have no lube in the lower unit (BAD!).<br /><br />If a thick fluid flows slowly out of the hole, you are seeing lube fluid (GOOD!). <br /><br />The fill plug has a magnet attached to it to catch any metal shavings. Cover the hole and check the plug for metal. I had tons from a lower unit destroyed by loss of lube through a hole worn in the lower unit housing.<br /><br />If you find decent looking fluid in the bottom plug, replace the plug and pull out the upper one. You should see the thick lube fluid in it, too. If not, use a paper clip to check how far down the fluid level is.<br /><br />Hopefully this is some help for you!<br /><br />I'd recommend finding a manual for the motor as soon as possible, especially if you are interested in doing at least some work your self. It's been a lifesaver for me.