Where is the oil level sensor and temp sensor on a 1990 Mercury 115 4 cyl, 2 stroke?

Question

My warning horn is giving a constant beep (overheat warning). I want to check the connections to the sensors, but I can't figure out where they are. I know they are on the starboard side of the engine, but I just can't figure it out. If you have a pic of where they are, it would really help.

Answer 1

To be sure you may need to purchase the manual, I had a similar problem on a Johnson/evenrude motor and found out it was a oiling problem.

But another suggestion is to enter into a forum at I Boats . com I did and I got a lot of good information from these fellas.

make sure to join the Mercury group

Using these experienced boaters to sound off and answer my questions I have become pretty proficient at my own motor in just 3 years

Answer 2

The temp sensor is found at the top of the engine right on the back, brown wire goes to it. You can start the engine and disconnect it to see if the alarm goes off. If it does with the engine cold, you can just replace the sensor ( DO NOT LEAVE IT UNPLUGGED!!!) The oil level sensor is found on the top of the engine oil reservior (port side of engine), two wires attached to it, looks like a cap. Look at the tank on the engine. If it is low, you may have a transfer pump problem. If you have changed brands of oil, the float could be stuck on the sensor. Remove the cap, turn it over and see if the alarm goes off when you start the engine. A slight tap may help. If it does, I recommend you take the tank off and drain the oil. Often we find a gel like substance in the bottom of the tank caused by dissimilar oil composition causing gelling. Clean the tank with a spray of carb cleaner, dry it out completely, refill and your done. If these fixes don't do the trick, take it to a dealer. You don't want to blow it up.

Answer 3

Is water coming out of the dischage tube ? If not you most likely have a obstruction.( grass , dirt dobber, spider) inside the tube. Find the rubber tube that comes off the back of the engine and blow it out.

Answer 4

you probably have a bad watepump or an obstruction in the water intake, waterpump impellers should be replaced every 4 or 5 years due to the rubber gets hard and brittle and crumbles away over time.