Re: Routine thermostat replacement, 90HP Johnson
I have strange story about a 90HP Johnson, 2000 year model that i believe is overheating.
Motor was running fine until my wife loaded our pontoon boat on the trailer last week. (It could have happened to me). I pulled the boat out of the water and found a black tube wrapped around the prop! At first glance, I thought we had inadvertently picked up some trash that got wound up around the prop. fI started looking closer and then realized it was my black hose! Was it the gas or the oil line? I soon discovered that it was my oil line from the oil reservoir, about 12 feet of hose, to the outboard motor. Well, I was in disbelief but strange things happen when i operate marine equipment. The oil line had gotten loose and fell down in the area in front of the motor between the 2 pontoons. Apparently, the force of the water on the hose pushed it out and under the lower unit and the rest...well,,,, the hose was wound up on the prop like a spool of fishing line on a reel! I cut the oil line loose and came back the next weekend with a new hose. I replaced the hose and started the engine...this is when the fun began. My mechanic told me, as a safety measure, to mix oil in the gas while running the engine after replacing the oil line to prevent the engine from running without lubrication. Good thing i did that because the No Oil Alarm on the dash board started going off and the light stayed on! It gets better...... thinking i had fixed the problem by replacing the oil line i try the boat and it runs but starts cutting out. I ran it at idle and WOT. It ran ok for awhile but every time i killed the engine and restarted the alarm routine and light would stay on for the duration of the run. It would run wide open ok but at speeds in between it started cutting out. I ran the engine with the muffs after that and the alarm kept doing the same thing. Now, all this time i'm thinking it's not getting oil from the reservoir but remember i added oil to the gas so...there must be something else going on.
After messing with the engine on muffs i discover that 2 of the cylinders are hot to the touch while the other 2 cylinders are just warm to touch. This was determined by running the motor on muffs at idle to fast idle. The no oil alarm light is lighting up while i hear a long steady alarm. The alarm starts after about a minute of running and the alarm sound stops after a one minute or so. The engine seems to run fine at idle. From what i've been reading i believe the long sounding steady alarm means the engine is overheating. Do I have that correct? now i'm thinking...ok...maybe the engine is getting plenty of oil but the thermostat for the left bank cylinders needs replacing. Is that a logical conclusion? I'm going to try and find out what thermostat fits my engine and replace. I am now convinced that the NO OIL ALARM indicates no oil OR overheating. Not sure how the thing is wired but that's the conclusion i've come to at this point.
Is there something else i should do here ??
