76 200hp evinrude thermostat

My alarm kept going off on my 200hp evinrude,noticed that prior owner took thermostat out what would be the reasoning for this?Also would it cause alarm to keep going off?Motor runs great other than alarm going off.Any input would be greatly appreciated,thanks

Re: 76 200hp evinrude thermostat

Have you replaced the impeller? Does the alarm go off when idling or when running on plane? First, verify the head overheat warning by borrowing/renting a laser temp gun. Each head should be 145-155 at idle when warmed up. The overheat should go off when the engine reaches 212. These engines need to be run with thermostats. Missing stats cause the engine to run cool, which hurts fuel economy and promotes carbon accumulation around the rings as well as excess smoke out of the exhaust. Having said that, it is unlikely that the missing stats are the cause of the overheat. Prior owner probably had some other overheat issue and took the stats out thinking that would solve the issue. I'd pull both stat housings apart and replace the stats and check the functioning of the pressure relief valves. If it still overheats, I'd pull the head covers and see if the heads have debris in them, sand, weeds, etc. If you find debris, you need to pull the heads and have a look for debris in the powerhead cooling passages. Possible the water diverters in the block are detriorated or out of position-that will cause an overheat.

Re: 76 200hp evinrude thermostat

Thanks for the info,im changing stats tomorrow,one thing i would like to add is the alarm doesnt go off everytime im out on the lake ,sometimes it wont go off at all for a couple trips out on the lake ,then when it does go off while running at a crusing speed it will also just shut off and wont come back on. I can troll around at a low speed for as long as i want and the alarm wont come on at all,Impeller was changed recently pumps great.i will do as you said and keep you informed,thanks

Re: 76 200hp evinrude thermostat

check for a cracked insulation on the tensor wire, could be shorting out.

Re: 76 200hp evinrude thermostat

Tas has a good comment-You need to determine if it is really overheating or a faulty horn switch signal.

Re: 76 200hp evinrude thermostat

Installed new stats solved the alarm problem does not come on now,i noticed there was a small hose about 3ft long just laying inside the cover, its connected to the outter exhaust cover by a brass fitting towards the top of it ,i never noticed it before my manual doesnt show where it is supposed to go,its like a small vacum line one end connected to the exhaust cover between heads and it was just coiled up laying on bottom of motor if you did not look you would not notice it wasnt hooked up any ideas where its supposed to go?

Re: 76 200hp evinrude thermostat

Good that you got your overheat problem fixed. When running, does water come out of the fitting? OMC began installing overboard (telltale) indicators in the 1978 model year. These were plumbed into the lower exhaust cover. In later years it was moved toward the top of the cover. The prior owner may have tapped the exhaust cover and installed a hose barb to drive a water pressure gauge in the dash, a nice feature on this high performance engine.

Re: 76 200hp evinrude thermostat

Nothing comes out of the line while running,it doesnt seem to effect the way it runs,i put this motor on my 19ft open bow alum sylvan boat last year,after a lot of fine tuning last season and this season i believe its finally going to be ok after fixing thermostat and solve the buzzer problem the other day,i figured i would take a shot and open it up on the lake,she planes out about 25mph and max out at approx 46mph thought that was pretty good for a big alum boat,Although was hoping for a little more speed like 50-55