I have a 84 50 hp merc im taking out of moth balls to run on a 16ft flat but the water out the piss hole seems really hot to me. is this normal? what could be causing this problem i changed the impeller and the gaskets with it. i mean its pumping water but its just hot i dont see a thermostat and the schematic sheet doesnt show one either also the end piece on the water line is missing so its just a straight hose the water is coming out of could this have any thing to do with it? any help would be appreciated

As long as it's pissin, don't worry bout it.

i'd say its normal... the water that comes out of my 86 suzuki 75 is hot

its just way hotter than my other outboard if i had to guess its about the same temp as out of a hot water heater it was my dads motor but he cant remember if it was like that before or not i just dont wanna burn it up for no reason if its something that could be fixed

as long as it has a good steady stream i'd say run it

With the motor idling, my Mercury Mechanic always caught some of the discharge water in his hand. If you could hold it for a second without it scalding you, it is ok. You can also pull the cover off and be able to lightly place your hand on the head. It should be pretty damned hot, but it should not burn you if you just touch it momentarily. If your hand sticks, it's too hot! Watch out for the flywheel.

Might be the thermostat stuck or unstructing the water flow. i know on my 40 merc i had i pulled the thermostat cause it kept getting cloged with mud or duck weed. that migh be an idea.

If it is a 4 cylinder with the wrap around metal cowlings, then yes it does not have a thermostat.

Also (if that is the model motor you have), the water coming out of the tell tale hose should be pretty close in temp to the water it is running in. The tell tale hose gets water before it completly cycles thru the block and gets the same temp as the block (unlike most of the new outboards where it hooks to the thermostat cover or exhaust plate). So if the water is more than about 90 degrees you either have a bad water pump, or a blockage in the block not allowing water to cool it.


If I were you, i would install a water temp gauge on it and go run it. If you dont want to drop the $$ on a gauge, the outside of that block should be very cool to the touch. That is really the only way that you can determine if you have a problem.

There is one other possibility. I havent seen very many of them, but that motor has a design flaw where water doesnt completly drain out of the exhaust plate (the one that the block sits on top of) and it will rot out causing exaust to blow into water chamber which will cause the motor overheat too.

By any chance, do you see any air coming out out of the tattle tale hose (especially when you throttle it up), or just a solid stream of water?

that would have been a good bit of info to know from the start, but yes you are correct in that a piece could be causing a restriction somewhere.

only word of caution, on a motor that old be very careful in removing the bolts from the water jackets as you may find one or 20 that are corroded/frozen in the block, especially the ones closest to the bottom.

it should come apart easy it was all taken down my grandpaw had got some work done to the carbs and had everything else checked out but decided not to use it so it got picked back up in the garage till now but thanks for the help ill let you know what happens

also a quick check is to get a air compressor and stick the hose in the tattle tale and blast some air in there while its got left over water in it. that will force any trash out backwards usually and fix a clog. that what i did numerous times and it worked. might try that before you break it down. could save ya time.

The water temp should be hot. If it was cold is when you should worry, which would indicated the water was not getting through the jackets to cool the cylinder. As long as your block can be touched while running, the cooling system is doing exactly what it is supposed to.

it had some old impeller in it now its running cooler than before its just warm water like its suppose to be thanks everyone for the input

How did you get the old impeller piece out? Did ya pull it apart or blow it out?

took the foot off and filled the engine with water and blew air in the pee hole and they also had some in the foot below the pump that came out when i took the pump off and turned it over

now the only problem i got is i have a 20 inch transom with a short shaft motor so im gonna have to cut the transom or put the yamaha 40 i bought with the boat with a console back on but i rather the merc with the tiller handle i aint decided yet

tiller the 40

Two friends of mines changed the impeller on a 60Hp Yamaha last nite .... only three ears was left on the impeller .... reckon where the rest is ??

Re: 1984 MERC 50HP PISSING HOT WATER?
quackconsumer wrote:
jp0242 wrote:
its just way hotter than my other outboard if i had to guess its about the same temp as out of a hot water heater it was my dads motor but he cant remember if it was like that before or not i just dont wanna burn it up for no reason if its something that could be fixed

"Hot Water Heater" ????? Why would you heat hot water? Do you mean "Cold Water Heater" or "Water Heater" ?


Actually you would heat hot water for many reasons. in a lot of applications several heaters are needed to reach certain operational temperatures. There are such thongs as Hot water heaters, just not in your house lol

It still running a hot pops and me took the exhaust plate off today and there was some clogs on some of the port holes going to the cylinders so now just waiting on the new gaskets to come in to put her back together and see what i got

well put it back together and just the top cylinder is hot the lower three are good so gonna take the block head cover plate off and see if we can find any clogs there

fyi, that is a one piece block and doesnt have a cylinder head.............but yes the rear water jacket should be removed and inspected judging from what you found elsewhere.

no clogs behind back inspection plate so idk what else could be causing just top cylinder to be hot any ideas would be appreciated thanks

I always thought that if I could hang on to the wire without it burning my hand to bad when I was poking it in that hole to try to unclog it that it was not to hot.

its a lot better than it was before i cleaned out the water housing it just seems pretty hot at idol rev up its not to bad maybe its suppose to be like that its as old as me so im not sure and my pops cant remember how hot it use to be lol

its fine

i know someone who has two he will sell for cheap both long shafts

hey garrett i sent you a pm last week did you get it