1975 85 hp johnson waterpump burndown

[steely51]

I have just burnt up two pump kits on this 1975 85 hp . first on earmuffs then in a barrell.. my seloc manual doesn't show the water circuit or a view of the inside of the gearcase below the water pump it doesn' even use a two tube pump for the illustrations. I will order the parts for the thermostat and checkvalve today and a new pump kit but I would like to figure why this is happening. there is one heck of a void below the pump and i understand that it will take a lot of water to fill it. when I got the motor it was loaded up with a lot of mud daubber nests, I blew them out with air and water . there is a little opening behind and a little lower on the left side of the pump housing and it looks as though it may haave had a welch plug in it, which I may have blown away. its location leads me to think this may have been the case, for it looks like it would create a more positive suction from the screened water pick-up ports to the pump . this morning i read a lot of good info from previous posts concerning similar engines one being a 75 115 where a new pump fried, but the author didn't say if it was resolved. can someone enlighten me on the water passage from the pick to the pump,and confirm or deny the existence of a welch plug. Are oem manuals available for this engine? Thanks...... Roger

 

[wilde1j]

Re: 1975 85 hp johnson waterpump burndown

Never seen a welch plug in a lower unit. Water typically comes in thru a screened side opening to the suction side of the pump. During normal operation, water is present fairly high into the midsection.

Shop manual: outboardbooks.com or ebay

About the only thing that will fry a water pump is too little water or not deep enough.

 

[cougar1985]

Re: 1975 85 hp johnson waterpump burndown

sure were not talking about the water pickup tube hole?directly below the pump you should have a plate which the impeller sits on .

 

[ezeke]

Re: 1975 85 hp johnson waterpump burndown

The water pump itself has three areas of concern: One is that the air bleed hole at the top of the liner has to be clear so that the pump can prime; second is that the rubber grommets where the water tubes are inserted are properly inserted so that they don't block the flow of water; and third, that the liner is correctly aligned when inserted into the water pump housing.

The water flow is as shown in the thumbnail.

If the cooling system was working before, look at the pump, if not, check the system including the vernatherm.