1988 force 125 water tube to water pump

[digitalman]

My 1988 125 force overheats. I dropped the lower unit, Replaced impeller. There doesnt seem to be a close fit from outlet of waterpump housing to the nylon portion on the water tube located in intermediate housing. is there supposed to be a gasket, rubber washer or somehting to make the fit snug? I dont have a clue and cant seem to find a diagram detailed enough to show

Help? and where would I get the missing part?

 

[Frank Acampora]

Re: 1988 force 125 water tube to water pump

on the waterpump outlet there should be a white plastic adapter with the hole inside it tapered to ease installation. The water tube is an easy fit in this adapter. It goes all the way down into the adapter where the hole is the same size as the tube. There is nothing else to seal it. Any leakage cools it.
Sometimes, exhaust melts the adapter and compromises the seal. This part has been used forever; it's the same in all 3 and 4 cyl before 88 (I think)waterpumps and should still be easily available.
Was the replaced impeller worn? Enough to pump insufficient water?
When you replaced the impeller, did you check the pump housing for corrosion damage? Did you also remove the SS plate and gasket below the housing and check the lower plate for corrosion damage. This lower plate has a thin wall separating inlet from outlet of pump. If it is corroded to the point where it is not sealed by the gasket, water will short- circuit from the outlet to the inlet, reducing the amount delivered up to the engine block. Also, if the back end of this plate (the end with two screws holding it down) is not flush to the the gearcase, it will leak air and the waterpump will not put out sufficient water. Some have an O ring in a groove, some don't. If yours doesn't, seal it with a bead of silicone RTV.

Did you replace the gasket which almost always gets destroyed during removal?

All these parts should be available at any Mercury dealer. You may even be able to pick up a water pump rebuild kit right here at i boats.

 

[digitalman]

Re: 1988 force 125 water tube to water pump

Thanks for the advice. The problem best I can tell is that the nylon adapter is he wrong one for the 125. I dont know history of the engine but dont think it has be pristinely kept. The tapered end has close to 1/8 inch clearance..ie there is that much gap between pump outlet and the nylon. and I suspect the 120hp nylon guide was used instead of 125.

I ordered the complete rebuild kit including the housing, impeller, plates, gaskets and the correct nylon adapter and will rebuild entire pump assembly. Wasnt able to find on Iboats but found source on Ebay.

Also I dont think the ears supply enough water output for the force on a test, so I am using a make-do test tank instead. Read several threads that Force outboards have trouble with ears as a water supply..so taking no chances. I flushed lower uinit with fresh water, no clogs, and then flushed remainder of engine by supplying fresh water directly to the supply tube in the main engine at intermediate housing, as the lower unit is still removed. No issues I can see, water flows thru and exits what would be exhaust. Thermo was also replaced.

Just waiting on the mail man right now. Will provide results once install is done. Any more advise would be helpful.

 

[digitalman]

Re: 1988 force 125 water tube to water pump

Thanks for the advice. The problem best I can tell is that the nylon adapter is he wrong one for the 125. I dont know history of the engine but dont think it has be pristinely kept. The tapered end has close to 1/8 inch clearance..ie there is that much gap between pump outlet and the nylon. and I suspect the 120hp nylon guide was used instead of 125.

I ordered the complete rebuild kit including the housing, impeller, plates, gaskets and the correct nylon adapter and will rebuild entire pump assembly. Wasnt able to find on Iboats but found source on Ebay.

Also I dont think the ears supply enough water output for the force on a test, so I am using a make-do test tank instead. Read several threads that Force outboards have trouble with ears as a water supply..so taking no chances. I flushed lower uinit with fresh water, no clogs, and then flushed remainder of engine by supplying fresh water directly to the supply tube in the main engine at intermediate housing, as the lower unit is still removed. No issues I can see, water flows thru and exits what would be exhaust. Thermo was also replaced.

Just waiting on the mail man right now. Will provide results once install is done. Any more advise would be helpful.