How do I replace the impeller on my 1973 omc 120hp?

Question

I need to replace my impeller and do not even know where it is located or how to get at it????

It is a 1973 OMC 120hp electric shift.

Does anyone have an exploded veiw of these parts?

Thanks in advance

Answer 1

The hardest part about this is not to ruin the wires. You will need an old control cable core and a knife blade electrical connector. Solder the connector  and slip it on the shift lead where it comes thru the transom-leave the rubber sleeve with the controll box side of the wires. Next. Spray the wire from transom to your new feeder wire with silicone  lube. Tilt the lower about 1/2 way up/ --remove the back cover. Take the little spring off the elect shift wire. Spray silicon on the shift wire where it comes thru the transom and pull it thru till you have the feeder wire in hand. Now remove the lower from the intermediate. The water pump is under the big lump on the top of the lower where the drive shaft comes from. Save the plastic water tube guide, grease up the seal the water tube went in. set it aside. Your new impeller will have to spin into the pump housing in the direction the motor turns. If you don't  have anything left of the old impeller or know what direction that is-pull the coil wire and flashlight in hand have some one crank the motor. Interrperate this info correctly or you will be doing this all over again.   Some times the old pump will leave an imprint on the wear plate. Use the omc/johnson/evinrude carmel colored soft seal on everything. grease up the impeller and test the keyway is actually turning the pump impeller. Goop up the end of the drive with "John Wayne's  Cutchens magic formula." (1/3 white grease 1/3 anti sieze 1/3 STP in a blender.)  block the unit under the upper gear case and start feeding the shift wire. Grease the wire where the 3 ridge seals are. Move the two gear cases closer and feed the wire as you go.  When the wire gives you 3 distinct bumps it is home. Bolt up the unit, hook up the little spring and put the back cover on.  You know the lower takes electic shift oil and the top takes  80wt gear oil. Now is the time to fix seals. If it shifts backward, switch the wires. Don't run dry-ever.

Answer 2

will's got ya covered.

the schematic diagram is available at http://www.shop.evinrude.com click on "online parts catalogue" drill down to your year/model

the "omc/johnson/evinrude carmel colored soft seal" is called "OMC gasket sealant", you can get it at "http://www.ishopmarine.com" , coat the retaining bolts with it else you might have to cut 'em off next time.

manual calls for "OMC adhesive M" on the joint between lower unit and exhaust housing, it's been replaced with 3m 847 -- permatex #2 works just fine but harder to remove next time.

ishopmarine has the 847 too, and "Molly Lube" for the drive shaft splines (in case you can't find that "john wayne" formula).  Don't forget the o-ring on the drive shaft just below the splines (check the diagram to be sure your model has one).  Keeps water out of the splines.

not completely sure about your model (check the diagram), but later 70's motors have two bolts up under the antiventilation plate (over the top of the propeller), torque tab covers one of 'em.  score a line across the tab so you can put it back like it was.