Removing powerhead on 1972 Johnson 125

[imported_scott_r]

Hi, I need to remove the powerhead on a 1972 V4 Johnson 125. Exactly what bolts need to be removed before the powerhead can be lifted? Are there any precautions, tricks, or complications involved in separating the powerhead from the lower unit?

Thanks,
Scott

 

[Dhadley]

Re: Removing powerhead on 1972 Johnson 125

If you don't pull it straight up you can damage the lower part of the crank. It's best to pull it with a lifting ring on the flywheel or remove the lower unit first. Or both.

 

[jay_merrill]

Re: Removing powerhead on 1972 Johnson 125

One of the most important steps is to disconnect the shift wires. I don't own a four cylinder hydro-electric shift, so I am not sure where your wires pass down into the exhaust housing, but that location may be on the port side of the motor. Once you find them, you should see a pair of rubber boots with small tabs on them, covering the connection points. Pull those boots back to expose the connectors and then disconnect the wires. The connectors work like a "handshake" - rotate the two halves until they form a "v-shape" and you will see how they come apart.

You will also have to disconnect the choke knob assembly from the upper carburetor, and the throttle cable from the spark advance lever. On the electrical side, you must disconnect the yellow electrical harness plug and the positive lead from the battery to the starter solenoid. Be sure to check for any ground wires that may be attached to the powerhead - there should be one coming out of the electrical harness just before the yellow plug.

The mounting bolts (6) are located at the upper end of the exhaust housing, and can only be accessed by removing the front and rear exhaust housing covers. These covers will be fastened together with four philips head screws, and will be fastened to the lower cowl with four straight slot or hex head machine screws. Access to these screws will be from the inside of the lower cowl pan. In looking at a parts explosion, it looks like there is a 7th and 8th attachment point for the powerhead in the form of two studs that fit down into the exhaust housing adapter. This is similar to the three cylinder models, which have one stud. Before you try to lift the pwerhead, you will have to find the nuts that fit on these studs and remove them. If the four cylinder is built anything like the three cylinder motors, the nuts will not be easily seen - you may have to feel for them a bit.

Most importantly, get an OEM service manual before you do this work, if you don't have one already. If you need one, it is probably available right here at iboats.

 

[imported_scott_r]

Re: Removing powerhead on 1972 Johnson 125

Thanks for the info folks! The only reference in the Clymer shop manual on this particular issue is "22. Remove the fasteners holding the power head to the exhaust housing." No details on the quantity of fasteners, location, diagrams, figures, photos, etc. So you guys got me pointed in the right direction.

For future reference, there were 12 "fasteners" which had to be removed on this particular unit (1972 Johnson 125 HP) in order to separate the powerhead from the exhaust housing adapter. Six (6) main bolts along the sides, three on each side toward the aft end of the powerhead; two (2) more bolts along the sides, one on each side forward of the main bolts; two (2) nuts on studs at the forward end of the powerhead; and two (2) nuts on studs at the aft end of the powerhead.

The two studs at the aft end of the powerhead were particular difficult to identify as they are hidden under the thermostat housing and found essentially only by "feel."

Thanks again!

 

[jay_merrill]

Re: Removing powerhead on 1972 Johnson 125

Thanks for the info folks! The only reference in the Clymer shop manual on this particular issue is "22. Remove the fasteners holding the power head to the exhaust housing." No details on the quantity of fasteners, location, diagrams, figures, photos, etc.

Yup, and in that, you have just discovered why the only way to go is with an OEM manual. I own a couple of Clymer and Seloc manuals. One is collecting dust on a shelf in my workshop, and the other is underneath the base of one of my computer monitors, along with a couple of other useless publications!