Johnson V4 powerhead removal

[Robert Harris]

Just started the process of rebuild on a 1980 Johnson V4 115.Got my factory manual and removed all the necessary nuts and bolts..etc. for the powerhead but can not get off.Searched the forums with no luck on a similar problem.It is loose from the bottom plate on all sides.Matter of fact I can lift close to half of an inch on both sides and front and back.Seems like is hung up in the middle somewhere.Is it possible the driveshaft is seized or so something.<br />All help is appreciated, Thanks

 

[93bronco]

Re: Johnson V4 powerhead removal

just a thought, what about shift rod at front of motor. that has to be disconnected. that might also account for the travel, i count 14 nuts/bolts + shift rod. i could be wrong im looking at my 1978 omc manual

 

[Joe Reeves]

Re: Johnson V4 powerhead removal

RH...... I believe 2K has you steered in the right direction (shift rod). If the driveshaft was hung up in the crankshaft splines, you wouldn't be able to lift the powerhead that far up.

 

[Robert Harris]

Re: Johnson V4 powerhead removal

Thanks for the advice, but I did disconnect the shift linkage.That was the hardest part, a real pain to get to,I don't know how I'm going to get that screw lined back up, but I'll deal with that later.It shouldn't matter what gear it is in, right?<br />I can get it to lift a little bit either from the front or the back, but not both at same time,which led me to beleive something was "hung" up in the middle.It seemed to gain a little more clearance the more I played with it till it reached a stopping point of about 1/2 inch.<br />This is my first attempt at rebuild so I'm not really sure of how it all fits together.Could I have possibly lifted the driveshaft out of gearcase or bent something in attempt to pull? <br />Got to go to work, will read posts later.Thanks for the time.

 

[bonitoman]

Re: Johnson V4 powerhead removal

RH, Try to drop your lowere unit first before you pull the powerhead. You have about six bolts on the lower unit and usually one under the carb. there is usually one under the trim tab . Once you drop your lower unit the driveshaft is part of this now you can pull your power head if you have removed those. I say this cause when you rebuild it you should put a new waterpump in the engine with new thermostats and clean your carbs. Many people will rebuild and engine and not change the waterpump or thermostats or rebuild carbs. Most of the time this is what causes the engnine to go in the first place. When you drop your lower unit you can inspect the impellar to make sure it is all there and no rubber pieces have broken off and blocked water passages.

 

[Robert Harris]

Re: Johnson V4 powerhead removal

Thanks Bonitoman,I guess I'll give that a try.<br /><br />Pulling the gearcase doesn't seem like that big of a deal.Like you said, I need to change waterpump anyways.Will the driveshaft and shift rod come all the way out with the lower unit?I was just hoping to do this one step at a time before I have everything apart and on the floor and the wife nagging me about "are you sure you know what you're doing?" <br /><br />Thanks for the time.

 

[93bronco]

Re: Johnson V4 powerhead removal

yea it should all come out, hope fully the inner exaust housing will stay in. take care not to damage shift rod

 

[wilde1j]

Re: Johnson V4 powerhead removal

Don't rotate the shift rod while you have the LU off (you will change it's effective length if you do).

 

[Robert Harris]

Re: Johnson V4 powerhead removal

Thanks all for the advice.<br /><br />Pulled the lower unit with no problem and the powerhead came right off.I don't know what was "hanging" up, but all is well now.<br /><br />Now the real fun begins with the teardown and rebuild.I'm sure I'll need help once I get into it elbows deep.This is a great site and I really appreciate the help.

 

[bonitoman]

Re: Johnson V4 powerhead removal

When doing your rebuild it is important to stay organized. Take a plastic cup or glass and stick the lower unit bolts in there and label the cup lower unit bolts. Do the same for head bolts,stator,coils,Put the cups in order so If you are looking at the top cup that is your stator and screws .This way it makes it easier when reassembling. I do know if you are changing rod bearings and back then omc used loose bearings so be careful when you pull the wrist pin out of the piston and connecting rod cause you will see many bearings. Make sure you count them before you store each one in a small plastic see through bag. Good Luck It is really not that difficult.

 

[mrc]

Re: Johnson V4 powerhead removal

Staying organized is major good piece of advice.<br />My additions.<br />1) I bought one of the medium sized parts drawer cabinets with different sized drawers for the parts. Less likely to tip over and spill.<br /><br />2) Take lots of notes including the order in which you disassemble the motor and reverse the order during reassembly. It is not fun to discover some part that needs to be attached that belongs underneith some already sealed gasket. Or some part that needs to be reattached that you cannot get at because of interernce from another part. Even the factory manuals do not give complete instruction in this regard.<br /><br />3) Get factory manual if at all possible (not clymers or seloc) With the factory manual it will be for the exact year and model of your engine. Thus the pictures will not be some hodgepodge of different models and years.<br /><br />4) Take Photos and copious notes of hose and wireing routing.<br /><br />5) Before sealing any gasket make sure all nuts/bolts behind gasket are torqued to specification. Have torque wrench handy and set to specified torque for nuts/bolts which will be used to reassemble the gasket/seal.<br /><br />6) Take your time and be thorough on disassemble and you will have an easy time during reassembly.<br /><br />Tricks:<br />1) the bearings between the rod attachment point on the crankshaft are usually keyed with a pin on the block. It can be tricky on a 3+ cylinder engine to get all those bearings seated during reassembly. <br /><br />Trick: Rotate the bearing until the reciever hole is halfway covered by the block. Take a felt tip sharpie pen and mark the opposite side of the bearing. Move the mark to to the top and you should be in the right neighbourhood. Also if the pin on the block is not lined up with something (like tapped bolt holes) use should mark that spot as well.

 

[Robert Harris]

Re: Johnson V4 powerhead removal

I probably won't tear into this thing till after Christmas.I'm hoping to get a digital camera so I can take lots of pics for reassembly.<br /><br />I probably should start a new thread but I'll throw these questions out anyway.I've been told the first thing to check is the crank.If that is no good,no sense in proceeding.Not really sure I'll know if good or not.<br /><br />Next is the boring.Going for a .30 bore on all cylinders with new pistons.Does the shop also have to do something with the intake and exhaust ports? Also, what is best for pistons, aftermarket or original?<br /><br />If I need to move this to a new topic, let me know.Thanks for the time.