Need advice on separating 85HP Johnson lower unit from powerhead

[tomd514]

I noticed last season that the lower unit lube was cloudy and I want to replace the lower unit seals. I have removed all the bolts (2 on each side, 2 (one long and one short) under the trim tab. I also freed the shift rod under the carbs. The lower unit will not separate from the upper unit. It is loose but the separation is approximately 1/16th of an inch. I spoke to the guys at the marina and they said they drive in wedges to split the cases. Is there a preferred spot to insert the wedges where I won't crack the case?<br /><br />thanks,

 

[ezeke]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

There should be a bolt in front of the trim tab, not under it. Did you get that one?

 

[ezeke]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

The strongest position on the lower unit is where the bolt is located in front of the trim tab. You need to balance force at the front, though, and there is not much space except at the very front. <br /><br />If you go to your building supply store and look in their drywall section, you will find wood shims, used for leveling.<br /><br />Work two or more in from one side, depending on space and then drive one from the other side between them. Try to keep an equal amount at the front of the lower unit.<br /><br />Risky business. Move your shift lever first and make sure you have released the shift shaft.

 

[ledgefinder]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

If you got all the bolts, I assume the driveshaft splines are sticking.<br /><br />Is the motor running? If it is, put the 4 side bolts back on, leaving them about 3/8 of an inch loose on all four. Back the boat into the water, but leave it on the trailer with the strap on. Start the motor, shift into forward, and give it a little gas. Throttle back down to idle, put it in reverse, and give it a little gas. Do this back and forth three or four times, then pull the boat out. The lower unit should have dropped down.<br /><br />When pushing forward, the prop/lower unit tries to rotate forward out from under the midsection. The forward part of the LU hits the midsection, and the reaction force pulls down on the driveshaft. By running the motor, you're also adding heat & vibration/shock loads to work on those splines. <br /><br />I haven't had this fail yet & haven't had to give it much gas either. <br /><br />Good luck!

 

[Hooty]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

There's a total of seven fasteners (bolts & nuts) and the shift linkage that have to be removed before the gear case will drop down. Did ya get 'um all?<br /><br />c/6<br />Hooty

 

[tomd514]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

thanks to all replies. here's all the bolts I've removed:<br />4 side bolts<br />1 long bolt (forward of the trim tab) <br />1 holding the trim tab in place<br />1 accessable after the trim tab is removed.<br /><br />Ledgefinder: Yes, the motor is running, do you think I could achieve the same results with using a barrel of water? <br /><br />thanks again.

 

[Hooty]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

Yep. That's the seven fasteners okay. <br />G'luck.<br /><br />c/6<br />Hooty

 

[Basstactics]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

What about the shift linkage which I believe has to be unfastened from under the carbs?<br /><br />oops! just noticed that you said you unhooked the shift linkage in your original post. Sorry, my mistake

 

[ledgefinder]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

If you put an 85hp motor in gear, while it's in a barrel, you'd better stand back a ways...

 

[ledgefinder]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

My last answer may not have been too helpful...<br /><br />If it's a hassle getting the boat/motor to a launching ramp, you could try running it in a barrel or just on the flushmuffs. It may not take much to break the crud on the splines loose. You'll generate some shocks just shifting in and out of gear. <br /><br />If you run it in a barrel, be advised the water level has to be WELL ABOVE the level of the cavitation plate. The water pump is above the plate, and you have to get the water level up as high as the pump. Otherwise, you burn the impeller out (speaking from sad experience...).

 

[tomd514]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

thanks to good advice from ledgefinder, hooty and ezeke, I convinced the lower unit to separate. I used wooden shims, gently hammered in on both sides until the gap got big enough to drive in bigger wedges. <br /><br />Can you recommend the appropriate lubricant I can apply to the drive shaft splines to avoid this happening again?<br /><br />Thanks again for all your help.

 

[Hooty]

Re: Need advice on separating 85HP Johnson lower unit from powerhead

I use Pennzoil Multipurpose Marine Grease but any good waterproof grease will work. Grease the splines good but do not put grease on the end of the driveshaft. Also, there should be an o-ring that slips over the shaft to seal off the splines from water coming up the shaft.<br /><br />c/6<br />Hooty