LOWER UNIT

[imported_love to fish]

I have a 25-ft Boston Whaler with two 1991 150 HP Johnson outboards and I want to change both water pumps.
I'm having a problem removing lower units on both motors.I removed the five bolts plus removed the one hidden under trim tab and also removed shift linkage pin. I'm wondering if there's another bolt to remove. when all bolts are removed I can wiggle lower unit side to side about a 1/2" but will not come apart. I do not want to put pressure on lower unit. I stood on lower unit to try to break free, but no results. Maybe there's corrosion on the splines of the shaft. A few months ago I change the water pump on my 140 HP Johnson with no problems. Can someone help with this problem.

 

[ezeke]

Re: LOWER UNIT

Have you disconnected the shift rod from under the carburetors?

 

[imported_love to fish]

Re: LOWER UNIT

Yes, I have disconnected the shaft rod, but still will not come apart, note this boat was used for salt water fishing.

 

[ezeke]

Re: LOWER UNIT

Did you remove the anode bolt by mistake?

If the drive shafts were inserted with heavy grease or too much grease they can seize hydraulically in the crankshaft and be difficult to remove.

One thing that sometimes works is to leave the bolts a little loose and run the motor a little. The case is usually unbalanced enough that the wobble will loosen the shaft.

Another way is to use shims to keep the motor aligned with the gearcase and gradually bring the drive down. The kind of shims that they sell at lumber yards for framing work well.

 

[imported_love to fish]

Re: LOWER UNIT

Did you remove the anode bolt by mistake?

If the drive shafts were inserted with heavy grease or too much grease they can seize hydraulically in the crankshaft and be difficult to remove.

One thing that sometimes works is to leave the bolts a little loose and run the motor a little. The case is usually unbalanced enough that the wobble will loosen the shaft.

Another way is to use shims to keep the motor aligned with the gearcase and gradually bring the drive down. The kind of shims that they sell at lumber yards for framing work well.

 

[imported_love to fish]

Re: LOWER UNIT

The problem is corrosion on shaft splines, I was able to remove one lower unit so far by forceing lubricate where shaft goes up into the motor's spline and use a hammerand flat head punch to tap on the shaft, I put motor in gear and rotated and tap the shaft until L U came apart, but on the other hand the second motor is shaft spline is corroded worst. You have a good ideal to run motor, I'll give it a try and let you know whats happen. What type of grease would you recommend to use on the shaft when reinstalling. i will install a complete water pump kit and change out water pump at least every two years. Thanks for your info a big help. I'll let you know what happens.

 

[ezeke]

Re: LOWER UNIT

The manuals say to use OMC Moly Lube. You coat the sides and not the top of the shaft. I try to be sure to replace the 'O' ring with a new one.

I'm not at all confident as to what Moly Lube is, but I know that you sometimes get a small packet of it with a BRP complete water pump kit. It is probably marine wheel bearing grease with an additive like molybdenum disulfide. Whatever it is it has to be able to withstand heat and friction.

 

[mikesea]

Re: LOWER UNIT

i have removed all bolts and run the engine, like said ,it often shakes enough to loosen,dont run it long, you will overheat the powerhead but also friction will build up rapidly in the waterpump and likly melt the housing,have someone ready to shut it down after 20 to 30 seconds,then give it a couple minute and try again,try it first without shims,but after a couple tries,put four in at the corners and while running ,tap em in a bit,not to heavy though.for totally stubborn shafts,i have taken an 1 and 1/2 hole saw made a plug in the side of the housing,then used an air hammer and beat on the shaft ,rotating a little at a time,been very successful.but there are the ones where you got to cut the shaft,leave that til later

 

[ezeke]

Re: LOWER UNIT

I have never run a motor without water like that, mikesea.

I just loosen the bolts enough to make the gearcase hang a little loose. I think that any more than that would tear up the impeller housing for sure.and could do even more damage.

BTW, there is no reason for the motor to be in gear while you do this.

 

[imported_love to fish]

Re: LOWER UNIT

I have never run a motor without water like that, mikesea.

I just loosen the bolts enough to make the gearcase hang a little loose. I think that any more than that would tear up the impeller housing for sure.and could do even more damage.

BTW, there is no reason for the motor to be in gear while you do this.

 

[imported_love to fish]

Re: LOWER UNIT

I have never run a motor without water like that, mikesea.

I just loosen the bolts enough to make the gearcase hang a little loose. I think that any more than that would tear up the impeller housing for sure.and could do even more damage.

BTW, there is no reason for the motor to be in gear while you do this.

 

[imported_love to fish]

Re: LOWER UNIT

Guys, I just return from work yesterday morning and I starting working on the second L U, and I used wooden wedges and the LU came apart but the shaft stayed, wedgeing the LU the shaft pulled out of the gear case. Now I'm still trying to pulled shaft with weight tied onto the shaft, but this shaft is real stubborn, I'm not giving up, that shaft will not win, do you guys have any clues on how to get that stubborn shaft off.

 

[Cricket Too]

Re: LOWER UNIT

Why wouldn't you just run the motor with the ear muffs on it, so as not to overheat anything? Your still gonna get the vibration you need.

The drilling the housing with a hole saw sounds interesting. Where do you drill the housing in order to get to the shaft?

 

[imported_love to fish]

Re: LOWER UNIT

The lower unit is removed from the motor but shaft did not come with the lower unit the shaft must be welded to the block of motor, I have 568 pounds of weight hanging on the end of shaft, with that much weight the shaft should come off. You have to picture the lower is removed from motor, now the shaft stick out about four inches and there's a 3/8" pin hole at the end of shaft and that's where I tied this weight to. I don't know if I put a lot pressure to pulled the shaft I break the shaft housing.

 

[G DANE]

Re: LOWER UNIT

I made a homemade puller, by drilling a hole big enough to let the driveshaft pass through in two blind muffs for water pipe. Then I cut a piece of tube and cut threads in both ends. I measured the tube so long that the upper blind muff rested against the end of the cranckshaft up in mid section, the lower end reached a bit out of the mid section. I ground a little mark in the driveshaft over the waterpump seal, and put a wise grip on real tight. I then unscrewed the lower blind muf, pulling driveshaft out of cranck. It was on a chrysler, much smaller motor. I dont know if your motor has room for a water tube, big enough. Otherwise same method can be used after you pulled the powerhead, with shaft hanging from it. Maybe you could clamp a sledge hammer to it and drag it out that way.