Powerhead removal

[Waverider17]

Hi Everyone,

I have a 1989 Mercury 60hp OB240262. I'm attempting to remove the powerhead and the manual calls for the shift link attaching nut to be removed but there's no picture for reference and when I look around the area I can't see anything obvious. I've loosened 8 x nuts around the perimeter but there's also mention of 3 x cap screws to remove from underneath the exhaust plate, again with no picture for reference. Can anyone point me in the right direction?

 

[jimmbo]

First things first. What Manual are you using?

Likely #10

https://www.marineengine.com/parts/mercury_marine_parts/sn/0B240262/1060412BD/336_120

 

[Waverider17]

It's an original Mercury service manual covering models 45hp to 115hp from 1965 through to 1991.

 

[Chris1956]

Shift link nut is #10 in his diagram. If you don't remove it, you will pull the shift rod out of the midsection. The others you will need to look for.

 

[Waverider17]

Thanks for you replies, I've located and removed all of the nuts that secure the powerhead. The reason for attempting this is in an effort to free the driveshaft from the powerhead as it appears to have welded itself which I found out after attempting an impeller replacement. I can see a gap all of the way around the exhaust plate as you'll see in the photo and I'm using a 500kg electric hoist on a heavy duty gantry with the lower unit strapped down tight as I was lifting the entire boat and trailer off of the ground. I've got the winch wound up as much as my nerves will take but I can't get the powerhead to budge more than 1/4". I've got time and patience but is this ever going to budge or am I wasting my time?

 

[racerone]

How many nuts on your work bench?

 

[Chris1956]

There might be a nut or two under the carbs.

However, It makes a whole lot of sense to pull the gearcase. There should be 5 nuts, a bolt or screw that holds the zinc anode plus one more bolt under the anode. you can install the gearcase really easy, later, if you pull it now.

 

[racerone]

He clearly states that he was trying to do an impeller replacement .---Lower unit will not come off.----Should be 8 nuts on the work bench.

 

[Waverider17]

All 8 nuts have been removed without any fuss which was a nice surprise. What's baffling me is that I had the lower unit off last year to replace the impeller like I've done for the past 5 years and I greased the splines before assembly. I'm keeping the tension on constantly now, just wish I could see the driveshaft to get some penetrating oil up there.

 

[Chris1956]

Stick a can of penetrating oil, with a long tube in that slot and give the driveshaft a blast. I do not think it will do anything, but you never know.

Wood wedges can help as well.

 

[Waverider17]

If I could get the powerhead to lift a little more I could get to the driveshaft but at the moment the casting on the exhaust plate is obstructing any access. I'm going to get the air hammer out tomorrow and while I've got the tension on the hoist I'll see if I can use some vibration on the bottom of the powerhead studs to free things up. I tried with wooden wedges yesterday but I only had some CLS and it was too soft so I'm cutting some oak wedges tonight. I've got my holesaw and cutting torch in the corner of my workshop so it's coming apart one way or another but I've got a couple of months to go before I start destroying the mid section.

 

[Chris1956]

You could hang it upside down, by the gearcase. That would put pressure on both pieces that you want to remove, plus, gravity will cause the penetrating oil to run into the driveshaft/powerhead joint.

 

[Waverider17]

Thanks to everyone who gave their input into this. It took an electric hoist, DIY gantry, oak wedges, ratchet straps, 5 cans of penetrating oil blasted up the driveshaft with compressed air, 3 hours with an air hammer and pry bars and the sucker finally gave up and let go. May as well replace the upper mounts while it's torn apart and a long road ahead sourcing parts and getting her back together. That's enough for today though!

 

[racerone]

So was the driveshaft really stuck ?---Or those powerhead studs jammed in the exhaust housing ?

 

[Waverider17]

The driveshaft was the cause, there was corrosion on the splines even though I had applied a thin layer of grease before assembling after the last impeller replacement a year ago. I've taken the lower unit off and noticed a rubber O ring perished on top of the water pump housing so assume that salt water had been travelling up the driveshaft while it was spinning at high speed maybe. Once the bottom of the splined shaft was exposed I was able to drive penetrating fluid up there with the aid of compressed air and I used a piece of flat iron up against the drive shaft with a notch cut out of the end to insert a blunted chisel mounted in an air hammer to vibrate the hell out of it while the power head was under full tension from the electric winch.