lower unit removal problems on 850 mercury.

[jabrmakeea]

have removed all bolts and nuts separated, lower unit and have exposed water pump ect, but main shaft will not drop out of leg seems to be stuck or locked with something else, is there something i am missing? any help would be appreciated. All i wanted to do was replace the water pump but have been pulled up in a sharp way with the removal. Done everything i could find on the net as per instructions. PLEASE HELP>>

 

[Texasmark]

Re: lower unit removal problems on 850 mercury.

Since you are down to having the water pump visable, you got all the screws out/nuts off. There are 3 things connecting the lower unit (like the ad on the right of my screen just now of a lower unit for $745 with 3 year warranty).

Starting from left to right of that picture, left is the shift shaft..3/8" diameter hex shaft that mates to a hex shift socket on the end of the shift rod in the mid section...twisting is how the gears are selected and each is detented and easily felt.

Next you see the silver (in the pic, some are plastic) water pump/impeller cover with the drive shaft (has a splined top that fits into a splined connector on the bottom of the crank...in the block) coming out of it, and just to the right of that, still on top of the water pump cover is a black circular "stove pipe" which is the water outlet, connecting to a copper tube that sticks into the bottom of the engine block.

On some engines there is a black plastic tube that connects to the speedometer inlet (1/8" dia hole roughly) which is below the antivent plate at the very front of the housing.

That's all there is in there. Since you are as separated as you say you are, one would suspect that you have the shift shaft and drive shaft separated from their mates and the only thing that could hold you (doubt it) would be the water supply tube.

Mark

 

[jabrmakeea]

Re: lower unit removal problems on 850 mercury.

thank you for your time will investigate further tonight once home from work, appreciate your input, I can hear the drive shaft rattle around inside the leg but it all will not let go, once again thankyou Texasmark..

 

[Bondo]

Re: lower unit removal problems on 850 mercury.

thank you for your time will investigate further tonight once home from work, appreciate your input, I can hear the drive shaft rattle around inside the leg but it all will not let go, once again thankyou Texasmark..

Ayuh,... The vertical drive shaft Don't come outa the lower unit, unless ya pull the guts outa the lower, 'n unscrew the pinion gear from the bottom of the vertical shaft...,

 

[merc850]

Re: lower unit removal problems on 850 mercury.

Here's the LU setup do not pull out the shiftshaft (at front) or you will have to remove the bearing carrier to reinstall shift cam.

 

[Texasmark]

Re: lower unit removal problems on 850 mercury.

Here's the LU setupView attachment 119634 do not pull out the shiftshaft (at front) or you will have to remove the bearing carrier to reinstall shift cam.

All this stays with the LU and comes out with it as a unit. Go to the for sale lower unit ads on this site and look at a picture of one completely assembled (like I made reference to) and see for yourself what it looks like when it comes out....the gear case may be of a slightly different shape, but the interconnect parts are essentially the same.

Mark

 

[jabrmakeea]

Re: lower unit removal problems on 850 mercury.

my particular engine seems to have the spline gear shift rather than the one in the diagram provide guys, haven't had a chance to get back into it yet but will do tomorrow, not sure if you misunderstood merc850, i am not wanting to remove anything from the lower unit just separate it from the leg to enable me to replace the water pump, i really appreciate your help guys and will get back to you blokes tomorrow with an update on how i am going. As you said Mark the parts you described seem to be all unattached but it still seems to be solidly anchored by something internally up in the leg,

 

[jabrmakeea]

Re: lower unit removal problems on 850 mercury.

may have misread diagram does look the same
on second thoughts!!

 

[Texasmark]

Re: lower unit removal problems on 850 mercury.

Both shafts (shifter and drive) twist to function and are splined. Only thing I can come up with is maybe the shift shaft in the mid section didn't separate from the shift shaft coming out of the lower unit and it is stuck on there.....meaning that you tore up something at the top of the shift shaft to get the lower unit out as far as you did.

Get your flash light and look at the shift shaft coming out of the lower unit. It should be the splined end of a 3/8" rod and only stick up from the lower unit roughly an inch. If you see a joint and a long rod attached then what I said happened and explains why you cannot come completely out. Separating the two sections at that joint will allow it to come on out then you can see what you need to fix on the top end of the shift shaft.;

HTH,

Mark

 

[jabrmakeea]

Re: lower unit removal problems on 850 mercury.

that all seems to be as you said Mark, only protrudes out of the lower unit by about an inch , the longer section is still attached at the top and runs through the engine pivot ok. No damage there.

 

[jimg984]

Re: lower unit removal problems on 850 mercury.

it probably has pulled outta the shift cam in lower unit,,, scroll back to post #5

 

[jabrmakeea]

Re: lower unit removal problems on 850 mercury.

main drive shaft has jammed or failed to release at the top i have been told by mechanic, have been told that now power head removal is necessary to see why the bloody thing is stuck, i will know a boat engine inside and out by the time i am finished with this water pump replacement, lolol

 

[Chris1956]

Re: lower unit removal problems on 850 mercury.

If the driveshaft is rusted into the crankshaft, you will not be able to remove the powerhead. Can you hang then motor upside down, with the top of the motor 1" off the ground? If so, spray the driveshaft with good penetrating oil and let her hang a while. The oil will run down into the driveshaft/crankshaft joint, and hopefully loosen it up. Next come the wedges to gently force her apart.

 

[jabrmakeea]

Re: lower unit removal problems on 850 mercury.

have got the power head off and have now been able to remove shaft, all these drama's because of one tiny little sleeved collar/seal can you frigging believe it. Gaskets and water pump on order now we just have to clean it all up and reassemble.. Even after all of this the experience has been good and will know more about my boat than most, appreciate all your help guys will update you once i have her back together. at least i have time to clean everything up and make sure all the gasket faces are good while i wait for the parts, found the cooling issue i was looking for as well, previous owner must have came across the same issue when trying to fix water pump and instead of fixing just put it back together after they had put a hole in the water pump housing sleeve with a screw driver, thanks for the input guys it was a big help..

 

[merc850]

Re: lower unit removal problems on 850 mercury.

Grease the driveshaft and shiftshaft splines with a high quality marine grease so the next time it will be easy.

 

[Texasmark]

Re: lower unit removal problems on 850 mercury.

Grease the driveshaft and shiftshaft splines with a high quality marine grease so the next time it will be easy.

But just put on a thin coat so that it doesn't pack up in the interface and keep you from completely engaging the upper and lower splines.

Glad you got her going and really glad you found the root cause of your problem in the first place.

You think you had a problem with not knowing what the previous owner did, try buying a farm tractor that is 50 years old...that can be a real experience.

Mark

 

[jabrmakeea]

Re: lower unit removal problems on 850 mercury.

really appreciate your help fella's, grateful Aussie, will let you know how all goes in a week or so after i get the parts. rgds Brad.