mercury lower unit removal

[vyger]

Hi,
I have a 1980 7.5 Mercury which sat for some time. I have redone the carb and got it runnung but now see it needs a water pump. I took off the 2 nuts holding the lower unit on but it's not coming off. I have done a few water pumps and know that the shift linkage needs to be free but I haven't seen a linkage setup like this before. Underneath the carb is a gear and the linkage comes from the gearcase and terminates there. It looks as if it is pushed up into a spline in the center of a gear which connects to another gear which is mounted on a square bar that runs to the shifting mechanism on the side of the engine but I don't see how it comes out. I thought i could just pull it down and it would free itself from the spline in the middle of the gear but it doesn't. Does the shift bar have to come out and the gear taken off the linkage from the top ..Any help woud be appreciated..
.

 

[shearpin]

Re: mercury lower unit removal

did u remove the 2 nut's under the cav. plate? one u can see the other is under the anode plate trailing the prop.

 

[vyger]

Re: mercury lower unit removal

Yes they were removed ...but the lower unit does not seem to budge.That's why I'm thinking something else is holding it ..like th e shifting rod that goes to it...can't see how to loosen it from the top tho???

 

[golfcarmad]

Re: mercury lower unit removal

Help,I actually have the same engine in the kitchen right now and I cannot remove the lower leg-any advice????
many thanks

 

[Motor Boater Bill]

Re: mercury lower unit removal

I haven't done a 7.5 of that year, but the small Mercs I have done have been consistent in that the shift shaft has a splined coupling in the middle to let it come apart. Either that may be stuck, or the driveshaft may be stuck in the crank where it is splined in. However, it is also possible that you have missed a bolt or nut that needs to be removed. They can be very well hidden! On the Merc 20 hp you have to remove the anode plate by reaching through a hole above it with an allen wrench, then you can see the final nut hidden under the anode plate--devious!

It's also possible the studs are corroded into the LU.

Check the parts list you can view here:

http://www.mercruiserparts.com/selectModels2.asp?type_id=MERC

 

[golfcarmad]

Re: mercury lower unit removal

much appreciated for link.Looked everywhere cant find anyhting to undo,may just have to take a BIG hammer to it!! regards n tks

 

[vyger]

Re: mercury lower unit removal

Yes ...thanks for the link...as I suspected , looks like the shaft for the shift linkage is splined at the top and should just pull down from the selector gear. As you suggested , either that or the driveshaft may just be stuck...The lower unit split in the rear but not at the front where driveshaft and shift linkage are...

 

[Texasmark]

Re: mercury lower unit removal

Don't know when Merc went to stainless shafts on that engine. I had one once and put an impeller in it but that has been a long time ago. I think it was a '70's vintage.

I know there are 2 nuts on the side (one per side) and as Shearpin said, usually one more at the rear. On engines with a trim tab you have to remove it to see it, but that engine doesn't have a trim tab.

On some engines there is one located at the front.

Can't help you with how many shift shaft pieces there are.

Can't get in there to spray penetrating oil which would really help.

Using a hammer is risky

If the back is coming down and not the front it's either a screw you missed, or the shift shaft is holding you back. I don't know of anything that would do that other than the clamp under the carb on the shaft.

HTH; best I can do.

Mard

 

[golfcarmad]

Re: mercury lower unit removal

Yes ...thanks for the link...as I suspected , looks like the shaft for the shift linkage is splined at the top and should just pull down from the selector gear. As you suggested , either that or the driveshaft may just be stuck...The lower unit split in the rear but not at the front where driveshaft and shift linkage are...

 

[golfcarmad]

Re: mercury lower unit removal

how have you got on with removal??? i hope to have another gp at mine later this week,like yrself,i m afraid to take a big hammer to it-if i'm missing something!! regards golfcarmad