65 hp driveshaft collar?

[charing]

iboaters:

I recently purchased a '76 Merc 650 with an old Lund I am rebuilding. The old motor started right up and produced over 120psi in each of her three cylinders, so I decided to make a run at still using her. First on my list of repairs was a new impeller, of course. I had no problem finding the nuts and bolts indicated by my Seloc manual, but when I tried to lower the lower unit, it stuck about five inches from the bottom of the exhaust housing. A few choice words and a little pressure pulled it loose, but I discovered that it had been held back by a splined collar which obviously fits over the splined end of the drive shaft, and is now sitting loose above the narrow section of the exhaust housing. The water tube is preventing it from coming entirly out of the exhaust housing. The driveshaft turned out to be the type with the guide pin machined into the top of the shaft. With a flashlight I can see that the collar fits into another splined component at the very top of the housing. Since none of the manuals or parts lists that I have accessed so far indicate the collar, I am in a quandary. Does anyone know what the heck that thing is, and more importantly, can I reinstall it without removing the exhaust housing? I am always appreciative of what you guys and girls have to say, and you will be hearing more from me soon, now that my Lund project is underway.

 

[GA_Boater]

Welcome aboard. Got a serial number so one of us can find a parts diagram?

 

[dwco5051]

I have the '76 650 factory manual in front of me and it does not show anything on top of the driveshaft like you describe. It almost sounds the way you describe it that someone made a drive shaft extension for some reason. What is the history of the motor? Do you know of any repairs made before?




View attachment mercury lower end001.pdf

If this diagram does not come through if you would send me a private message I can e-mail you a pdf of the factory manual lower end page.

 

[charing]

Serial number is 4382551. And I got the pdf; thanks dwco. Yeah, I am now eager to take another look up the exhaust housing. I spent tonight dismantling the lower unit through the water pump. It appears to have been replaced last time without all the parts - missing o-rings and seals around the drive shaft, no lower water tube seal, a good bit of silicone calk instead. I think that it must have sat idle for quite a while judging by the bees that took up residence in the exhaust system. Makes me wonder if the collar is a misplaced part that didn't really do anything but get in the way when I was removing the lower unit. That's all I know about what was done to it. I'm going to rebuild the pump, hopefully run it a bit and sell it off for a newer motor. I will likely be doing some long-distance commuting on a pretty remote lake and will need something pretty reliable. Can I remove the exhaust housing without having to violate the power head too much? Thanks for the responses. Great to have someone interested and knowledgeable to talk to.

 

[Faztbullet]

Its the upper slinger/seal parts numbers 78654A 1 and 86304

 

[charing]

Faztbullet:

About your information: the only slinger I can find in diagrams sits on top of the water pump cover. I removed that one from my motor in the process of replacing the impeller. I can't find part 78654A 1 in any diagrams or manuals to which I have access, and 86304 only comes up in a verbal reference as a "seal". If you could let me know where you got your information it would really be helpful, as well as anything you know about where they should go in the motor, what they have to do with the impeller replacement process, and what I have to do to extract them from the drive shaft housing and reinstall them would be really helpful. That's a lot to ask for I know, but I'm getting desperate, and anything you know adn are willing to share will be greatly appreciated.

 

[Faztbullet]

Items #32 and 33
http://www.crowleymarine.com/mercury-outboard/parts/675_17.cfm

 

[charing]

Faztbullet:

Both of those parts were in place on the water pump when I replaced it. Still looking for someone who knows something about removing the drive shaft housing. Can't believe it's not covered in a manual. Thanks for you time.

 

[merc850]

You remove the powerhead from the DS housing by undoing nuts (3 per side) at the joint, disconnect fuel line and any items that join powerhead to DSH; then lift the powerhead off the DS housing with a lifting ring in flywheel.

 

[Faztbullet]

Items 32 &33 go on splines on top of driveshaft

 

[charing]

iboaters:

I think I figured it out! The motor appears to be a 20-inch model shaft adapted from a 15-inch shaft model; the part stuck in the upper section of the drive shaft housing being the drive shaft extension necessary to achieve the adaptation. Using a shaved down dowel, I have been able to insert it back into the power head without removing it. I am ready to go, installing the rebuilt lower unit, except that now I notice that both studs that extend out of the drive shaft housing to connect the lower unit are in really bad shape. Threads are really stripped on one, and non-existent on the other making them useless. Has anyone ever replaced these studs? They appear to be turned into the drive shaft housing using very elongated hex-heads. Don't know how involved I want to get. It might be easier to switch out the housing for a used one. Your advice in locating one would be greatly appreciated.

C.