Disassembly of '78 OMC 800 Bearing Housing

[dhughes214]

Hey guys. Long story short, i'm trying to replace my bearing housing. it was cracked pretty good, and when I tried to remove the water pump housing it broke completely. I found one on ebay, and it's on the way. While i'm waiting for it though, I would like to start taking apart the old one. How do I remove the gear/bearing/shaft from the old housing. My manual is very vague. Thanks in advance.

 

[Howard Sterndrive]

Re: Disassembly of '78 OMC 800 Bearing Housing

factory manual has about 15 steps on 2 or 3 pages detailing preload measurement, special tools required to press and set bearings up in the brg hsg., measure rolling torque etc. A couple more pages on setting up the bearing hsg into the upper and shimming it.
Probably cheaper to take it to a pro than buy all the tooling.

 

[dhughes214]

Re: Disassembly of '78 OMC 800 Bearing Housing

My pops probably . Has all the tools. Hes got a drill press and all the bearing installers. Also has the tools to measure torque. Maybe i'll look into a factory manual. Thanks howard.

 

[Nivekt]

Re: Disassembly of '78 OMC 800 Bearing Housing

Howard is talking about OMC specific tools. These are not standardized tools. Very rare and I have only ever seen them on Ebay for purchase. Im sure there are work-arounds. Hopefully someone will chime in.

 

[Howard Sterndrive]

Re: Disassembly of '78 OMC 800 Bearing Housing

yeah if someone is good with gears and bearings he can probably set it up without factory tools. My analogy is if you can set up a truck differential (rear end) or similar powertrain components with tapered roller bearings, you can probably just use rolling torque, machinists blue and trial and error with a big bunch of shims.

 

[dhughes214]

Re: Disassembly of '78 OMC 800 Bearing Housing

My father has set up differentials before. Hes been out of town. So we havent been able to work on it. And he'll probably know theb answer to this, but i'll ask you guys anyways, can I not just put in the same thickness shims and assume it will all line up?

 

[Howard Sterndrive]

Re: Disassembly of '78 OMC 800 Bearing Housing

because the whole point of shims is to account for tolerance +/- between housings, gears and bearings.
If you divorce and remarry any of the above, you need to do the complete setup.
Cast aluminum is not a super precise material and the factory machines them within a fairly lenient spec range ("ballpark").
The assemblers then shimmed them to proper tooth contact and load using OMC fixtures and gauges as described in the manual.

It's all pretty straightforward, but if you get it wrong, the whole thing grenades first outing.

OMC, Mercruiser and others worked in volume, so they made foolproof fixtures instead of relying on generic precision measuring tools.

 

[dhughes214]

Re: Disassembly of '78 OMC 800 Bearing Housing

Oh ok. That makes sense. Hopefully this weekend we'll take a crack at it. If we do chicken out, there is a marine shop around here that will work on these old OMC outdrives. For someone that has all the necessarry tools is it a fairly quick job? If we dont want to attempt it we may call them for a quote.