OMC 800 Swap... question about upper unit *Video added*

[Andy4802]

So i'm well into this outdrive swap... initially I thought the lower unit was bad. I have a good lower with a good cable in it that I was going to swap in. I also have a full upper/lower assembly with a bad cable in it that I can use if needed but i'd need to swap over the good cable

What I wanted to do was swap in the good lower since it already had the good cable on it and call it done. So I dropped the old lower. Started up the boat and checked the upper input shaft and it was spinning which to me should have confirmed that the problem was with the lower. THEN, just for the heck of it, I shifted the cables manually on the lower I just removed and it seems to shift fine now... prop spins with shaft when in gear

I shut the boat off, disconnected the battery and stuck a couple fingers into the upper input shaft (don't know if that's the right name for it but im talking about the part that the splined lower shaft slips into (in the upper assembly). Anyway the upper input shaft has a lot of play in it... I can wiggle it back and forth about an 1/8th of an inch in any direction. Should this part have any play in it at all??? To me the bearing should keep it perfectly straight, no?

Here's the video OMC800-001 - YouTube

So now i'm thinking I have a bad upper and I should use my full upper/lower assembly, but then I have to get into a cable swap which looks like a pain in the butt...

what do you guys think?

 

[Boomyal]

Re: OMC 800 Swap... question about upper unit *Video added*

Nice vid Andy. I am sure that there should be no slop on that waterpump shaft, but then I am not sure. I know that you have lots of extra bits and pieces there but I would be remiss to just slap one on and hope it works and holds up.

It would be my preference to have that upper looked at and brought back up to spec. That way you will know what exactly you have and have some confidence that it will hold up instead of having to go thru this all over in a short period of time. That water pump shaft is a known wear part and could also be an issue in your other drive.

In addition to that, I would only take a minute to continue removing that upper from the intermediate housing.

 

[Nivekt]

Re: OMC 800 Swap... question about upper unit *Video added*

Last time I tore apart my upper I dont remember that much play in the shaft. More importantly, when I rebuilt it, I certainly dont recall ever wiggling things around to see how much play there was. Ive looked over my exploded parts diagrams as well as my own personal photos of my rebuild and dont see where there is a point at which that much play should be a normal observance. All parts should fit together very snugly, especially if greased properly. Im thinking you have a worn shaft. Time for a rebuild of that upper. Tear it apart and post up some pictures/video. Be mindful of your shims so that you dont have to re-shim the drive.

 

[Howard Sterndrive]

Re: OMC 800 Swap... question about upper unit *Video added*

I suspect that shaft wobble says more about the condition of your impeller than anything else. If you have an old worn impeller with vanes that are no longer pliable and have taken a set, it'll wobble around. Or that w/p shaft you are wobbling could be broken - you'll need to take the impeller out and have a look.

I can't follow as to what the original problem was, but if propulsion was lost - that w/p shaft could be broken or splines stripped explaining the excess wobble- they're around $150 and common failure point if impellers aren't serviced every 3 to 5 years with a good marine grease applied to the upper splines.

 

[Andy4802]

Re: OMC 800 Swap... question about upper unit *Video added*

So decided to swap the upper as well as the lower... it went very well, in fact it was a lot easier than I was anticipating to get the assembly bolted back onto the intermediate.
Good news is, perfect smooth flawless shifting, no grinding and no weird noises, forward and reverse are perfect... the bad news is that there's no water passing through the unit at all.
*sigh* I'll pull it back out this week and replace the impeller... hopefully that will fix it.
Boomyal I agree about a complete rebuild of at least the upper but time and budget don't allow it at the moment... the good news with all the spare parts I have now that I will have one that I can rebuild or have rebuilt when budget allows while the replacement is still on the boat.

Anyone have a good step by step for impeller replacement? I'm planning on buying the manual but I wouldn't mind getting started tomorrow if I can...

 

[Boomyal]

Re: OMC 800 Swap... question about upper unit *Video added*

......*sigh* I'll pull it back out this week and replace the impeller... hopefully that will fix it.....

Exactly my prediction. Going after the impeller in the replacement drive will put you in the exact same spot that you would have been, fixing that possibly broken/wiggling water pump shaft.

 

[Andy4802]

Re: OMC 800 Swap... question about upper unit *Video added*

Does the lower need to be submerged in order to circulate water or should muffs work? My muffs are just the cheap ones that feed from one side.

 

[Howard Sterndrive]

Re: OMC 800 Swap... question about upper unit *Video added*

muffs always work well on my 800 series. You can bend them to be tighter.
Or, you can put a handy flushing tee in the hose from the drive to the thermostat like this:

 

[Andy4802]

Re: OMC 800 Swap... question about upper unit *Video added*

wow found the problem! missing key on the water pump shaft! also, that little round clip is broken... so the shaft was just turning and turning and the impeller did nothing. Impeller is in excellent condition, shaft and all the bearings and gears are perfect too
I could make my own key easily but I don't think I can make that little round clip, I guess I wont be in the water this weekend. At least I figured it out

 

[Boomyal]

Re: OMC 800 Swap... question about upper unit *Video added*

Good on you Andy. We have nothing to fear but fear itself!:joyous:

Check the condition of those splines real good while you are in there. That shaft is a notorious wear point.

 

[Andy4802]

Re: OMC 800 Swap... question about upper unit *Video added*

Shaft looks good... I have a spare that's in worse condition so i'll use the one that's already in there. I also found a waterpump shaft key in my parts pile, all I need now is that darn clip!

 

[Andy4802]

Re: OMC 800 Swap... question about upper unit *Video added*

Does anyone know where I can buy that little round clip?

 

[Andy4802]

Re: OMC 800 Swap... question about upper unit *Video added*

Gents, thanks so much for your help foot is re-assembled and installed and working flawlessly ... smooth shifts and great water flow-through. For the missing clip, I made one out of a small spring that had the same diameter and the old clip... I snipped a round section out of it and presto, new clip... unfortunately its not stainless so I greased the heck out of it and I will inspect it every couple years when I regrease the impeller.
I'm off to a family function now so no time to test it on the water but tomorrow morning i'll get up early and install the prop, hook the cables up to the shifter and drop her in the lake
I am in your debt, cheers.