1985 omc 800 crapped out!

Ctjheiner · Jul 27, 2013

Hi everyone, I'm new to boating, never bought a boat before. So I picked up this '85 beach craft with a Chevy 305 and 800 out drive. So I found out when I got it home that the prop shaft was bent, the prop wobbled (should have checked that, but again I've never bought a boat). So, my friend said run it till it goes out. Took it out for the second time, ran good for about 2 hours then heard a bunch of clanging, banging, and a really bad vibration when in gear. So I limped it in. Spins freely by hand, really wobbles. My friends say lower unit is out.

So first of all, go ahead and let me have it for buying a boat without knowing anything about it (my wife sure hasn't let me forget it)

Second of all, what lower units will bolt up? My plan is to get it going to finish the season and rebuild mine this winter. So there's a couple boats with bad motors on Craigslist with omc's. both are '79's. will those lowers bolt up to my boat? Both have same motor as mine. Then there's a lower for sale off an '83 "hydro mechanical" shift. Is that one an option? Any help would be much appreciated.

fincastle · Jul 28, 2013

Re: 1985 omc 800 crapped out!

The '79 lower units should be hydro-mech shift and would require swapping out the shift cable and everything related. The '83 unit should be full mechanical unit and would work assuming the gear ratio is the same

jerryjerry05 · Jul 28, 2013

Re: 1985 omc 800 crapped out!

Not real sure about the 800 drives but, they have 2 different sizes of lowers.The bigger motors used a larger lower.
So make sure the one you get is from a 3.0.
Not positive about that but I'm sure someone will correct me if I'm wrong.
Oh yea,Welcome.
Fill out the profile,location? You might be close to someone who can help.
The parts crossover says the 83 isin't a match?? Not sure if thats true?
The lower is still available.
0983517 GEARCASE & BRG ASSY $1, 318.92

Boomyal · Jul 28, 2013

Re: 1985 omc 800 crapped out!

Ctjheiner said:
........So first of all, go ahead and let me have it for buying a boat without knowing anything about it (my wife sure hasn't let me forget it)........

Even more so than that, you should be spanked for continuing to run a boat with a known mechanical issue, ie, bent prop shaft! That probably could have been repaired without having damaged any other components......and yes, you should have at least sought out a knowledgeable friend or acquaintance when shopping for a boat.

As for outdrive lengths, starting 1979, OMC only made one length. That was the short one. Earlier electric shift drives came in high and low profile. They are not applicable to anything '79 or later.

Ctjheiner · Jul 28, 2013

Re: 1985 omc 800 crapped out!

Thanks guys for the replies and help. You're right boomyal, I shouldn't have taken it out. I'm not a mechanic by trade but fairly handy I do most of my own mechanic work on my vehicles and toys. So my first reaction to the bent shaft was fix it before it explodes, but that's what I get for listening to a friend instead of my instinct.

So the lower out of the '83 the guy said was hydro mechanical, but I don't trust his opinion, how do you tell? If I swap a lower from one of those '79's how much stuff do I need to swap to get the hydro mechanical shift to work? I also found another '79 with a 351 ford in it, would that lower bolt up to my boat which has the 305? I know the bellhousings would be different but would the lowers swap across?

You guys are great. I've had a pretty bummed out and stressful weekend with this boat, I'd really like to get it out a few more times.

Boomyal · Jul 28, 2013

Re: 1985 omc 800 crapped out!

I doubt the lower out of the '83 is a hydro-mechanical lower. Someone would have had to go thru a fair amount of work just to go backwards. Full mechanical drives, which is what you should have, came on in '82. That being said, here a picture of the full mechanical drive. Note the anode above the cavitation plate. A hydro-mechanical did not have this.

You also want to make sure that the lower that you are looking at is for an 800 not a 400. 400's may be a smaller case and for sure, the wrong gears.

Ctjheiner · Jul 28, 2013

Re: 1985 omc 800 crapped out!

I was trying to copy the picture in but it won't work. His doesn't have this anode. He said its an 83 but like I said I won't take his word for it. It's on Craigslist in easy idaho.

Ctjheiner · Jul 28, 2013

Re: 1985 omc 800 crapped out!

Sorry, dang phones. Meant East Idaho Craigslist. Is the anode just on that side or both sides?

Boomyal · Jul 28, 2013

Re: 1985 omc 800 crapped out!

Ctjheiner said:
Sorry, dang phones. Meant East Idaho Craigslist. Is the anode just on that side or both sides?

You can see it from both sides. There is no opening for an anode on a hydro-mechanical unit.

If this is the ad you are looking at, it is for a hydro-mechanical lower. The prop is also chewed up. I would not trust a drive like this without going thru it first. He claims he has the shift cable for it (it is different than the full mechanical) but I do not see it attached. You would also need the hydro-mechanical shift converter.

OMC 800 Lower Unit and parts

Ctjheiner · Jul 28, 2013

Re: 1985 omc 800 crapped out!

Yes that's the one. It does look hammered one of those '79's I mentioned was just gone through a year ago. So where would I find the shift converter and would it be worth it? How much do they run? Thanks a lot for your help

Boomyal · Jul 28, 2013

Re: 1985 omc 800 crapped out!

Are you sure your lower is absolute toast? I would not just buy a drive off of CL or Ebay and trust that you can install it and go. You'd probably be back in the same boat you are now (pun intended)

I would at least hold out for a full mechanical lower. They are superior to the hydro-mechanical and virtually the same as the later Cobra. Also you are set up for one instead of having to fiddle with something different. Also I would not trust that ad, especially as the guy told you the wrong year AND the fact that you have no idea what he has for the shift cable. It has been removed from the drive and would require being set back up and timed (that is if the cable and the shift housing are even good and complete.

Ctjheiner · Jul 28, 2013

Re: 1985 omc 800 crapped out!

That's true. I was just looking for a less expensive option to get me back on the lake this summer then rebuild mine this winter. I'll keep my eye out for a mechanical shift and get mine into the local omc guru.

I really appreciate your help, that's more info then I could find on the Internet in 3 days. You guys are great!!

Boomyal · Jul 28, 2013

Re: 1985 omc 800 crapped out!

Ctjheiner said:
That's true. I was just looking for a less expensive option to get me back on the lake this summer then rebuild mine this winter. I'll keep my eye out for a mechanical shift and get mine into the local omc guru.

I really appreciate your help, that's more info then I could find on the Internet in 3 days. You guys are great!!

Too bad you were not closer to Portland. We have a great old time OMC guru on the Columbia River.

Ctjheiner · Jul 28, 2013

Re: 1985 omc 800 crapped out!

I've been referred to a guy here in Pocatello idaho, everyone says he's good, we'll find out.

I actually have thought about moving to Portland in the past, I think it's a pretty place. Maybe someday. I really do appreciate your help with this, next time I'll do the research before I buy.

Ctjheiner · Jul 28, 2013

Re: 1985 omc 800 crapped out!

One more quick question. Is there any difference in the lower units on a 351 ford and a 305 Chevy?

Boomyal · Jul 28, 2013

Re: 1985 omc 800 crapped out!

Ctjheiner said:
One more quick question. Is there any difference in the lower units on a 351 ford and a 305 Chevy?

Not entirely sure Ct, but for my 302 SBF, the Hydro Mechanical was a 1.50:1. I would assume that the 351w would have been similar. I am not sure what gear ratios OMC might have used for other small block variations.

Boomyal · Jul 28, 2013

Re: 1985 omc 800 crapped out!

Ctjheiner said:
....... next time I'll do the research before I buy.....

Unfortunately some of the research you might have done would have steered you away from the stringer drive. With reduced values of boats with Stringers, you might have been lead astray. IMHO, even with some of the drawbacks, a stringer is simpler, less complex and has many characteristics that blow the 'black anchors' ie, Mercs, out of the water. Undoubtedly, there may be a different set of understandings that you need to work on them but in the end, where would you be with a Merc outdrive with a fubar'd lower unit? That is not even to mention all of the other Rube Goldberg complexities of the Merc.

Get it fixed, learn it's requirements and have fun. Above all, DO NOT use the tilt as a trim.

btw, my Hydro-mechanical drive is now 24 years old. It has hundreds of hours on it pulling skiers and multiple skiers. Some salt water use but mostly fresh water. It has never failed me. I had it torn down for inspection back in 2006 on general principle. I had it out of the boat to redo floors and stringers. It had been working fine but there were some worn splined shafts that need replacing.

Go and read all the frustration on the Merc drive forum for units that are not near as old.

Ctjheiner · Jul 28, 2013

Re: 1985 omc 800 crapped out!

You know, you are probably right. I probably would have steered away from the OMC in the little research I would have done before buying. But in the research I have done after buying, I've found good and bad reviews of the OMC and of the Mercs. But I am leaning more toward the OMC's in that research. Don't get my wife started on this little trait of mine, but I'm a real sucker for the underdog. If it's popular, I'm not a fan. So the overall un-popularity of the OMC has drawn me to it if that makes sense. And there are quite a few advantages to the OMC that I really like.

Thanks again for all your help, I'll be around with more questions, and hopefully some answers for other guys in my boat (pun intended)

Boomyal · Jul 29, 2013

Re: 1985 omc 800 crapped out!

Boomyal said:
.......btw, my Hydro-mechanical drive is now 24 years old..........

CORRECTION: make that 34 years old!

1985 omc 800 crapped out!

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