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Newbie needs help with OMC 800 1978 series 305 sterndrive

Shado

Shado

New member
Hi everyone,

My name is Bob and I recently purchased a 1978 IMP Aztec with a OMC 225 305 powerplant, and a 800 sterndrive.

I have owned several outboards before, but I never owned a inboard/outboard until now and so a lot of this boat is new to me. I am very good mechanically, and have built several racing engines for my motorcycles.

I got the OMC 400/800 manual with the boat (lucky me) and so I have pretty good documentation for whatever is to come.

I started up the engine when I got the boat home using the ear muffs, and the engine sounded smooth and strong. The stern drive moved up and down without issue and the steering mechanism worked perfectly. and I thought I was good to go. I went ahead and gutted the boat, and reupholstered and carpeted the interior. I made schematics of the wiring while the boat was "*****" for future reference, and verified all the gauges, and electronics on board functioned.

I finally took the boat out yesterday to see if it would float :) - it did.

BUT...

Once I started her up in the water, I put her into reverse to back away from the boat ramp and cruise to the dock where I had my granddaughters waiting to join me on the inaugural cruise.

...nothing happened...

The shifter moved smoothly into position but there was no thrust. Hmmmm...

I cranked up the trolling motor and backed the boat to deeper water so as not to run aground and cause any prop damage. Once I was in deeper water, I put her into forward and the same thing happened.... No thrust.

The guy I brought the boat from had told me that he used it this year and it had no problems. He was moving to Costa Rico and could not take it and so thats how I came to purchase it from him. He is now no longer here and I am feeling a little ticked off that he lied to me.

But I digress...

I used the trolling motor to putter around the lake so as not to dissapoint my grandchildren, then loaded her back up on the trailer and headed home.

I got home and immediately started searching the web for whatever info I could find on the OMC 800 stern drives to see if I could find a hopefully easy fix.

After much study, I find myself no more educated than when I started. I am humbly asking for some help in diagnosing and repairing whatever problem is plaging my boat.

I have turned the key on and put the boat into forward gear. When I try to turn the prop in this state, it will not move forwards or backwards. When in neutral, the prop turns freely. When in reverse, the prop turns 1 click at a time in one direction, and not at all in the other.

I checked the pulse module for the electrical shift assist and it is functioning correctly. I replaced the prop with the spare that came with the boat with no change to the problem.

The motor does not overheat so I am pretty sure the impeller is working.

The ball gears are engaged and turning when the engine is running and do not have too much wear on them (I raised the engine a little while it was running to verify this, then tilted it back down)

At this point I am afraid that I am going to find out that I have broken gears or some other equally bad mechanical issues with the lower unit.

I would appreciate it if someone wiser than myself could take me under wing and help me to diagnose and repair my drive so I can enjoy at least 1 more outing this year before winter hits.

Thanks for listening to my tale of woe. I await the sage willing to accept a new apprentice. :)

Bob
 
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Re: Newbie needs help with OMC 800 series sterndrive

OK, If no one can help me with my original question, is anyone here able to tell me if there is anything I need to look out for if I remove the lower unit and disassemble to see if anything obvious is broken? Do I just remove the bottom bolts and remove, or are there springs, or anything else that might fall out I should be careful of. Does the lower unit seem like the most likely area to start in or should I be looking at the upper unit instead? Thanks. Bob
 
Re: Newbie needs help with OMC 800 series sterndrive

I am surprised i didn't see your post last night, but it has been crazy around here. You have a electric shift drive?
 
Re: Newbie needs help with OMC 800 series sterndrive

Yes sir. I have a 1978 Aztec with a OMC 225 engine, and OMC 800 series sterndrive. It has been fitted with an electronic shift assist kit (kit # 982497)
 
Re: Newbie needs help with OMC 800 series sterndrive

Ok lets together do some trouble shooting. Put the boat in the water, start it, remove the long hose off that comes in from the transom and ether goes to a heat exchanger or the t-stat, hold it straight up and see how high it shoots and quick shut off the motor.

If you have good water coming into the motor then it aint the shaft splines or the ball gears or the coupler. See how easy that was to rule those out. You need to do it when the boat is in the water or the drive submerged. If you run it on a garden hose the force of the water could mess up the test capiche?

Now grasshopper if the water is good to the motor then me thinks it not shifting in the drive, could be a bunch of different reasons, lets first find out if you got good water to the motor.
 
Re: Newbie needs help with OMC 800 series sterndrive

OK, made a 70 mile roundtrip to Cochiti lake and did as you asked. Plenty of water - about a 6 to 8 ft stream. I think I am going to make a tub for any future "in water" testing. That's a lot of time, gas, and work for a quick 30 second test. ;)
 
Re: Newbie needs help with OMC 800 series sterndrive

" 6 to 8 ft stream" !!!!! Holy cow when I check Cobras I'm only for approx 4 inches at the input hose removed from the t-stat.
 
Re: Newbie needs help with OMC 800 series sterndrive

ZSorry, typo - it should have been 6 to 8 in stream, not ft. "blushing" I am typing to quick. I pulled the hose from the thermostat at the rear of the engine, right before the intermediate case.
 
Re: Newbie needs help with OMC 800 series sterndrive

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These are pics of where I pulled hose from. I just redid everything in the yard in a waterbath with different results. Now water is only coming out from the port where I removed the hose, not the hose itself.

Here is pic of submerged drive unit. I hope it is deep enough in the water for this test. All the inlet ports are covered.

DSCN3348Large.jpg
 
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Re: Newbie needs help with OMC 800 series sterndrive

I can't express in words how happy i am you put up that pic of the drive. And when i'm done typing your gonna be happy also.

First you have a latter model drive then the year would suggest you first put up in your op.

You have the last of the stringer models and the best of the series. You have a full mechanical shift model grasshopper.

Your problem is not related in anyway to the esa.

Your problem is related to the ether the shift converter and or the cable connection of the throttle cable to the shift converter, or the lower cable connected to the shift converter.

So when you do go back to the boat observe the shift converter when you shift, doesnt matter if it's running or not.

When you shift the thorttle cable moves the converter, the lower cable will move also if connected.

Now lets say all the cables are hooked correctly, and it's shifting correctly then the only other problem could be the lower shift cable hooked to the shift bar in the lower unit.

I will include a link to adjust the NOMINAL SHIFT PROCEDURE. the link will also include other useful info, at the end of this post.

To access the lower unit shift cable to shift bar you have to drop the exhaust housing, and lower unit all in one piece.

Here is the post i made on dropping the lower to access the water pump same as accessing the shift cable.

No need to remove the entire drive.

Have a table or a large cooler or chair ready on the starboard side.

On a trailer lower the bow as far as it will go, and raise the drive 1/2 the way up.

Remove the very top bolts, and the exhaust and the lower will come down. place it on the table and tie it to the swim platform. be careful of the cable don't pull on it plenty of play in the cable.

remove the 4 bolts facing u in the upper drive from the bottom and the whole waterpump and shaft will come out. you could raise the drive a little more to make it easy, i sit on a milk crate when i pull the pump.

Then you can access the shift to bar connection a pin will have to be removed. However if the connection is good there, then sad to say the shift dog is suspect.

Before we go there lets see if the shift converter os hooked up correctly.

By the way when you had it running and in the water and you shifted did you feel and hear the shift, it's like a clunk it is unmistakable.

Side note the motor should idle around 600 in gear on the water warm motor. But not in gear then around 700.

Good news you have the best of the stringer drives, bad news it's not shifting cause of a lower cable, throttle cable, or the throttle shift cable not hooked up to the throttle.

Start at the throttle cable make sure it's moving the shift converter if not your lucky it's that.

Maybe the throttle cable nut fell off the back of the throttle or something like that.

Post back we will go from there. Sorry about your long trip that i can;t help but this problem of yours with the boat i can and will help you.

help center omc
 
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Re: Newbie needs help with OMC 800 series sterndrive

Even though you do have the water inlet submerged personally I don't think that is high enough and the pump will never prime or if it loses it's prime it's hard to get it back. I know on Cobra's almost the entire drive needs to be under the water. I don't think you have any water issue's though based on your earlier results. If your gonna run it at home either get a bigger container or just use the muffs.....now back to the Chief to fix your shift problems!
 
Re: Newbie needs help with OMC 800 series sterndrive

OK, just checked the cables as suggested. The shifter moves into gear very smoothly without any clunking or obvious transition. The lower cable looks like it is moving as the sheathing flexes when I move into forward or reverse. As I said in my first post, when it is in forward, the prop will not turn, in neutral the prop spins freely, and in reverse it will not turn. A few days ago when I tried this, reverse would turn in one direction in clicks and not the other, but now it will not turn at all when in reverse. I will start to disassemble the unit in the morning as I will be off. I will post pictures as I progress.

Let me take this oportunity to thank you for your time and expertise. I really appreciate it andd will try to pay it forward to others in the future.

Pics below are of the shift unit in forward, neutral and reverse.

DSCN3350Large.jpgDSCN3351Large.jpgDSCN3349Large.jpg
 
Re: Newbie needs help with OMC 800 series sterndrive

All the shifting is done in the lower unit. I have the same series drive you have, mines a 400 is the only difference and there is no difference except the upper gears.

You tried the nominal adjustment in the link i sent you ? I am hoping it's the adjustment for your sake grasshopper.

Then the problem is in the lower. I already told you how to drop the lower while your at it i would pull the water pump in the upper you will see all the gears and how it works shafts and all, you will need the knowledge latter.

The manual will tell you how to take apart the lower. If yes might pay for you to buy the reseal kit, but thats for latter lets find the problem.
 
Re: Newbie needs help with OMC 800 series sterndrive

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I used my shifter manual and checked the nominal neutral position. It is set up perfectly, with the difference between forward and reverse at 2 1/2 inches. I adjusted the shift cable tension as per the manual. I verified the ignition pulse switch operation and then and retried putting the system into forward and reverse with thee engine running. No change, prop will not turn in forward or reverse. I put pics of shifter positions to verify they are correct. I will now go ahead and remove the lower.

DSCN3352Large.jpg
 
Re: Newbie needs help with OMC 800 series sterndrive

Pulled the lower unit. Pics below
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DSCN3361Large.jpg


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DSCN3363Large.jpg

Cable is firmly attached. I did not remove the pin yet as I wanted to make sure thats what you wanted me to do next. Waiting for orders.
 
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Re: Newbie needs help with OMC 800 series sterndrive

By the way, is this right? It almost looks to me like the shaft is snapped off. My drawing shows a spline at the top of this shaft, but I don't see one.
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Re: Newbie needs help with OMC 800 series sterndrive

yep keep going, you will need a long nose pliers. I forget it's ether forward or reverse makes it a little easier. The throttle that is. When it's off have someone move the throttle make sure the cable is moving to the lower bar.

I have to say this where you live is just gorgous i was there on a 6 week trip to all the national parks i took with my family, and when we hit your town we stayed at the Embassy suites and when i opened the blinds in the morning the sky was filled with hot air colorful ballons.

And the brazillian steak house just great.

We still talk about your town, will be back one day.
 
Re: Newbie needs help with OMC 800 series sterndrive

Wait a sec. bear with me it is just f---ing crazy here my daughter is getting married and is moving into a new apt. my younger son has the first hs football game tonight.

I just looked at the pics again. Something is wrong where are the splines that line up with the upper splines. I swear it looks like you snapped the upper shaft and it's stuck on the lower gearcase verticle shaft.

What book you working out of i can point you to the right page if it's a seloc #3400 in the upper right hand corner to explain better.
 
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Re: Newbie needs help with OMC 800 series sterndrive

Pic's tell it all...

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At least all I have to do is superglue it back together. :(

buzzkill!!!
 
Re: Newbie needs help with OMC 800 series sterndrive

Working out of the OMC 400/800 series service manual

DSCN3367Large.jpg


You must be talking about Tucano's Brazilian restaurant. It is my favorite in Albuquerque - it's a carnivore's delight!

If you ever get back to Albuquerque, email me and I will treat you to dinner there as my thanks for your assistance. [email protected]

I am now looking online to order the spline which I am sure is crafted from pure unobtanium and will have a pricetag to reflect that fact.
 
Re: Newbie needs help with OMC 800 series sterndrive

I have to leave in about 15 minutes to go to the game. More i think about it it makes sense the upper water pump shaft is turning giving you water to the drive and motor , but the lower unit verticle shaft is not turning so the pinion is not turning and thusly the drive might shift but no power to the lower capiche ?

Don't remove the pin yet might not have to. You did make a double post yes the shaft snapped off.

Ok can you get the shaft off the lower splines. The whole problem in the upper.

Sit on a milk crate remove the 4 bolts that hold on the water pump, the water pump, 2 shafts and gear with the bearing housing should come out all in one piece.

Split the upper shafts is the bearing carrier shaft still good?

Repeat do not remove the pin leave the lower alone.

There is a guy i bought the shafts from 69 bucks apiece on ebay. Do a search. Don't buy it yet till you post the link and we know what shafts you need and what else you might need there is a place you can buy it all in one kit, with the shafts rebuild kit for the upper and water pump kit all in on box cheaper then anywhere, but i can't look it up on my puter this second and i will pm you the link not in the open forum.

I should be back home around 10 maybe ealier, east coast time. Get the water pump out. with the shaft, drain the upper first.
 
Re: Newbie needs help with OMC 800 series sterndrive

Yep, its the lower verticle shaft. I have been trying to remove it but I cannot get the unit to budge. Screws removed, and nothing works to get it out so far.
 
Re: Newbie needs help with OMC 800 series sterndrive

screw that holds the screen in removed, the very large c clamp removed. The one that you need the very long tarauq pliers or very long needle nose with the ends ground down.

Where you up to ? It's a mother f believe me i know.

I got to say this you are the easiest one i ever taught or guided thru this chit in years.

My hat off to you sir.
 
Re: Newbie needs help with OMC 800 series sterndrive

I will get back to it during lunch tomorrow. Checked the manual and apparently I have to remove the prop shaft bearing assembly and a few other things to get it out. My workweek starts tomorrow so it will be the afternoon before I get home and get back to dis assembly of the shaft. I have done some searches online and so far the best price I found is around $200.00 for a replacement. I am assuming the pinon gears etc. will probably still be good as the shaft snapped cleanly. I guess I will know for sure once I complete the removal. Thanks again, and I will get back with results tomorrow. Have a good night.
Bob
 
Re: Newbie needs help with OMC 800 series sterndrive

This looks like a really good deal. Need new lower end for my '78 OMC 800. Boat doc says I need (want) Mechanical instead of Hydro-mechanical. Is this what I need?
 
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