OMC 800 Tilt - Need help!

MikeCC

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Feb 27, 2022
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I'm trying to revive a boat with a 1985 OMC 800. Before it was put away, about 12 years ago, I had trouble with the tilt. Almost certain it was the motor. Sitting for so long didn't help with the other components. So here is what I have done so far.....replaced the motor with a Sierra brand, cleaned the contacts at the solenoids, brand new battery, replaced the clutch pack and worm ring gear and lubed it, pulled out the shaft and worm gear and cleaned it up, cleaned up the quadrant gear and spur gear. Trunnions are greased as well. The drive will go down but still does not want to go up. I will get a clunk sound and maybe a few mm of movement, occasionally an inch.

With the quadrant gear removed, the clutch shaft spins freely in both directions. I know I'm getting at least 12 volts to the solenoids, but is it possible for the voltage to drop within the solenoids? The only component I haven't really checked is the hammer blow, but I assume since everything is spinning, that there shouldn't be a problem with it. I don't know what else I can do to get this thing working right. Are the Sierra motors known to be too weak to lift the drive? It feels like there is plenty of power there and that something else is binding it, but I feel like I've got everything together properly and lubed up.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Jul 23, 2011
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49,569
sitting for 12 years, did you clean every cable connection? what is battery voltage? what voltage are you measuring at the tilt motor when you are opperating it? do you have water in the clutch packs?
 

racerone

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Dec 28, 2013
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37,826
Loosen the 4 bolts on the intermediate bracket pivot bearings.----Test.-----Perhaps jammed with corrosion.
 

southkogs

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Might test your tilt switch too ... make sure the "up" selection is working properly.
 

racerone

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Dec 28, 2013
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It takes a lot more current for UP.------Motor may have thermal overload protection.
 

MikeCC

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Feb 27, 2022
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I cleaned and greased the trunnions. The drive lifts easily by hand.

I believe the switch is ok, because the motor and gears spin freely without the drive attached.

The thermal overload can be an issue. I've noticed if I try repeatedly, it stops trying to turn. I'm wondering if maybe my new motor is just not strong enough to lift the drive.
 

kenny nunez

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Jun 20, 2017
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3,290
Remove the tilt motor and the hammer blow coupling, there should be a plastic thrust washer on both sides of the coupling to keep it centered and not drag against the housing. They can be substituted with a thin steel washer with a little grease if you do not have the plastic ones. If the tilt shaft is removed while the motor is mounted the rear washer falls down and no longer centers the coupling. After doing this with the quadrant gear removed run the tilt motor in both directions.

You said the trunnions are greased, with the quadrant gear removed can the drive be raised by hand with no resistance?
Put a volt meter on the battery feed side of the tilt solenoid and watch if there is a voltage drop when the tilt switch is engaged to raise the drive.
Your model has large Buss type fuses which will also cause your problem. They are 50 amp fuses, replace them with new ones.
 

MikeCC

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Feb 27, 2022
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I'll have to see if I can reach the motor from inside. When I replaced it, I had the transom seal off. I didn't pull the shaft out, just the worm gear. But could it be possible the thrust washers could be worn out, causing the hammer blow coupling to drag?

The outdrive does go up and down easily by hand with the quadrant removed.

I haven't checked for voltage drop. Is it possible for the solenoids to be functional, but cause a drop in voltage output? I'm getting at least 12V in, but not sure what is going out.

I did pull the Buss fuses and they looked good, but I sanded the contact points anyway, just to be sure they made a good connection.
 

kenny nunez

Captain
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Jun 20, 2017
Messages
3,290
If the Tilt shaft has not been removed then the thrust washer should still be in place.
I have had those fuses look good and show continuity but not be able to run the tilt motor.
 
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