1978 OMC 120 / 400 Stringer Tilt Motor replacement

[mattsmall1972]

I need to replace the tilt motor on my 1978 OMC 120 / 400 Stringer drive. It is possible to do this without removing the entire stern drive? I know that I get get to the two bolts that hold the motor in, but it's the reinstallation that I'm concerned about.<br /><br />Thank you.

 

[Boatist]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

No need to remove the outdrive at all. Are you sure the motor is the problem? Could also be a fuse, Solenoid, Poor conection, Clutch pack, or grease to the tilt pins.

 

[mattsmall1972]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

Thanks, I'm glad I don't have to remove that. I have already checked the electrical connections, those are fine. Tell me about the clutch pack and grease to the tilt pins. the boat has been sitting for about 4 years. I have the manuals, but I didn't know to check for the grease and clutch pins.

 

[KaGee]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

You definetly need to lubricate the pivot pivot pins. Zerk fittings are located underneath the two side bumpers. The bumpers pop off, but the drive must me all the way down to do so.<br /><br />The tilt gearbox, which contains the clutch pak, is filled with oil. It needs to be drained and refilled. Originally it called for motor oil, but I would use gear oil in that too.<br /><br />Location and maintenance of all this should be in the manual.

 

[fendersfender]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

The main reason for those motors going bad is usually water intrusion, usually the tilt gearbox will leak and then water follows the path to the motor, so when you change oil in tilt mechanism, make sure there is no water present. If there is water, go buy yourself a manual and a seal kit.

 

[mattsmall1972]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

OK, so I've been playing with the new motor I got on ebay today. I had a hard time figuring out that each connection on the motor represents a direction. Once I figured that out, I definitely determined that my electrics were good.<br /><br />So I opened the drain plug on the clutch and found that a few drops of milky oil came out. <br />I drained the whole thing and refilled it with trim/tilt oil. I tried again to run the tilt but no dice. The motor makes the attempt, but nothing happens. <br /><br />I've decided to completely rebuild the tilt mechanism now. I have to wait for my stern drive holder arrives before I can move on. Now I have to order a new clutch pack and the trunnion bearing stuff as well...<br /><br />I'll keep you posted.

 

[Boomyal]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

Don't get ahead of yourself Matt. I'm sure there is a better way to determine the cause of the problem. The clutch pack is only there to break loose in the event of an outdrive impact, otherwize it acts like a one piece unit. <br /><br />I would give you a scenario for testing but I gots to go to a Boy Scout Eagle Court of Honor.

 

[mattsmall1972]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

OK, I'm willing to wait to try other things. I have the new motor that I haven't installed yet. One other thing is I have not greased the pivot pins. <br /><br />One question about that - should the motor be able to move up and down if I try to move it? If I remove the motor will it move?<br /><br />Thanks for all your help.

 

[fendersfender]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

nope, its designed to only move by the motor

 

[Boomyal]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

Matt, I didn't realize that you had not tried the new motor yet. I was trying to stop you from rebuiding the clutch pack. Now that you have drained and refilled the gear box I would install the new motor and see how it works.<br /><br />Do you have the flanged motor or the thru bolt motor? They changed them in 77 or 78, I don't remember which.<br /><br />If it works, there are still some things you'll want to do. Let me know.

 

[Boatist]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

If you take the 3 bolts out of the big tilt gear you can take the big gear off. At this point you can manually raise the outdrive. The out drive is heavy but you can tell if it's just the weight or hard to pivot. If it is stiff and hard to raise then take two rubber stops off of the upper outdrive. Put some blocks under the outdrive to support the weight of the drive. Remove the two cap bolts on each side and pull the outdrive pivot pins away from the boat about 1 inch. Make sure you watch how sleaves over the pivot pins come off. Clean all the old grease off and recoat all the way around with OMC triple guard greese. Reinstall caps. The put a little extra greese in at the zert fittings to make sure there open.<br /><br />While you got the big gear off try to raise and lower from the switch the small gear should turn in both directions. If it does not I would remove the small gear and the the clutch pack cover and push the clutch pack out. Again try the motor. The motor and worm gear should turn if the motor is good and your getting 12 volts to the motor leads. By this time you should know where the problem lies.<br /><br />If you have 12 volts to the motor in both directions them both 50 amp fuses are good and the solenoids are good. if it does not turn then it is the motor or the worm shaft if froze up from water.<br /><br />Good Luck

 

[mattsmall1972]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

Thanks, this is terrific information. I was wondering if it was a good idea to remove the big gear.<br /><br />I don't know if I have a flanged motoro or a bolt-through, how would I tell?<br /><br />I know my electrics are good because my new motor runs fine when attached to the connector. I tested that there is voltage at the connector as well. And I've searched high and low aand there just are not any 50 amp fuses back near my motor. I've examined the whole wiring harness and can't find these things. It's crazy that everyone talks about them and I clearly don't have any. <br /><br />I'm looking forward to getting hom tonight to try this!<br /><br />Thanks.

 

[KaGee]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

So I opened the drain plug on the clutch and found that a few drops of milky oil came out. <br />I drained the whole thing and refilled it with trim/tilt oil.

Ummmm.... hate to tell you this, but you will have to drain it and and refill with gear oil.<br />You essentially put in hydralic fluid.

 

[mattsmall1972]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

OK, I'll try some motor oil instead. Thanks for catching that.

 

[Boomyal]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

Originally posted by mattsmall1972:<br /> I don't know if I have a flanged motoro or a bolt-through, how would I tell?

Thru bolt (color not stock)<br />

<br /><br />Flange Type<br />

 

[mattsmall1972]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

Hi guys, I've got some more info...<br /><br />1) I have a bolt-through motor. I can't fathom how it's supposed to come off without removing the intermediate housing. The bolts are in such an awful position located behind the bell housing area that I can't reach them in any meaningful way to remove them. I'll try again, but if it's got to come off, it will probably be when I remove the intermediate housing.<br /><br />2) I managed to get the tilt quadrant off and move the motor into a tilted position. The motor is not moving freely at all. I did manage to get some grease into the zert fittings, but only one of them seemed to take the grease. It's going to require some work to get the motor moving freely. I will follow the steps Boatist suggested.<br /><br />3) The gear does not move freely at all. I removed the snap ring and the gear wants to come off, but the clutch and housing will not come out. I pounded it with a hammer (firm but not hard) but no dice. Am I supposed to remove something else? I see in my manual that the worm gear area might need to come out in order to allow the clutch to be removed, but I can't see how to get it to come out (that area behind the triangle-shaped piece of metal). <br /><br />Ok guys, what next?

 

[KaGee]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

I believe you found your real problem... the pivots need a good cleaning and lubrication.<br /><br />I used a 1/4" drive ratchet with extention and flex joint to remove my drive motor.

 

[Boomyal]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

I believe that I get my tilt motor out with a box end of a combination wrench. Even if the TM is not your primary problem, at minimum you will want to inspect and clean it. Inspect the brushes and the commutator.

 

[mattsmall1972]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

OK, I got the motor off. It is terrifically dirty, but I've already got a new one. I think this one is probably good even though it's rusty on the inside.<br /><br />I'm still having problems removing the clutch pack. I see in my manual that the worm gear should be wiggled to remove everything, but this just doesn't want to come out. Anybody have any suggestions?

 

[mattsmall1972]

Re: 1978 OMC 120 / 400 Stringer Tilt Motor replacement

One more update for the evening:<br /><br />I managed to get the clutch pack cover off. I was stuck really hard onto the shaft. The tilt mechanism is rusty and there's sludge all through the area. I know now that everything must come out to clean it properly.<br /><br />One odd thing is that the tilt gear just *WILL NOT* come off the shaft. The manual mentions a plastic plug on the end of the shaft, but I must be blind because I can't see it. The shaft seems as though it's bigger on the very end, because the gear slides all the way to the end until it reaches the side of the shaft, then it stops. I do think there is something blocking the gear but I haven't figured it out yet.<br /><br />Aside from that, the clutch housing gear seems firmly stuck in there. I'm hoping that once I figure out how to get the worm gear out of there, I will be able to remove the clutch housing.<br /><br />One final thing - the hammer-blow coupling - it is necessary to remove this to get the work gear out?<br /><br />Thanks for all of your help.