OMC Stringer 400 problem

[Rich B.]

This forum looks like a great place to get information, so I joined.

I recently acquired a 1980 16' runabout boat that has a GM 120 HP 4 cylinder and the OMC Stringer 400. Well the issue that I am having is the out drive will raise enough to break the seal to the intermediate exhaust housing while driving. You know this has happened when you hear the volume of the exhaust get louder and you start loosing RPM's on top end. I have to stop and lower the drive then off I go again. This consistently happens when taking off full throttle i.e. pulling a skier, etc. Is the tilt clutch assembly responsible to hold the out drive in the down position, and only allow upward movement in the event the lower unit hit something in the water while under power? I am wondering if the clutches need replaced or is there an area I should be looking at to fix the issue?

 

[Howard Sterndrive]

Is the tilt clutch assembly responsible to hold the out drive in the down position, and only allow upward movement in the event the lower unit hit something in the water while under power?

you got it.
your problem is a slipping tilt clutch. Later ones had a tension adjustment (you could externally adjust friction with allen key), but I think that came after 1980.

 

[southkogs]

Welcome aboard Rich:

Are you sure something isn't happening with the trim? With the drive tilted full down, the pressure of the thrust of the prop should hold it in place - I've been out once without my quadrant gear in, and it did what it was supposed to.

If your transom boot is opening up ... you've got bigger problems than a clutch pack. Got photos?

 

[superbenk]

southkogs is right, the force of the propulsion would be pushing the drive into the transom, not away from it. Reverse would be a different story, obviously.

 

[Rich B.]

you got it.
your problem is a slipping tilt clutch. Later ones had a tension adjustment (you could externally adjust friction with allen key), but I think that came after 1980.

Thanks!

I removed the tilt clutch assembly last night, and the heavy snap ring on the concave spring washer side was not in the retaining slot (zero pressure on the clutches). I compressed and reseated the snap ring, then reinstalled. The lower unit now seems to be locking / staying in the down position when I try to pull it up manually. So in the next couple days I will be able to get back on the water for testing.



I agree that one would think that the forward thrust of the out drive would keep the drive in place... but that is not the case here. The lower unit also has a hydrofoil for faster planing installed on it.

 

[Rich B.]

Just wanted to give an update and put this thread to rest. I was able to get on the water and test the boat. Although, I was not able to pull a skier on the outing ( in-climate weather... again ) I did multiple full throttle pulls to max rpm; the out drive stayed in the full down position :thumb:. Thanks again,Howard Sterndrive.