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OMC gasket between upper and lower unit

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decker5484

New member
Hello all,

I am in the process of putting a new upper unit on the lower and don't see where there was a gasket between the two. Is there supposed to be a gasket here or do they just bolt together? Also, should I replace all the internal gaskets and O-rings since I have it apart or leave them alone? I never had any problems with water getting into the oil. Thanks much!
 
That would probably help, eh? I have a 1991 OMC Cobra 4.3 V6. My Seloc manual doesn't say anything about putting a gasket on when I bolt the upper and lower together. I just assumed there would be one there I guess. In the lower unit, there is a housing (maybe water passage) that the intermediate shaft goes through. On that housing, there are two O-rings. Is that all that keeps the lower unit oil out of the lower unit housing. My guess is the lower unit is full of water once the boat is launched??? Thanks much!
 
Everything you typed is true. No gasket, two O-rings, actually 3, you cant see one. Make sure the water tube is in the upper and it hits in the guide in the lower as you set it down. Also measure the shift rod height before you put the two together.
 
Awesome! Thanks for your reply! A couple other questions. I measured the shift rod in the full down position. This is just to make sure it doesn't get turned (raised or lowered) correct? While I have the upper off, should I pull the water passage housing and the shift rod cover and re-seal them? I bought the gasket kit and wondered if I should reseal them while its apart. Thanks
 
The shift rod height is measured in neutral from the lower unit housing not the shift shaft cover plate. I wouldn't do any of the other things. The shift shaft should move up and down with EASE. If it's too tight the o-ring seal has swelled and grabbing the shaft. If this has happened it's much easier to replace the shift rod cover plate complete than try and screw with that o-ring. The whole shift shaft cover plates are not that spendy.
 
You've been very helpful. Thanks much! The shift rod moves easily but I guess I measured it wrong. I measured it in the full down position from the cover plate. I'll remeasure it again in neutral from the housing. What's the purpose in measuring it anyway? Is it threaded at the base? I see it turns (I actually taped it in place because I have a little guy that would love to spin the hell out of it) and just assumed it's probably threaded at the base. This is my first time doing any of this, so again, thanks a lot!
 
If not adjusted right it won't go into one or the other gear. Yes it has a lot of threads on the other end and it pulls or pushes on the shifter in the lower gear set.
 
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