1989 180/3.7LX 4 bbrl Mercruiser Alpha One drive Questions

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I tore up my seal when I last installed my lower to upper drives. I think I might have had the wrong oring (it was a little loose I had to force the drive up to fully seat)? What seals the drive shaft into the spline? There is a hole on the top of the spline the driveshaft goes into that would mean the cavity is full of oil that doesn't seem correct?

Also which way does the lower upper seal on upper housing on the driveshaft face, install seal spring side up or down??
 

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Also
I have an exhaust leak on the rear cylinder. I need to change of the gasket. Can I do this by just removing the bolts cleaning off manifold and head installing new gasket and torqueing?
It looks like I can slide it out enough to do it with out draining coolant I just changed it.
 

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nola mike

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There are two seals in that cavity. The upper seal is primarily responsible for keeping the oil in the housing. The lower seal is to keep water out of the normally dry cavity there. If that lower seal is shot, there's a good chance that your drive shaft is pitted and needs repair. The lower seal has the lip facing upward.

As for the manifold leak, you do need to remove the coolant, at least drain the heat exchanger. That looks like a pretty big gap, don't know if you'll be able to seal it by just cleaning it up, unless your gasket there is completely gone. Definitely check your head and manifold mating surfaces for straightness and pitting as well. Don't half ass it, it's easier to remove the riser and manifold completely.
 
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There are two seals in that cavity. The upper seal is primarily responsible for keeping the oil in the housing. The lower seal is to keep water out of the normally dry cavity there. If that lower seal is shot, there's a good chance that your drive shaft is pitted and needs repair. The lower seal has the lip facing upward.

As for the manifold leak, you do need to remove the coolant, at least drain the heat exchanger. That looks like a pretty big gap, don't know if you'll be able to seal it by just cleaning it up, unless your gasket there is completely gone. Definitely check your head and manifold mating surfaces for straightness and pitting as well. Don't half ass it, it's easier to remove the riser and manifold completely.
When you say "The lower seal has the lip facing upward." Does that meet the flat side up? So the spring open side would go down correct?

I tore up my seal when I last installed my lower to upper drives. I think I might have had the wrong oring(it was a little loose I had to force the drive up to fully seat)? What seals the drive shaft into the spline? There is a hole on the top of the spline the driveshaft goes into that would mean the cavity is full of oil that doesn't seem correct?
 
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I had water in my gear oil I drained it and pressure checked it It was bad. When I separated the drives and pressure checked the bottom was fine.
The upper when pressurizing air was coming thru splined (there is a hole on the top of spline where the drive shaft sits. (The drive shaft must be hollow). I plugged the spline and it held, the only seal that wasn't in play at that point was the seal i'm changing.
 

Scott06

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When you say "The lower seal has the lip facing upward." Does that meet the flat side up? So the spring open side would go down correct?

I tore up my seal when I last installed my lower to upper drives. I think I might have had the wrong oring(it was a little loose I had to force the drive up to fully seat)? What seals the drive shaft into the spline? There is a hole on the top of the spline the driveshaft goes into that would mean the cavity is full of oil that doesn't seem correct?
Spring side towards what you are trying to seal so upper seal keeps oil in - spring side up, Lower seal Keeps water out - spring side down.

dont need to seal drive shaft into the Spline whole assembly is bathed in lube
 

nola mike

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Spring side towards what you are trying to seal so upper seal keeps oil in - spring side up, Lower seal Keeps water out - spring side down.

dont need to seal drive shaft into the Spline whole assembly is bathed in lube
No, this actually isn't correct. Both seals have the spring side up. (Yes, I realize that that isn't how you'd think it should be)
Also, drive shaft definitely isn't hollow

Also also, a bad lower seal will still pressure test ok. You'll need to replace the upper as well.
 

Scott06

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No, this actually isn't correct. Both seals have the spring side up. (Yes, I realize that that isn't how you'd think it should be)
Also, drive shaft definitely isn't hollow

Also also, a bad lower seal will still pressure test ok. You'll need to replace the upper as well.
Mike is right both seals face up . Here is a link to download manual number six https://www.downloadboatmanuals.com/motors/mercury/mercury-mercruiser-service-manual/

page 3A-26 outlines assembly questions OP has
 
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No, this actually isn't correct. Both seals have the spring side up. (Yes, I realize that that isn't how you'd think it should be)
Also, drive shaft definitely isn't hollow

Also also, a bad lower seal will still pressure test ok. You'll need to replace the upper as well.
Thanks for the seal info. My drive is a 1989 Alpha one. It does have a oil pass thru (hollow shaft) on the that drive shaft(attached in a pic) that allows oil to flow from upper to lower. I had my drive upper gear set replaced about four years ago maybe they used a driveshaft from a alpha one gen 2. Or is was always assembled like that. I do see that there is a part number with oil hole. The drive was fine and held pressure and oil until the beginning of the this season when I messed up the lower seal installing the main drive shaft assembling the lower to upper. I know this is NOT the normal way. I believe in the GEN 2 the upper cavity is full of oil also.
 

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nola mike

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Guess I'm not clear what we're talking about. The driveshaft to the gear housing isn't hollow. The lubrication for the lower/gear housing is supplied by the passage between the 2 halves of the outdrive.
 
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Guess I'm not clear what we're talking about. The driveshaft to the gear housing isn't hollow. The lubrication for the lower/gear housing is supplied by the passage between the 2 halves of the outdrive.
I am NOT sure how to make it more clear. Upper shaft that the dower drive shaft in hollow. I personally have NOT saw this before but I have it apart right now and this is how mine is. I put a zip tie all the way thru.
 

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