Help needed with lower unit leak, and questions about mysterious "holes"?

[UglyBoost91]

Hey guys!

Full newbie here, so sorry for the silly questions. I have my first boat, and she has a 67' 45 horse Chrysler.

Anyhow, the first time out on the water, and a copious amount of water drained out of the lower unit. I had a problem with the lower unit output seal (the bearing retainer was cracked and crooked) so I think this is where the main issue is. I'm going to weld the broken ear/tab back on this weekend.

But, if this is not the issue, where else do these things leak? Does the upper section (on top of the horrible looking red RTV, connect with the bottom half? Where is the water collected for cooling on these things? Also, there are some mysterious holes that have been filled with RTV noted below by red aarows, and when I pushed on them, they fell into the housing and more water came out of these tiny holes!?!

I am lost! I really wanted to take her on the lake this sunday!
Thanks in advance from a full newbie!

Eric,

 

[Frank Acampora]

Re: Help needed with lower unit leak, and questions about mysterious "holes"?

Re: Help needed with lower unit leak, and questions about mysterious "holes"?



The four holes circled in red do not look stock. I would bet--especially if they are on both sides--that the previous owner drilled them to allow less exhaust backpressure, looking for more performance.

Any water that drains out of them doesn't matter. It is spent cooling water or water that collected inside while the engine was sitting low in the river.

The two small holes above the red RTV are drain holes and should be open.

The "stump-stabber" gearcase attaches to the upper half with a short stud inside behind the bearing carrier and a long stud at the front vee. The lower unit must be removed to separate the halves. There is a special gasket to replace the RTV and it should be used. This will be the same gasket used on early Force 50 engines so it is still available. I would look to this point as very suspect in leaking.

Other possible leaks can be at the fill and vent openings. They must be grunt tight with the plastic gaskets intact. the shift seasl and drive shaft seals can also be a source of leaks.

Cooling water enters through the screen on the rear of the exhaust snout. It is passed to the water pump then up to the block. After circulating through the block and head, some passes out with the exhaust and some passes out the circular idle relief vent in the center of the rear shroud. Look closely and you should be able to see it in these photos.

 

[UglyBoost91]

Re: Help needed with lower unit leak, and questions about mysterious "holes"?

Re: Help needed with lower unit leak, and questions about mysterious "holes"?

View attachment 164154View attachment 164155

The four holes circled in red do not look stock. I would bet--especially if they are on both sides--that the previous owner drilled them to allow less exhaust backpressure, looking for more performance.

Any water that drains out of them doesn't matter. It is spent cooling water or water that collected inside while the engine was sitting low in the river.

The two small holes above the red RTV are drain holes and should be open.

The "stump-stabber" gearcase attaches to the upper half with a short stud inside behind the bearing carrier and a long stud at the front vee. The lower unit must be removed to separate the halves. There is a special gasket to replace the RTV and it should be used. This will be the same gasket used on early Force 50 engines so it is still available. I would look to this point as very suspect in leaking.

Other possible leaks can be at the fill and vent openings. They must be grunt tight with the plastic gaskets intact. the shift seasl and drive shaft seals can also be a source of leaks.

Cooling water enters through the screen on the rear of the exhaust snout. It is passed to the water pump then up to the block. After circulating through the block and head, some passes out with the exhaust and some passes out the circular idle relief vent in the center of the rear shroud. Look closely and you should be able to see it in these photos.

Thank you very much! I have no idea why the lower two holes were pplugged then; but what are they vents for? They look like they go inside the housing?

The top 4 circled holes are not on the other side and look very professional, no way a hand drill was used if they were added later...

I will be doing the repairs tomorrow, so I will post back to let you know how it goes!
Eric,

 

[Frank Acampora]

Re: Help needed with lower unit leak, and questions about mysterious "holes"?

Re: Help needed with lower unit leak, and questions about mysterious "holes"?

Hmmm! Interesting. Perhaps the former owner had something bolted there. Are the 4 holes tapped?

The two lower holes are drains for blind cavities in the front and back of the unit. Without them, water that collects in these cavities will stand and eventually corrode the aluminum. Since your gearcase is attached with red RTV, I can only assume that the previous owner was trying to seal a leakfrom a broken gasket or such by filling them. I have a 67 Chrysler 55 and the front hole became clogged. The front cavity filled with silt over the course of several years. The silt turned to almost cement and stopped the shift rod from moving. I drilled a slightly higher hole at a angle to miss the front stud. At speed, this hole now blows water into the cavity and cleans it.

 

[Nordin]

Re: Help needed with lower unit leak, and questions about mysterious "holes"?

Re: Help needed with lower unit leak, and questions about mysterious "holes"?

UglyBoost91 and Frank The four holes beside the threaded holes for the waterimpeller housing is factory made. I have seen this on a housing from a Chrysler/West Bend 50Hp (think it was a 1965 or 66 year model. It had the none splinsed propshaft. In 1967 the propshaft had the splinsed on the 45, 50 and 55Hp). I think and is quite sure it is to drain the housing from water "faster". On later housing they were gone.

 

[Frank Acampora]

Re: Help needed with lower unit leak, and questions about mysterious "holes"?

Re: Help needed with lower unit leak, and questions about mysterious "holes"?

Thanks Nordin. I learn something new every day. My experience does not go back farther than 1967 splined shaft lower units.