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Lower Unit seals- which ones fail more often?

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soonrfish

New member
waiting on some parts to complete my lower unit seal kit. while tearing it down, I decided to replace all seals and gaskets. nothing looked like an obvious failure and cause for water leakage, but water is getting in the unit somehow. the only thing i noticed is that the shaft seals under the water pump MAY be the cause as they didnt seem as tight as the seals around the prop shaft are. also going to replace the drain plug o rings. could not pressure test it (i made a previous post when i had a piece break off) this is my first boat motor to work on after years of atv engines.

my question is, does water tend to get in the lower unit from the shift lever or the drive shaft seals more often when there is a failure?
 
I'd say drive shaft because of it constantly turning, but do like you said and replace all of them while you have it apart. You basically mentioned all the places water gets in other than possibly a crack somewhere which is where a pressure test would be helpful. Just be careful removing old seals. Yesterday i "tried" to remove my prop shaft seal on my 1963 5.5 hp Johnson and broke the bearing housing. It was pretty bad looking and the outer housing of the seal was just bending over.

Just curious, what type of sealant are you planning to use for the spaghetti seal?
 
The best way to do a re-seal job on a lower unit is to pressure and vacuum check it before taking it apart. No guess work as to where it's leaking.
 
Thanks Flathead, i am using the Permatex avaition gasket sealer #80019 after looking at many threads. it is a 93 Johnson fast strike 150

Boobie, I made a thread earlier about a piece that chipped off my lower unit and there was no way to pressure test because of it. the seal around the prop was already ruined so it needed replaced. after running it after that repair, i was still getting water in my lower unit and thats why i have dropped it and decided to replaced both of the others since its open. i will pressure test it after the repair. thanks
 
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