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water in lower unit oil

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seasprite86

New member
Hello everyone!! I have a 86 mercruiser alpha 1 and last summer I found water in the lower unit oil. I changed the oil, installed new gaskets on the drain and vent screws. This fall I was winterizing and found the oil milky again. Now my question is how else is water able to get in. I have never had the lower unit apart. So i am not sure what else to do. I could use some advice.
 
Needs a full seal kit.also,since it shares its oil with the upper section as well,would suggest doing a seal kit in that.Im in the middle of the same thing,and you need a few special tools .some Im making,but some I may have to go to marine shop to get them to undo things.You may need a set of bearings too.I would suggest taking it to a marine shop,unless yr comfortable with engineering,and have the w/shop manuals
 
OK. Welcome aboard.

First you will need to drain and remove the drive. Next you will need a cooling system pressure tester and a gear oil fill pump from your local Marine store. Remove the radiator adapter from the pressure tester and the fitting on the hose of the gear oil pump and attach the gear oil pump fitting to the pressure tester.

Attach the pressure tester to the drive drain plug and pump it up to 13-14 lbs. Take a look at the prop shaft, the input shaft on the upper and the input shaft of the lower. Listen for the air leak. If these areas are not leaking you need to separate the upper and the lower units and remove the water pump upper housing. Hook your pressure tester to the lower and pump it while holding your finger over the oil pass through hole. Check the input shaft seat and the shifter seal.
 
Like budgie said, consider a seal kit. There are several places water can get in, some more susceptiable than others. Unless this has been done before, the seals could be 25 years old! Some aren't too bad to replace, others, well, if you're not familiar with the process and don't have the tools to do it right, send it in to a certified shop. You have to weigh what you may save by doing it yourself against what it will cost if you make a mistake. Drives can go very wrong very quickly if not done right, and they are not cheap to replace. That's why regular maintenance is critical.
 
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