Mid 70's Merc 115 (tower o' power ) 6cyl

[joemamma_222]

Hey All ! Back to the forums for some answers ! I noticed there was water in my lowerunit on my outboard last year. I've been putting it off but nows the time to investigate. I've got a manual on the way but wondered if you all might be able to give me some insight as to why/Probable cause for the water in there. Setting aside the Fill/vent screw Washers what else am I looking at here ? Someone said it could be a prop seal and other than that the lowerunit would have to be cracked to let water in there right ? I wanted to take a look tonight could someone walk me thru taking the prop off and inspecting the seal ? I know I need a manual but I've got time to inspect tonight. Is it hard or do I need any special tools to get at the prop seal ? Is it jsut an oversized rubber washer ? thanks for any help !!!<br />should the motor be in gear to take the prop Nut off ? <br />Joe in ohio

 

[joemamma_222]

Re: Mid 70's Merc 115 (tower o' power ) 6cyl

Here's a pic of the motor Anyone got an Idea ?<br /><br /> http://putfile.com/pic.php?pic=3/6506211110.jpg&s=x10

 

[roger3645]

Re: Mid 70's Merc 115 (tower o' power ) 6cyl

Joe the seal kit for that motor will go for about $60-$70 bucks, which includes water pump gaskets and seals. I'd start off with a pressure test of the lower unit. Remove the prop, you may be able to bust that prop nut by just holding the prop with your hand or knee. With luck the prop is not stuck and will slide off. If not search the forum for stuck prop. Drain the oil from lower unit.Place the motor in nuetral, (some like fwd). Remove the trim tab, there's a lower unit bolt under there, remove that bolt, and then you have 5 nuts to remove. Should be able to remove lower unit. To conduct the pressure test, you will need: tire pump with guage (bicycle pump will work), inner tube or a tire air valve. The idea here is you want to fill the lower unit with about 10 psi to see if it holds the air. You can also place the LU in a test tank of water to look for air bubbles to point to the location of the leak. You'll need to cut the air valve off of the inner tube and trim it to fit and seal in LU oil fill/drain screw hole. Also you can rig up something using the tube you use to fill the LU with oil. Search the forum for pressure testing the lower unit. Maybe some one can explain it better than I can. Unless the seal is in really bad shape you can't really tell if it leaks by just looking at it. You have LU seals in the shift shaft, prop shaft, and water pump assembly.

 

[joemamma_222]

Re: Mid 70's Merc 115 (tower o' power ) 6cyl

Thanks roger... appreciate the info.. Still waiting on the book. I didn;t know there were 3 seals total that could be leaking...I'll have to check it out in a few more weeks and see what I see. back to my original question though. Do you need a special tool and how hard is it to put in a prop seal ?<br />thanks !<br />Joe.

 

[Chris1956]

Re: Mid 70's Merc 115 (tower o' power ) 6cyl

Joe, The lower unit has an o-ring and gaskets on the pump base, as well as a drive shaft seal in the pump base. This is where most of the leaks (IMHO) occur. All the seals but the prop seal are easy to replace. It is easier and almost as cheap to buy the lower part of the waterpump in order to get a new drive shaft seal. I recommend this course of action. You will need to match the old O-ring to the new one to make sure you have the right fit.