Water in lower unit...

[JSGAuto]

Hi,<br />This fall while I was winterizing my engine I found water in the lower unit. What has to be replaced to fix this? I am mechanicly inclined and will be doing the work myself. <br /><br />1977<br />70hp Mercury<br /><br />Thanks,<br />Jim

 

[mellowyellow]

Re: Water in lower unit...

as easy as a bad fill/drain screw gasket or could<br />need a complete L/U seal kit. was there any metal <br />shavings on the drain screw?<br />real easy to tear apart if u got the right tools.<br />good luck,<br />M.Y.

 

[JSGAuto]

Re: Water in lower unit...

I doubt that it is the drain plug. It looks good and seems to seal the oil inside when it is sitting. So I think it would be best to replace the seals then. I am also planing on replacing the waterpump at the same time. <br />Where can I purchase theses parts for a decent price? I looked at Mecury's website. But my engine is to old for the serial number search. <br /><br />Thanks for the quick reply!!<br />Jim

 

[mellowyellow]

Re: Water in lower unit...

hundreds on the web, here's a start:<br /> http://www.oldmercs.com/index.htm <br />good luck,<br />M.Y.

 

[BF]

Re: Water in lower unit...

My advise is to pressure test the lower unit before you decide to do the whole seal thing. Take the lower unit (LU) off. While it's drained (no oil), figure out a way to pressurize it. I've done it with a rubber stopper that I drilled a small hole through, slipped a piece of tubing through the hole and siliconed in place. Then used a syringe to pump air into the LU. I had T'd a pressure gauge on the line with the syringe (and a valve, so I could close off the LU, refill the syringe and give it another push of air). 10 psi is what shops will test with. Lay the LU in a kiddie pool (or something), and see where the bubbles come from. Mine wouldn't hold any pressure at all, and when I gave it a syringe of air, I got a nice push of bubbles from under the water pump. I replaced the pump base (new seals around driveshaft), and voila. I didn't need to mess with the other seals at all. I pressure tested it again after doing the water pump, and it held 10 PSI for hours, no problem. I used it the rest of last season, and the oil was perfect when I changed it in the fall.<br /><br />So the moral is, I'm really glad I didn't take all the LU apart because of a bad water pump seal! BTW, mine is a 150 HP V6, but that doesn't matter.<br /><br />good luck.<br /><br />Brent

 

[JSGAuto]

Re: Water in lower unit...

That is a great idea!<br />I am going to give that a try!<br /><br />Thanks,<br />Jim

 

[fcharb]

Re: Water in lower unit...

You can pressurize it with the same adapter that comes with pump to fill the lower unit with oil (Wal-Mart). You probably have this already. Hope this helps.

 

[tmac58star]

Re: Water in lower unit...

Yup, good advice on all counts so far. I have a similar vintage Merc...its a 73 500 50 hp. I had my local shop reseal my lower last summer. Cost about $200 including labor, seals and pressure testing...plus they had to send the driveshaft out for resurfacing. It had become pitted through the years and wasn't sealing in/around the water pump. So that's a ballpark cost if you have it done...should be pretty similar I would think. Look at the surface of you drive shaft down by the water pump. If its nice and smooth, then you probably just need new shift shaft, pump and/or prop shaft seal(s).