69 Merc 1250 water pump and shift shaft seal question: UPDATE

[JasonJ]

When I was done for the season last year, I changed my lower unit oil, and it was a bit milky. I told myself I would change the seals the next spring. Well, it is now spring, and I have run it several times. I have a dirt driveway, so when it is sitting on the dirt, I never see any drippage. I now have it on the cement pad in front of my garage, and there is a small puddle of gear oil under the lower unit. The motor is tilted in the trailering position. When it was in my garage for the winter, it was down in the running position, and I did not have any leakage.<br /><br />I am suspecting maybe the shiftshaft seal and/or the water pump seals. I went to Napa the order both, figuring "why not". They not only had nothing in their books on the 68-69 Merc 1250, but they had practically nothing on inline 6s in general. What I need is another source, or equivelant part numbers, or whatever so I can fix this issue before I put it in the water for good. If I am wrong about what may be leaking, I'd like to know that too. From what I can tell, the gear oil is leaking from a hole on the starboard side, the hole looks similar to the water inlet holes, but more forward, near the leading edge of the lower unit. Clams probably know exactly what I am talking about. Any help is appreciated.

 

[Laddies]

Re: 69 Merc 1250 water pump and shift shaft seal question: UPDATE

sounds like shift saft seal but change them all while it's apart upper drive shaft# 18-2013 lower driveshaft#18-2007 shift shaft#18-2009

 

[emckelvy]

Re: 69 Merc 1250 water pump and shift shaft seal question: UPDATE

Sarge, any Merc dlr worth his salt should be able to look up those part numbers for you. Also try the www.dougrussell.com site, the "parts search" feature will lead you to a parts breakdown for your motor with illustrations and part numbers. Some of the prices may be a bit out of date so once you know the numbers, plug them into the www.mercurypartsexpress.com site for latest pricing and superceded parts info.<br /><br />Sure sounds like a shift shaft, the front cavity of the gearcase, with the little drain hole, is where you'd get oil leaking from the shift shaft/seal interface.<br /><br />You can buy the entire shift shaft bushing as one assy, with seal and O-ring included. If the shift shaft itself is badly rotted in the seal area, you'll want to replace that too. Later models use a stainless vice mild steel shaft, so you'll want that upgraded part. BTW don't just pull that shaft out indiscriminately, there's a trick to taking it out so you don't have to tear apart the lower unit to get it back in! If have to do that, let us know and we'll fill you in.<br /><br />Sierra Marine will also carry equivalent parts and a good online source is at www.boatfix.com <br /><br />Use their parts crossover feature to translate Merc part #s into Sierra:<br /><br /> http://www.boatfix.com/searchsierra.asp <br /><br />Typically, if only the shift shaft seal is leaking, you won't see a lot of water in the gear oil; the migration will be more gradual.<br /><br />Whereas, if the driveshaft seals under the water pump body are bad (or rusted driveshaft seal area), the oil will be quite milky and it'll happen very fast even after an oil changeout.<br /><br />HTH and Cheers to you on this Memorial Day Weekend........ed<br /><br />P.S. ain't them ol' Red Beasts sweet lookin'?? I still miss my Good Ole 1350!!!

 

[JasonJ]

Re: 69 Merc 1250 water pump and shift shaft seal question: UPDATE

So yesterday morning I went to my local Merc shop, and got the shift shaft bushing with seal, water pump impeller kit with all gaskets, and the two waterpump shaft seals. I tore into the 1250, and was rather horrified by what I saw. Bear in mind I have not had any cooling issues, and have always had a good pee stream, but I figured since I was replacing the seals, I may as well do the waterpump as well. <br /><br />The impeller was hard and had a permanet set to the blades, and cracks were developing. The steel cup that the impeller rides in had lost the retaining tab and had rotated in the housing, causing the driveshaft to be in constant contact with the cup. Both shaft seals were non-existant, and the shift shaft seal pretty much flowed lube freely. <br /><br />Needless to say, I spent the rest of the afternoon putting all the new parts in. I launched this morning, the pump is pumping very strong, the pee stream is damn near a pressure washer when I am up on plane cruising. No lube had leaked overnight. Now my boat is in the water for the season, and I don't have to worry about the lower unit....

 

[tengals123]

Re: 69 Merc 1250 water pump and shift shaft seal question: UPDATE

wow, that must be a good feeling. I believe I have a similar problem.<br /><br />cheers