Hints when replacing lower unit oil seals on MK 1000?

[Caddy_Kid]

I have a '65 Mark 1000 that I'm working over. Currently about to finish rebuilding the carbs and fuel pumps. The lower unit oil is milky yellow and leaks out when the motor is on high tilt only.<br /><br />Purchased two oil seals for the upper and lower part of the impeller housing from Grubbs when I bought the rebuild kits. Any hints for when I'm changing these? Now that I look at it, it sounds like I also need a shift shaft bushing? The 1965 and prior Mercury service manual that I have makes it look rather simple, just like changing the impeller. But they also go into shimming, gear lash, engagement, etc. Thought I would see if I was on the right track.<br /><br />Currently it dosent engage in reverse worth a darn and dosent lock in reverse at all. I dont really use reverse as I'm used to a direct drive Merc, but thought I would at least take a look at it when I have the lower unit off. Am I on the right track? Thanks.

 

[Laddies]

Re: Hints when replacing lower unit oil seals on MK 1000?

When removing the shift shaft bushing use care not to let the shaft raise up or you will have to tear the unit down to get it back in the shift cam

 

[Caddy_Kid]

Re: Hints when replacing lower unit oil seals on MK 1000?

I thought I had read something like that somewhere. So far I cant find a seperate shift shaft bushing offered by Grubbs. I will call them tomorrow and ask. They do have a whole lower unit seal kit for $73 and some change, but that is a bit more than I think I want to spend, since I dont really need it all, but I beleive that it does include a shift shaft bushing. I figure I'll start with this and go from there if it still leaks water. Thanks.

 

[Laddies]

Re: Hints when replacing lower unit oil seals on MK 1000?

Go to your NAPA store and have them look in thier marine catalog

 

[Caddy_Kid]

Re: Hints when replacing lower unit oil seals on MK 1000?

Was able to locate a Shift Shaft Bushing from Grubbs, but the darn thing is nearly $20. Oh well, do it all at once, right? Also ordered new oil fill and vent gasket washers, just in case. Figure if this doesnt cure it then it must be the prop shaft seals, but since they require a special tool (and can be done with the lower unit still on) I figure I will tackle the harder ones first.

 

[Laddies]

Re: Hints when replacing lower unit oil seals on MK 1000?

Good luck take your time and it will go good--Bob

 

[Caddy_Kid]

Re: Hints when replacing lower unit oil seals on MK 1000?

So I'm stuck at step one. I have removed the three nuts on the leading edge of the lower unit, and removed the two nuts under the anti-cavitation plate (actually the studs were what unthreaded with the nuts still on it, but they are free at the moment). Its a long shaft so there is a large spacer between the engine and the lower unit. So far nothing will budge. I imagine it is on there pretty good, so I have it soaking in WD-40. Tried my 6lb dead blow hammer on it, but nothing. According to the manual I have done everything I need to. Should I just let it sit overnight and go from there? Thanks.

 

[Laddies]

Re: Hints when replacing lower unit oil seals on MK 1000?

Remove the trim tab there is another bolt underneith the tab

 

[Caddy_Kid]

Re: Hints when replacing lower unit oil seals on MK 1000?

Nuts. Thats got to be the toughest one to get to. Will head to Harbor Freight this afternoon to see if I can get a long handled allen wrench. Thanks.

 

[Caddy_Kid]

Re: Hints when replacing lower unit oil seals on MK 1000?

Got it! On mine it is a 3/8" allen head bolt. Couldnt find an allen with a long enough handle, but was able to borrow one from the owner of a marina here. He welded on a piece of 3/8" allen wrench to a long bolt and used a wrench to turn the bolt head. Worked great. Have the water pump seals out and replaced, and will replace the water pump impeller, gaskets, wearplate, etc. Didnt realize that the flush plug on the side of the lower unit was threaded into the water pump base, so it was hard to remove until I discovered that.<br /><br />Looks like the shift shaft seal is probably what was leaking the most. Thats the only place that the oil could leak out of to come out the drain hole on the leading edge of the lower unit, which is what I was seeing. Also didnt realize that that seal is so large. So the $20 seems like a pretty good deal now! So far going really well. Glad I didnt take it to a shop or it would cost as much as the motor though!

 

[Caddy_Kid]

Re: Hints when replacing lower unit oil seals on MK 1000?

Its put back together now. Replaced the shift shaft bushing, two oil seals in the bottom of the water pump housing, the one seal in the top, installed a new impeller and water pump rebuild kit (gaskets, O ring, wear plate, water tube guide). The drive shaft had some rust on it where the lower water pump housing oil seals are, so I cleaned it off with a dremel and packed the space between the seals with grease. I hope it can seal with the pitting that occurred.

Had to make a spanner socket that was deep and big enough to take the shift shaft bushing out. I used a piece of steel pipe and a steel pipe connector. Cut and ground the connector so that it had two "ears" (using the seam on the connector for strength as well as an easy way to find center) that fit in the shift shaft bushing, attached it to the pipe, and had to use a big pipe wrench on the pipe to get it to come out. It was really galled in there. Re-installed with some grease on the threads. I included a picture.

Made sure to loosen the shift shaft one turn at a time, then tap the shaft back down, just in case removing it walked it up. Had no problems! Got it all put back togeather and it still shifts like it should.

Also fixed the lack of a reverse lock out. Some previous owner had installed the lock out actuator arm into the lower unit incorrectly. It wasnt in the hole in a nylon bushing that keep the shift shaft and arm in the propper alignment. Easy enough to get wrong, as I did it once, which is how I learned where it should go! Got it in the right hole and adjusted, and it works great now.

So all in all it was very successful. I wouldnt have a problem doing it in the future on another motor. Also purchased a lower unit oil pump. It threads into the lower unit drain hole and pumps from an oil bottle. Real time saver, and only $10.

UPDATE: Took the boat to the lake this weekend and after a good day at the lake, the lower unit oil is nice and amber, just like when I put it in! Before the repair, it would be mustard yellow after just a couple hours. So it worked!