War with lower unit

[Yesterday]

Re: War with lower unit



As for the water pump, something didn't sit right with me about this so I started looking for OEM pictures of the original. It looks to me like a chunk of plastic from the pump housing has melted down into the pump around the drive shaft, though if so it left a remarkably clean hole. My present theory is that this may have been the original cause of the water getting into my shaft housing and why there's so much corrosion? The thing is, the drive shaft starts to swell right around that area and the lower the seal surface is to the LU the better chance I have of getting a good seal. Both sierra and Mallory's after market pump housings seem higher up if anything, so I don't know what to do with this situation. Any advise would be appreciated. Also: Should this be a new topic? I'm not sure of the forum's protocol in this sense.

 

[Yesterday]

Re: War with lower unit

And for those following this thread or anyone encountering similar down the road: The drive shaft was swollen just below the crank splines so badly that I had to do a significant amount of sanding with a dremel, just to get the water pump housing and impeller off. Said swelling would have been right at the point where the crank seal carrier was lodged, and I would guess it was a strong 1/16" full circumference, beyond it's original size!!

 

[Yesterday]

Re: War with lower unit



This is the biggest concern. The drive-shaft is in bad bad shape!

 

[mercurymang]

Re: War with lower unit

Here's my opinion. Take if for what it's worth. The first picture with scoring. Is there a seal there. If not, I don't think it's a big deal. I don't think there much to worry about regarding the pitting on the general shaft unless it has been weakened to the point where it would break. Lastly, the one thing I might be concerned about is what those damaged splines may do to your crankshaft.

 

[Yesterday]

Re: War with lower unit

Here's my opinion. Take if for what it's worth. The first picture with scoring. Is there a seal there. If not, I don't think it's a big deal.

It seems to indeed be a seat for a seal. Until I wrap my head around what's out of place with the original water pump though, I'm not sure what impact it will have with a replacement.

I don't think there much to worry about regarding the pitting on the general shaft unless it has been weakened to the point where it would break.

Agreed. I will take steps to prevent further rusting, but otherwise it just looks ugly. LOL

Lastly, the one thing I might be concerned about is what those damaged splines may do to your crankshaft.

Since they came out, they'll go back in. The splines below the crank look worse because I didn't put a lot of effort into cleaning that area up yet. They will be in far better shape going back in. At least the swollen area is now of a normal size.

 

[Moody Blue]

Re: War with lower unit

The seal grooves you pointed out in your last photos are a non-issue. The new pump housings don't even have seals there anymore. They were done away with many years ago. You should have seen the driveshaft I replaced on my motor a couple years ago. The older shafts were all carbon steel without the stainless steel pump section. The seal areas on that shaft were badly pitted, not just grooved.

Be sure to pull the waterpump base as well, because there are two driveshaft seals at the bottom of the base. Those two seals ARE important because they keep water out of the LU. When you replace the seals, be sure to replace the o-ring seal on the waterpump base as well.

Your making great progress.

 

[Bosunsmate]

Re: War with lower unit

Wow those driveshafts are expensive to replace new.
I use permatex aviation form a gasket on the splines ($8) and i drop the leg every few months and redo it (its only a 20minute job when its done regularly)
Yeah i agree with mercury mang about that seal and Moody Blue about the bottom ones, the driveshaft will probably be pitted there too.

Make sure when you reinstall you put on the slinger too as that helps stop water shooting up into the crankshaft end as well as vice versa

 

[Yesterday]

Re: War with lower unit

@MB: I think I may have caught a post you'd made about that looking for a replacement, If I'm right some sort of sleeves were discussed?
Great reminder on the lower part of the pump, in fact I think I'll tear that out now before I forget!!

@Bosunsmate :
What is a "slinger"? I shall seek out some permatex!! I think I may also spray the shaft with some linoleum based spray.
<edit> Slinger seal: Yeah that one's been bugging me. It seems sort of silly.since it spins on the shaft and chaffs on the top of the pump. Strikes me as a poor design but anyway, I'll not forget it.!

 

[Bosunsmate]

Re: War with lower unit

Yep that permatex stuff is good, its all over most of my equipment now. It takes a while to set so you dont need to rush on reassemble, id say it would take even longer in your current winter so you'd probably best leave it inside while it sets.
Yeah the slinger does seem a bit superfluous but it is meant to stop any water bursting up from a broken seal from the water pump and hitting the crankshaft seal and causing your problem again there and also protects the top seal of the waterpump housing from debris thrown down from the exhaust.
I put one on just in case it was important, im guessing it wasnt some guy at mercs april fools prank but i havent seen it on many other motors.

 

[Yesterday]

Re: War with lower unit

I guess there's sense in that!! I redid the seals in the lower half of the water pump and the originals were shot. Thankfully the drive shaft was in good shape down there so it wasn't a problem. Thus far it seems this LU was leaking around the prop shaft and under that water pump. Surprising there wasn't any damage to the bearing etc. but I don't think this motor has seen any real use in years. Did I read the Seloc manual right in that the spanner nut needs 210 ft/lbs of torque, and did I read elsewhere that it was a critical requirement? That's a remarkably high degree of tightening!! I guess I will have to buy the proper tool!

 

[Moody Blue]

Re: War with lower unit

Yep, it needs to be on TIGHT. If undertorqued, the reverse gear will not engage properly wearing out the clutchdog.

I made a crude tool for removing and installing the nut, so when it came time to install, I layed the LU on the ground and stood on the handle of the tool to "torque" the nut. Handle was 18" long and I weigh 190Ib, so I figured I was standing on the last 6" or so of the handle which ROUGHLY works out to 190Ib x 14" = 221ft/Ib. Seemed to work for me.

 

[mercurymang]

Re: War with lower unit

Yep, it needs to be on TIGHT. If undertorqued, the reverse gear will not engage properly wearing out the clutchdog.

I made a crude tool for removing and installing the nut, so when it came time to install, I layed the LU on the ground and stood on the handle of the tool to "torque" the nut. Handle was 18" long and I weigh 190Ib, so I figured I was standing on the last 6" or so of the handle which ROUGHLY works out to 190Ib x 14" = 221ft/Ib. Seemed to work for me.

Thats cool. I like you use of Math there.

 

[Yesterday]

Re: War with lower unit

MB that's a slick method! I actually have a fairly large torque wrench though so fortunately I won't have to rely on my 160lbs of weight. Think I'd need a little more distance there, than you did!

Whoa am I seeing right? are the splines in the crank of these engines particularly shallow? I was shocked to see mine!

 

[Yesterday]

Re: War with lower unit

 

[Moody Blue]

Re: War with lower unit

The splines are not a real tight fit to the driveshaft. I'm not certain, but I think the crank splines would be harder than the driveshaft splines. That's the way I would have designed it anyways . Inspect the driveshaft splines for worn edges. If they look reasonable, then you're probably good to go.

While you're this far along, you should replace the two lower crankshaft seals. From the photo it looks like one of them is damaged. This is a common failure in the old Mercs resulting in water being sucked into the crankcase - a bad day. This was the initial reason for tearing my Merc apart. Things have progressed from there.

 

[Yesterday]

Re: War with lower unit

I'm taking that carrier out so I can see what's going on inside for sure. I figure I might as well do it right!!

 

[Yesterday]

Re: War with lower unit





@MoodyBlue:
Keen eye on that seal. Though the inner one was still intact, the outer most seal was not! The spring and rubber lip of the seal literally fell out! I'm concerned about the crank where the outer seal would ride.

 

[Bosunsmate]

Re: War with lower unit

Did you change the seal on the shiftshaft? Replacing the one on the top of the bushing and then putting permatex aviation form a gasket on the busings threads and housing is the way i do it. Lips facing up on the seal.
Also there is a little spacer that goes just under the reverse locking cam, its meant to have grease in it too, seems, possibly, like the same type of accessory designed by the slinger engineer but i always fill the void with marine grease (maybe there is meant to be a rubber washer in there, il see if my manual says so)

 

[Yesterday]

Re: War with lower unit

both seals in the shift shaft bushing are done as well as the O ring. I had bought a full seal kit so if it was replaceable, I replaced it. Spacer under the cam? Hmmm nope I didn't see anything there originally nor in the diagrams! Don't make me pull that LU apart again! LOL
(It's not torqued yet)

 

[Bosunsmate]

Re: War with lower unit

Sorry but my Mercury Master Manual doesnt give an answer to this, it just says add...Nylon spacer.. and lubricate heavily. Im unsure if the washer i had with mine did actually fit in the spacer groove, i was under the impression it needed grease and the grease has stayed in their between servicings