'73 Mercury 110 9.8 Corroded driveshaft = poor water pump performance?

[F4UCorsair]

Hi Everyone, This is my first post. Did some quick searching and didnt find what I was looking for. I just bought a very nice little 9.8 110 from a co worker for $100. Got it home and it ran like a champ after sitting for years. As expected the water pump was toast. Rebuilt the pump with the kit from oldmerc.com and got just a trickle from the pisser. After watching videos of other peoples 9.8's I realized mine isnt preforming at all.

So, I started thinking maybe the corroded driveshaft isnt sealing to the pump housing properly and causing poor water pump performance? Thats my question to you guys, Does the interface between the driveshaft and waterpump housing need to be sealed? And do I need to new driveshaft?

 

[jbjennings]

Re: '73 Mercury 110 9.8 Corroded driveshaft = poor water pump performance?

Well, yes, you do need a new driveshaft. I shudder to think of how that shaft looks underneath the water pump, and what your gears look like inside the lower unit. I would say that is a saltwater motor, if I had to guess.
If you can find one that will fit from a '76 or later 9.8hp merc, it will be stainless steel.
As to your pumping question---- make sure the pickup tube is sealed really well where it enters the pump, make sure your pump insert is not grooved too badly, and yes, it needs a decent seal at the top of the housing. You should really think about tearing down your whole lower unit. Also, you have impeller blades going the wrong direction. I think you may have some exhaust leaks into your pump and water line sections, exhaust cover leaks, drive shaft leaks, or trash in the indicator hole.
JMO,
JBJ

 

[F4UCorsair]

Re: '73 Mercury 110 9.8 Corroded driveshaft = poor water pump performance?

Thanks jb! Yeah I figured a new driveshaft was in order. Just wanted to hear someone else say it. I like the idea of the stainless shaft, ill have to see if they are interchangeable.

Unbelievably, below the water pump, the driveshaft is near spotless and the bearing that is visible is flawless. The motor goes in and out of reverese, neutral, forward very well, so im hoping when I tear into the bottom end I dont find too many suprises.

 

[jbjennings]

Re: '73 Mercury 110 9.8 Corroded driveshaft = poor water pump performance?

I'd get a second opinion if that shift looks good at the seal surface......... They're hard to find that will hold a good seal. Even if it's pitted like that, it still may be workable. Those 70's mercs have to be just right in the water pumping department or they'll have trouble like you describe. I don't think that shaft is workable, but there's lots of real mechanics here that may know otherwise.
Good luck,
JBJ

 

[Mi duckdown]

Re: '73 Mercury 110 9.8 Corroded driveshaft = poor water pump performance?

Pull the upper pump housing off and send pics. Also pics of the shift shaft.
What does the lower end fluid look like, water/ milky?
Sorry. the lower pump housing/base

 

[F4UCorsair]

Re: '73 Mercury 110 9.8 Corroded driveshaft = poor water pump performance?

Hey duckdown, Ill try to get some pictures tonight. The upper pump housing, after further inspection needs a new driveshaft gasket for sure. The bearing below the water pump is near perfect, no corrosion or damage at all. When I got the motor the lower unit oil was drained. When I refilled it for the first time and ran it with the new impeller installed, water leaked past the lower pump housing seal and turned my fresh oil into milk. So i know there is a definate sealing issue. As far as the shift shaft, its damn near perfect, no corrosion at all. the shift shaft seal also appears to be in good shape.

So driveshafts for these old mercs are hard to find?

I was thinking about taking the driveshaft out and taking it to a machinist buddy of mine to build up the sealing surfaces with a MIG welder and bringing it back to tolerance on a lathe. Anyone ever done this?

 

[chum1]

Re: '73 Mercury 110 9.8 Corroded driveshaft = poor water pump performance?

Hello F, just went through this on a customers motor, "rusty shaft around water pump area" after much research and a trip to the machine shop for correct non existent very small speedy sleeve/bushing/custom made anything i came to the conclusion it was more economical to find a newer/running,partial running motor to fix w stainless shaft then to machine or buy a new rare shaft for big bucks. There may be a donor lower end somewhere that may work but doubtful. Thought about jb weld but would'nt last very long and it would chew up the new water pump, maybe someone else has an easy fix.

 

[Mi duckdown]

Re: '73 Mercury 110 9.8 Corroded driveshaft = poor water pump performance?

Not mig. but I turned them down and silver solderd/braised them then turned back to specs. there are both running to date.
But if you can find a speedy sleeve and have the shaft turned to the right specs than your gold.
my Brother had one done. last year. Cost him 100 bucks.

 

[F4UCorsair]

Re: '73 Mercury 110 9.8 Corroded driveshaft = poor water pump performance?

Thanks everyone! Very helpful! I Think im going to give the MIG weld and lathe idea a try. Ill update when its done.

 

[Auminer]

Re: '73 Mercury 110 9.8 Corroded driveshaft = poor water pump performance?

Also, you have impeller blades going the wrong direction.

Heh, which ones?