1972 merc 9.8-several questions

[jbjennings]

I've finally made some progress on my merd 9.8. It had a couple of pieces of hardened rubber gasket or fuel line in the fuel pump check valves which was possibly causing a slight miss as wide open every once in a while. I don't know if that was the cause but it's not doing it now. I also have got the water pump working well. I resealed the lower unit and am still getting a slight leak (milky but not bad milky lower unit oil after burning about 1 gallon of gas). The only seal that is not new is the prop shaft seal. Long story why it's not new. The prop shaft did have some miniscule pitting at the seal like most do. Here's my questions: Has anyone had any experience having the drive and prop shaft welded back up and having it taken back down on a lathe? How did it turn out and how long did it last as far as holding a good seal? How did you polish it? Also, Is the reverse gear supposed to slip on hard throttle ( I noticed the clutch was different on the reverse gear compared to the forward side of the clutch)?. I'd like to get this old motor in good shape because the power head has very, very low hours and it cranks like a dream and idles and runs wide open that way, too. I also really like 70's 9.8 and 20 horse mercurys although in my opinion they have some really annoying ignition parts and the drive shaft/prop shaft problems (cast iron). Mine has the newer late 70's drive shaft I believe, but oddly enough the part that counts where it seals is stainless whereas the top part about 2 inches out of the water pump up is really corroded and appears to be cast iron. Any other ideas on how to get this lower unit in tip-top shape? Is there a source for reasonably priced new drive/prop shafts? Any ideas would be helpful.
THanks,
JBJennings

 

[Laddies]

Re: 1972 merc 9.8-several questions

We take shafts to our local hydralic repair shop all the time they use spary welding and grind back to original size and the reverse gear don't rachet on that engine

 

[jbjennings]

Re: 1972 merc 9.8-several questions

Thanks,
I think I'll try that. I was wondering, though, what is spary welding? Is it particularly hard so the seal won't wear it down? How much do they usually charge where you are?
JBJ

 

[Laddies]

Re: 1972 merc 9.8-several questions

Sorry about my crappy spelling, the word was suppose to be spray--Bob

 

[dajohnson53]

Re: 1972 merc 9.8-several questions

Hey Bob - as usual I appreciate your information and comments.

This idea intrigues me. My '74 9.8, after some messing, seems to be running very well. The only remaining issue is one I thought I'd just have to live with.

I can't get the lower unit completely sealed. I've had it into two different shops, the last of which is really trustworthy and I think they did their best to seal it up. All seals have been replaced. The leaking seems to be around the drive shaft seal because it is corroded and won't make a good seal. They cleaned it up as best they could and it made a noticable improvement. I've been living with it by simply changing the l/u oil every 30 or so hours, maybe a couple times a season, no big deal. It really just shows a little milkyness at that point.

How much does this procedure cost? Do you think it's worth it?

 

[Laddies]

Re: 1972 merc 9.8-several questions

The cost of the repair is based on a hourly figure and has ran as low as $35 on smaller shafts like we are talking about on these engine to as high as $150 on larger shafts in bad shape the shops can very the hardness of the weld by using different spray materials

 

[jbjennings]

Re: 1972 merc 9.8-several questions

Laddies seems to know very little about Mercury motors and probably just lucked out with this answer!


Very interesting, I have never heard of spray welding but am going to call around and find out who can do it.....Thanks again!
JBJ