Merc Problems, should i fix and how much?

[merc_500]

I have a '74 Mercury 500 4cylinder twin carb. The motor runs great but the problem is in the lower unit. <br /><br />The gearcase needs to be re-sealed, and it needs another prop (rebuilt of course) <br /><br />How much does it cost to be re-sealed? What all is involved and could i do it myself? What other things should be checked out? <br /><br />Thanks alot guys!

 

[WillyBWright]

Re: Merc Problems, should i fix and how much?

You can do the driveshaft seals with common tools. The shift shaft and propshaft seals require special tools to remove the housings. It could cost considerably if the shafts have grooves where the seals would seat. Otherwise I'd think in the $250 ballpark. With the special tools it can be done in about 2 hours. Maybe a bit more, maybe a bit less. Then again, if you trailer it or it doesn't sit in the water all the time, you can buy a whole lotta gearlube for $250. Just make dang sure you change it before freezing weather sets in. That's the demise of many a 500 Merc.

 

[merc_500]

Re: Merc Problems, should i fix and how much?

Hmmm, maybe i'll take it to a dealer and get him to give me an estimate as well. How much do you think it would be for him to get the motor running A-1? That includes changing those seals as well as possibly having to set the distributor?

 

[bh357]

Re: Merc Problems, should i fix and how much?

You should be able to do most of the work yourself, or all of the work if you have the special tools that WillyBWright mentioned. Make sure you have a service manual.<br /><br />I paid about $16 for my shift shaft bushing tool, and the bushing was very easy to remove. I ended up having to get a shop to pull my propshaft and bearing carrier (1 hour labor, heat required, corrosion builds up nicely on a 40 year old motor). Once that was out, the propshaft seals were easy. The driveshaft seals are very easy to get to. If the shafts are scored or pitted, but not too badly, you should be able to resurface them using a speedi-sleeve. I believe it cost about $50 for all my seals, plus $30 for the speedi-sleeve for the driveshaft ( Grubb's Marine sells these). I didn't purchase the bearing carrier ring tool (ended up just drilling and breaking it out) and having the shop pull the propshaft and carrier.<br /><br />By disassembling things to replace the propshaft seals, it will afford you the opportunity to inspect the gears. That will be the true indication if the lower unit is worth resealing.