63 Merc 850 questions

[JasonJ]

I bought a 63 Mercury 85 horse inline six last month, and it has been running good, but I have a few questions. I have been running it at 40:1, do I need to run it at 50:1? I have noticed that it seeps a bit of oil/fuel mix in a few spots while running, just kind of bubbles out, at the mating surface between the block and the plate that the carbs are bolted to. Power and economy doesn't seem to suffer, and all the plugs are about the same color-wise, but I feel like I should fix it. Do I need to fix it, or should I just live with the seepage and clean the engine once in awhile?. Lastly, the engine is charging, producing about 12 volts from the rectifier, but when I disconnect the battery ground, it stops. Shouldn't it still run when the battery is disconnected?<br /><br />Jason J

 

[River Rat 01]

Re: 63 Merc 850 questions

My opinion on the seepage is yes, fix it. It has been my expeirence with 2 strokes that you want everything sealed up, that's supposed to be. Sorry I can't help with the rest. Good Luck<br /><br /> RR01

 

[Chinewalker]

Re: 63 Merc 850 questions

Hi Jason,<br /> Definitely fix the cracnkcase seepage. You're losing crankcase compression with that and in effect, losing power. Crankcase compression is as important as cylinder compression, and often overlooked. It's also a fire hazard. You can get a manual for it from www.oldmercs.com .<br />- Scott

 

[JB]

Re: 63 Merc 850 questions

Howdy, Jason. I agree with the fellows above on keeping the crankcase tight.<br /><br />You need to give us more info on the electrical issue. If your engine is only making 12v it is not charging. Are you reading a voltmeter? Your battery should be 12.6v when fully charged, and the alternator in your engine should produce 13.5 to 14.5v when charging. Let us know what you are looking at and what you see.<br /><br />Red sky at night. . .<br />JB

 

[JasonJ]

Re: 63 Merc 850 questions

I went ahead and ordered a service manual for the Merc, I've been looking for one anyway. Yeah, the rectifier shows 12 volts, I am assuming it is just showing the battery voltage. The two leads from the generator do show A/C voltage, I may just do the same fix that I did on my Homelite 55, getting a $3.00 part from Radioshack to replace the rectifier, mount it on a small heat sink, and go. The Homelite is kicking out almost 14 volts at idle with that part, and it is much smaller (can't remember what it is called off-hand). I do want to fix the case leak, just because it should be fixed. Anyone ever do this? Is there a gasket, or a sealant that is used?

 

[ODDD1]

Re: 63 Merc 850 questions

Jason, I can probably give you some insight on your old merc...these particular motors did not have anything but a thin layer of gasket sealer between the crankcase cover and the cyl block....after 30+ years, it washes out and leaks...how much is leaking out? not enough to affect the operation of the motor...and taking the motor apart to repair is kinda like poking a bear with a stick...your just askin for more trouble...<br />the finned rectifier that charges the battery is the old selenium plate style...pathetic when new, and junk now...replace it with a bridge rectifier, and quit unhooking the battery when the motors runnin! you will just wreck the new one....

 

[JasonJ]

Re: 63 Merc 850 questions

Thanks ODDD1, thats something that has been on my mind the whole time. I have extensive mechanical knowledge, but it is all automotive. I have no fear of tearing into an engine, I have rebuild many, even a few whole vehicles, but two stroke outboards are sort of new to me, and while I hate this leak and my impulse is to fix it, it is hard to justify it when the motor fires right up every time and my little 17 footer hauls pretty good butt with it. I am afraid that, like you said, by attempting to fix one thing, I'll end up causing more problems. I'll just see how it goes for now. Yeah, I'll get the bridge rectifier and that will fix that. No one answered my fuel/oil question: Should I run it at 50:1, or is there a better ratio? Anyway, thanx everyone for your help...While I am not a novice boater, this particular motor is new to me, always had the Homelite 55 4 cycle, thats a whole different animal altogether....<br /><br />Jason J

 

[Chinewalker]

Re: 63 Merc 850 questions

Hi Jason,<br /> I still feel should take care of the seepage issue, although it's probably something I'd save to be a winter project. It's only going to get worse and it really isn't that big a deal to fix. You'll only be doing a partial teardown and the pistons and crank won't have to come out. For a beginner using a manual it's probably a two evening job. Just mark your wires with tape as to were they go. Also a good idea to replace the webbed timing belt (mark the flywheel and belt pulley so you can line thm up again!).<br /> As for fuel/oil ratio, 50:1 is fine for most older Mercs back to about 1960, exceptions being the old racing motors.<br />- Scott

 

[ODDD1]

Re: 63 Merc 850 questions

Jason, if you use good oil you can run 50:1 with no worries....as to your background, have you ever used Loctites Wick n Lock??<br /> Hint Hint........

 

[JasonJ]

Re: 63 Merc 850 questions

I have never used wick n lock, but I think I see where you are going with this. I have the feeling that I'll end up doing some good bear pokin' and tear into it and fix it right, but your hint is very intrigueing, I might try it, it can't make it any worse. The $3.00 bridge rectifier works like a champ, it charges like crazy. I had to use my boat this morning to go do a pest control job out on an island we have on the lake, and I thought I would give the manual pull-start a try. I have pulled it before, and about had a hernia. Six cylinders is a lot to try to pull, but ****ed if it didn't fire up after a couple pulls. I was amazed. Once warm, I could just barely pull the cord and it started right up. Good to know. Anyway, because it looks like I would have to pull the powerhead to fix my leak, I may postpone it until the season is done. I'll see for sure once I get my service manual....