1976 Mercury 500 Problems

[reelfishin]

I was given a '76 Mercury 500 50 HP over the winter, the former owner told me that he had given up on it since no one could get it to run. He gave me several repair receipts for various parts and estimates, there are three for replacing the igition stator, and one that says the motor needs a new stator which is the most recent. According to the former owner, none of the repairs had gotten the engine running. He also said that the last time that it ran, it wouldn't charge the battery. He gave me a bag of old what looks to be the old ignition triggers.
I hung it on a boat here so I could mess with it for now and I did a compression check first, just to be sure I had a healthy motor, and it's got 150psi per cylinder, so that part should be fine.
One thing I did notice is that several of the wire ends on the box are a little green and the insulation is pulled back a ways on the wires. the motor otherwise is super clean looking, it came from freshwater, so it's not all pitted. It hasn't run at this point now in the last ten years.
After hearing about the charging problem, I am wondering if maybe they have been changine the wrong 'stator'?

I called a few local shops, but none were familar with the older motors, they all said trash it and buy a new motor. I had one of these years ago and it was a great motor that gave me no problems for the 15 or so years I owned it, so I'd like to get this one back in shape. Is there a simple test to check both the ignition and charging circuits?
The harness looks bad enough to warrant replacement in my opinion, I can't believe that any of the shops the old owner took this to didn't mention the condition of the wire ends. My guess is there has to be resistance there, if not broken wires. I tried to find a good harness, but have had no luck, a new one is too expensive to just take a guess and try it. How likely is a bad stator?
Judging by overall appearance and compression, this motor hasn't had much use, so I am suspicious of it having a bad stator, I am leaning more towards a loose or corroded wire or harness?
I did have spark at one point, but it went away after only a short burst, but I have not idea if it was because I was messing with the wires, or just by chance, I haven't been able to get any reaction again by wiggling the wires.


It's also got a stuck prop, its probably never been off, I have it soaking for now, but that rarely works. Does anyone know of a prop puller that will fit these?

 

[timmathis]

Re: 1976 Mercury 500 Problems

1.Do you have a manual? If not and you are going to work on it you will need one.
2. Now you will have to do some troubleshooting. Is it getting spark at the plugs? is it getting fuel?
You can go to www.outboardparts.com and read a good troubleshooting guide. Click on mercury then click on troubleshooting then click on print guide.
Also I don't think a bad stator will keep your model from starting. It just won't charge the battery.
3. With good clean carb's and a good hot spark it should start and run. 150 lbs of compression is real good
you should get many more years out of it in that shape.
4. You can get a wire harness for about $100.00 on ebay if you need one . it is nornal for one that many years old to show some wear and tear. Just make sure you have no shorts in the wires. Good Luck and welcome to iboats, Tim

 

[reelfishin]

Re: 1976 Mercury 500 Problems

I have a manual ordered, should have it in a few days.
I haven't put fuel to it yet, I noticed there was no spark when cranking it for a compression test. The part that gets me is why they kept changing ignition pickups? (Ignition Stator?) There's a bag with several of them, all look like new but have been installed. My guess at this point is that one of the terminal ends or wires are corroded bad enough to cause an intermittent, a few look like they're about to break off. There's not a lot of room to work with the wires, and I don't want to butcher the harness with just crimp on connectors, what I may do is remove it and solder new ends on and replace the wire back enough to get past the corroded conductors. (The larger wires look like corroded battery terminals).
How many years were the same?
Also, this has no power tilt, the boat I'd like to use it on really needs power tilt since the motor is pretty well out of reach from in the boat, can it be added or is an aftermarket kit the only option?

 

[imported_Voyager]

Re: 1976 Mercury 500 Problems

Make certain that the switchbox has a good ground. This item is pricey, and if not well grounded it will fail. The switchbox could be your issue, or cracked flywheel magnets. I'm not sure what the motor acts like when the flywheel magnets get cracked, but this introduced extra magnetic poles that would send odd signals to the brains. It sounds like you have a new stator from your receipts. First order of business is get the wiring fixed, so you're on the right track.

Parts of the wiring of my '82 4 cylinder were in similar condition, insulation turning to chalk, corroded wires. Would you be willing to part with one of the triggers that your have (ignition pickups)?

 

[duff]

Re: 1976 Mercury 500 Problems

replace anything with bad wires. I hade a similar problem on my 79 80hp merc. i had to replace the stator due to bad wires just like what you are discribing. mine was bad it ended up being the wireing harness, stator, trigger, rectifier, mercury switch, and wires to the coils from the switch box. a total rewire. for around 400 i did all the wires and replaced the stator,trigger, switch box, and starter. i think it was worth the time and effort. if you do not need to replace the switch box than dont. but anything with bad wires need to go away.

duff

 

[rustyscrew]

Re: 1976 Mercury 500 Problems

As for the prop...if a puller and soaking doesn't get it. You can resort to heating the prop and melting the hub. See:

http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=29;gtid=1280465

good luck8)

 

[reelfishin]

Re: 1976 ('77?) Mercury 500 Problems

Re: 1976 ('77?) Mercury 500 Problems

I was hoping not to destroy the prop, it's still good, but I need to change pitch since I'd like to put this on a smaller boat. I've had it sitting with the prop facing up for a few months in the garage with PB Blaster soaking in, but no results. I need to come up with some sort of puller that can grab this evenly at three points. I see they list a puller for the Mercruiser drives, but the dealer says they won't work on the smaller outboards?
I'd rather spend the money on a puller than ruin a prop, I'll use the puller sooner or later again, and I am sure it's not the last stuck prop I'll see.

Does anyone know how common the wiring is among the various years of these Merc 50Hp engines? I have called several places that all asked for my model number, each have come back and said they don't list a harness for my motor for some reason. I can't imagine them making so many different harness configurations? The dealer that I called today said my motor is a '77 model not a '76, (4577131), if that matters. I plan to put it on an aluminum boat once I get it straightened out, I figure I'll need a 10.5 x 12P prop on that boat, the prop on this now is only an 8 3/4" x 13P, it looks like a pretty small prop for this motor, but I believe it came off a much larger boat.

What are my options as far a adding power tilt to this?

 

[billybones]

Re: 1976 Mercury 500 Problems

oldmercs.com will tell you all you need and offer you parts you can not find elswhere.

 

[Smig]

Re: 1976 ('77?) Mercury 500 Problems

Re: 1976 ('77?) Mercury 500 Problems

What are my options as far a adding power tilt to this?

You can go with an aftermarket unit like this or you can add Mercury's original two-ram system. It's just a matter of finding all of the parts. I was fortunate and actually found an NOS kit, but paid a lot for it. You can find all of the parts and pieces on ebay or your local outboard salvage yard. Here is a copy of the installation manual that came with my kit - it shows everything you'll need.

There have been many threads about adding trim - you can try the search function (which is kind of broken right now) and you might stumble across a few.

 

[reelfishin]

Re: 1976 Mercury 500 Problems

Is the oem tilt kit still available? That looks like the best bet, how much should I expect to pay?
The CMC kits sell for more than I paid for my whole boat.
Before I'd dump a ton of money in this, I'd find another used outboard that already had power tilt.

Does any other models tilt components fit this? I have the chance to buy a 40hp with power tilt for $100, that's a running motor, but a bit newer and smaller than I prefer to use if posible. I think that motor is a 1981. It ran when last on a boat, about 10 years ago, I know the guy that has it, I helped him carry it in off his boat the last time it ran. If I could use the power tilt off of that, I'd be ahead of the game. A local marina also has a blown 1980 70 hp Mercury that had Power tilt, he told me I could have that for cheap too if I remove it from the boat myself.
I looked at another slightly newer 50 HP, it looked the same under the cover, but was not a "500" model. It was a 4 cylinder and the power head looked nearly identical to mine, but the lower and mid sections were much lighter looking, narrower than mine overall. The cover attached the same but had only one latch or turnbuckle in front, where mine has two. That motor had power tilt, but the motor bracket was nearly twice as wide as mine. My motor bracket is only about 11 inches wide where it hangs on the boat, and mine still has clamp bolts, that one used only bolts, and the whole assembly spanned at least twice the area that mine does. Was the 500 a completely different motor than those that followed only a few years later?

What does one of these motors usually sell for when they are in good shape? It may not be worth my trouble to mess with this?

 

[Smig]

Re: 1976 Mercury 500 Problems

the oem kit isn't available - I got mine off ebay from an old marina that was closing. I spent the money because we cruise very shallow rivers and lakes and they eat props!

As far as I know (and that isn't much!!! I am new to this) there were several different styles and types of tilt units and engine mounting brackets, but I don't know the specifics - there are others here who do, though.

At some point, the 500 was repackaged and they put the word "Classic" in the name, but I don't know the differences. Again, some else may be able to help, or try some searches, it has been discussed. You can also look at one of the on-line parts diagram sites (Bammarine.com, Dougrussel.com) and compare parts.

For value, you can look at NADA.com guides, but in my area, they are not correct for old motors. You can also check ebay and look at completed auctions - there are a lot of motors that sell there.

Good luck
Smig

 

[reelfishin]

Re: 1976 Mercury 500 Problems

I compared my 76-77 500 to a buddies 1981 Mercury 50 HP that's also a 4 cylinder. The power head looks the same as does the prop area, but my mid and lower units are wider, heavier looking, my wrap around engine cover secures with two latch/turnbuckles vs. only one on the newer motor and his front cover plate is less ornamental. His has power tilt, but the motor bracket is a lot wider and looks nearly double the size of mine. His controls are nearly identical.
I have seen a lot of used motors for sale, and have not yet seen a power tilt or trim Merc for sale. It seems all the other makes are almost always power. This motor really caught my eye since its so clean looking, most of the motors I see here have severe salt damage. What metal is the inner hub and prop shaft made of that they seize up so often?

I have been looking for a larger outboard for another boat, something in the 100hp range with power tilt, and haven't seen much under $600, and they look rough. New is just not in the budget.