Merc 500 Revival

[spamn]

So I got a really good deal on a 1978 Mercury 500, 4cyl, 50 hp outboard. I got had an old gutted out boat and trailer with this engine. I just wanted the engine since my boat has a out of service 1972 Merc 402. He wanted it gone so he offered it all for $100. I purchased it of course and then sold the boat and trailer on craigslist for $200. Essentially, I got this engine for a profit of $100. Not bad, right?

I brought it home and put it on the boat. I popped the cover and it looks extremely CLEAN as if only a few years old. Not 30+. The guy had no idea what condition it was in or when it last ran. I saw right away the the starter solenoid was busted up. I ordered a new one for $10. Hooked up my controls, battery, and gas and attempted to fire it up.

It started right up in a barrel of water. I ran it for less than a minute as just a test. Now... I know very very little about outboards. What do I need to do before I attempt to put this in water? The telltale had a stream coming from it, but it seemed not enough for me. I do not know what it should be though. I never put the engine in gear either. Not sure if that matters for telltale output. I'd like to test the engine in the water, but what can I look for prior to doing so? Do I need to rip the lower unit off and replace the impeller? How can I tell if the water pump is good? I'm already $90 in profit in this engine so ordering an impeller and what not as precaution wouldn't be horrible.

Any advice on what to check or replace would be appreciated.

Thanks in advance
Sam

 

[spamn]

Re: Merc 500 Revival

Not sure if I have the controls hooked up wrong but when I try to fire it up, it seems to run for a second in neutral and then almost as if it's going into gear on it own.. it revs pretty high and the barrel gets a nice amount of water tossed up out of it. As soon as that happens, I turn it off. I don't want to fire it up anymore before further investigation. I have a feeling I have a good engine but can turn it into a bad engine pretty quickly by running it without checking something. The throttle cable appears to be hooked up with everything centered and the throttle not pushed forward or back. Here's a picture, but I doubt it helps.


Being a boat novice, I'm not even sure if I'm starting it correctly. The Mercury controls have two levers. A large one towards the inside that controls the gears. Straight up being neutral and then a smaller lever that is outboard that I believe is the idle lever. When starting, what position should this be in? What position when running? I was told both straight up to start and then throw the small lever all the way back when moving.

 

[merc850]

Re: Merc 500 Revival

Yes go with a new impeller and check the gear lube before using. The inside lever is "fast idle" raise it so it's sticking up, when engine starts lower it and keep it lowered. You can check the cables by moving shift handle - it should shift into gear first then as you push the lever farther forward the throttle should move. I am assuming that this is the single lever MerControl.

 

[spamn]

Re: Merc 500 Revival

Not sure what you mean by single lever. It's an old MerControl with the two levers. One large and one small. I'm assuming throttle/gear and fast idle. It also had an electic choke button but not sure if that even works with this motor or how to make it work. I ordered a new impeller for my 402 and just looked online to see that they are the same part number. Looks like I will take the lower unit off and check it out. If it's bad, I already have an impeller laying around to fix it. I have some gear oil too.

I think I boogered up my controls when connecting to the engine. I need to take a better look at them. Again, I have zero experience with outboards but know a good amount about cars so some of this is common sense mechanics. Now if only I wasn't in the miltary and have a 2 year old kiddo, maybe I would have time to work on it more..

Hopefully this weekend I can get to that lower unit and the controls. I'd like to have the boat up by March for the pre spawn.

Thanks again for the response.

 

[SeaKaye12]

Re: Merc 500 Revival

Hey Spamn....

You're on the right track. You can read one of the FAQ posts here to get a rundown on all that you should do:
http://forums.iboats.com/showthread.php?t=158086

You need to be sure that she's getting water for cooling and oil for lubrication.The fuel needs to be mixed 50:1 with 2-stroke outboard oil. At this point I would test the compression to verify that you do indeed have a motor worth investing your time and $$$ into.

Get good results there and then you can proceed with the other items in the FAQ.

From what I know; those are very good engines.

Chuck

 

[spamn]

Re: Merc 500 Revival

How exactly do you compression check and can I use an automotive tester like one from Auto Zone?

 

[carholme]

Re: Merc 500 Revival

spamn;

Compression check:

http://forums.iboats.com/showthread.php?t=391323


Gerry

 

[spamn]

Re: Merc 500 Revival

Going to get a compression tester in a bit. In the mean time, I popped the lower unit off and of course, the impeller was toast. I also found it odd that there was very little lubricant and it was also very thick. No evidence of metal shards or water though, so that's good.


I also found an odd looking metal ring that was around the top of the water pump. See picture.. Not sure where it's supposed to be but it was around the drive shaft and laying on top of the water pump. It's metal and like a tightly coiled spring because it stretches. Any info on what this may be would be appreciated.


Lastly, I cannot get the water pump or impeller off because the drive shaft has a seal or something on the top of it that blocks removal. Also see picture.


I already have complete lower unit parts laying around from my 402 so I'm going to replace the impeller, put in new gaskets, and fill it back up with lube. Water pump looks fine to me, but maybe I'm not looking for the right things.

Exhaust tube seal and what not look fine too.

 

[carholme]

Re: Merc 500 Revival

spamn;

What is the s/n of your engine and we can get you a complete parts listing.

Thr rubber ring around the shaft on top of the water pump in the second picture is just a slinger which prevents crud from getting into the waterpump top seal.

The piece you are talking about in the third picture looks like the lube seal which will make sense when you see the parts list.

Gerry

 

[spamn]

Re: Merc 500 Revival

Not the slinger, the metal ring laying on top of the water pump. In the picture its above the pump and below the slinger. It's not supposed to be there. It looks like it was supposed to be attached somewhere up top and came loose and fell down around the drive shaft.

As for the third picture, it was a seal. Even though vice grips seem to be the answer for everything.. they are not. I got them off but they are roughed up. Thinking they were like $1.00 I went to order new ones but they are like $12 and $6. Nothing in this hobby is cheap, huh?

As far as the lower unit goes, it looks like I have everything just about back together. Just need to order those new seals. I guess while I wait for them I can get on the compression test. Having the lower unit off would have no affect on the test, correct?

S/N 4965581

 

[spamn]

Re: Merc 500 Revival

Also forgot to mention that the impeller will not slide all of the way down the driveshaft. It stops about a half inch or so above the impeller key. It should slide right down to the key, correct? I don't want to force it. I ordered the correct one. Just confirmed with the store.

 

[merc850]

Re: Merc 500 Revival

That metal ring looks like a seal spring that might have fallen out of a lower driveshaft seal, you'll have to look into the lower bearing cap in the powerhead to be sure.

 

[carholme]

Re: Merc 500 Revival

Here is the parts listing and for the gearcase for your s/n, use Serial Number Group 7.

http://www.crowleymarine.com/mercury-outboard/474.cfm

 

[spamn]

Re: Merc 500 Revival

Thanks for the info... Looks like this little circular spring dealy is going to make me do some work. Being around the driveshaft it could have only came from so many places. I peered up the drive shaft housing (the middle section of the motor. I think that's what it's called) and can see where the drive shaft enters the powerhead. It's hard to tell but it looks like the spring attaches at the bottom. Not sure if that's what you were talking about "merc850". Unfortuneatly the only way to actually get a hand up by there is to remove the power head. Looks like I need to buy more gaskets once again. I should have time this weekend to do that and compression check. I'm willing to do just about anything except for open that block. So fingers crossed for good compression.

Lastly, are 49A and 49B the seals that go on top of the drive shaft (the ones I need to replace due to removal with vice grips)? I think so but that diagram makes it look like they go below the water pump.

Noone ever had trouble getting an impeller to go all the way down a driveshaft to the key?

Thanks again everyone for the help.

 

[merc850]

Re: Merc 500 Revival

Never had the impeller not go down the shaft; don't know the answer. If you're going to check the lower seals you don't have to split the block- just loosen the 2 crankcase bolts at the bottom of the crankcase, remove the 3(4) bolts that hold the lower cap on then get some smaller bolts to fit into the little holes in the cap. Set up a puller with those little bolts all the way into the little holes, make sure that they are all the same height and then thread the puller bolt into the crankshaft end.
Turn the puller bolt and it will pull the cap off, I would replace both seals and the Oring.
The seals should have Loctite on their metal frames when installed and grease on their lips, put Perfect Seal or Permatex on the Oring area and some oil to help slide the bearing cap into place.
Push the cap back in (make sure that the bolt holes are lined up) and you can lightly tap it in for final seating.
Replace the cap bolts and tighten the crankcase bolts. Make sure to reinstall any shims that have been installed.

 

[spamn]

Re: Merc 500 Revival

Bottom of cap with random seal spring thingy that was found around driveshaft and on top of water pump
Top of cap with random seal spring thingy

I pulled the cap. How do you recommend getting the seals out and where exactly does that piece go? Before I rip into it and pull bearings out, are we positive that this thing came from there? I don't see where else it could have come from though. Without taking it apart, there are many places that look like it may go.

 

[merc850]

Re: Merc 500 Revival

You should be able to see the seal the one closest to the bottom would be the one that seems most likely, look for a spring around the lips.How is the bearing- it should turn easily without any catching and no play. If you're going to replace the seals/bearing you have to press the bearing out from the bottom, a dealer can do this and sell you the seals etc.

 

[spamn]

Re: Merc 500 Revival

Bearings roll smooth.

I think I'm starting to understand. This spring dealy is PART of the oil seal? I've been racking my brain looking online and through my Seloc manual to locate this part to no avail. I can't really see anything about the seals without removing the bearings. If that's the case, is it best to replace both seals and the O ring while I have it out? Doesn't seem necessary to replace the bearing unless they get messed up on removal.

 

[merc850]

Re: Merc 500 Revival

You're correct, I would replace the seals, Oring and bearing just to be safe, but if you don't want new bearings check the old one after removal to see if it is still good. A tool (maybe a bolt, head first) is needed that fits onto the inner race for pushing out the bearing.

 

[spamn]

Re: Merc 500 Revival

Thanks for all the help. I was able to get the bearing and seals out by boiling the end cap in a pot of water (no torch here). Once it expanded a bit I gently tapped the bearing out. The seals wouldn't come out so gently, but they were shot anyway. I was able to find that the seals contained the "spring dealy" that I have been wondering about. One seal was missing it.

I'll order new seals and O ring and go from there. The bearings seem fine still, but I may replace them just to do so while they are out.

Can I check the compression while the powerhead is off? I got a tester. Some instructions say to test while the engine is warm which is not possible in it's current condition. Is there a way to test now or do I need to wait until I get it put back together?