Mercury 500...need some info

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ivesterjamie

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Joined
Dec 29, 2002
Messages
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I just bought my friends merc 500 along with a 15' Venture. I know the motor runs fairly good (we had it out on Lanier running around 25mph by gps). The problem is, it takes it a long time to get up to speed and doesn't seem like it really revs up like it should. It had new plugs put in before the last few times we ran it, but I don't know their condition now. Inside the cover, there seems to be some kinda fluid like maybe wd40 on everything. I know I'll need to replace most of the hoses. Good thing is, It came with a brand new steering cable kit in the box still and I got it cheap. Also, I can't locate the serial number to buy a part. He somehow broke the "tab" on the front of the engine that the steering arm bolts to. I see this part looks like it can be removed by loosening a couple bolts. I'm no mechanic, but I have a pretty good background and want to do it all myself. I just need a little advice. I know the boat and motor are probably from the 70's, and I think this may be the serial number if anyone has any ideas 14403255. From what little info I have to reference it to, i'm thinking its a 1976. Anyone have any ideas on the motor as well as replacing that steering tab. I think I saw somewhere that it was maybe $10, but the diagram was unclear so I can't be sure it was the right part.
 
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ivesterjamie

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Dec 29, 2002
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9
Re: Mercury 500...need some info

also, I haven't taken a close look at the prop, but I know he replaced it so that could be a problem I suppose. I'm not sure how to tell anything about the prop either though. As far as I know, the motor hasnt had anything done to it in a long time either as far as cleaning the carb,etc. I haven't ever really rebuilt a carb, but I can take anything apart and rebuild it. I want to spend as little as I have to on the motor right now. I just want it to be reliable and not do itself any damage. I primarily will be using it to shuttle myself over to a few scuba diving spots is all. Also, anyone have a guess as to the top speed of this combo when its running right and no load? The boat seems to be fairly light. 15'6" Venture/mid 70's merc 500 50 HP. Also, I want to install a tach and I see on the motor that I should only use a Quicksilver tach. It also has the Thunderbolt ignition and I see it says "fuel-jeweled super thunderbolt"
 
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Bear

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Mar 1, 2001
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1,627
Re: Mercury 500...need some info

500 (50,0) 2514919 - 2736806 <br />1969 <br />4 cyl<br /> :)
 
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ivesterjamie

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Dec 29, 2002
Messages
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Re: Mercury 500...need some info

thanks bear, I just found that out earlier today. Now if I can just get everything else straightened out.
 
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Hooty

Rear Admiral
Joined
Oct 2, 2001
Messages
4,496
Re: Mercury 500...need some info

Hey Jamie,<br />First, if you plan on working on your engine yourself, you're gonna need a service manual. You can order an aftermarket manual by clicking the "Service Manual" icon in the lower lefthand corner of this page or a factory manual from your Mercury dealer.<br />You're going to have to do a compression check on the engine first. Do that then get back to us and tell us what ya got and we can go from there.<br /><br />c/6<br /><br />Hooty
 
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steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Mercury 500...need some info

Jamie,<br /> Reprint factory owners and service manuals are<br />available at:Grubbs Marine www.oldmercs.com.<br /> Im no expert but wonder if that coating under <br />the cover is from a bad upper seal?<br /> Probably would be wetter up under the fly<br />wheel.<br /> I have a 1965 500 On a 17ft utility Not real<br />heavy.Bare boat about 350+ pounds. Im guessing it does 35 to 40 mph.<br /> Another site that could be a help.<br />Johns Old Mercury Web Site at: www.pfs-ware.com<br /> Lots of links and a good forum.<br /> If the motor has been sitting around alot<br /> You should go through the fuel system, tank to<br /> carbs, With special attention to cleanimg.<br /> If you dont know when the water pump impeller was changed last most would change it out.<br /> Check ebay for after market manuals also they<br />may have them at the library.<br /> Good luck.
 
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ivesterjamie

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Dec 29, 2002
Messages
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Re: Mercury 500...need some info

we changed the impeller last summer, and the stuff on the engine isn't oil, upon closer inspection, it is definately just a large dose of wd40 sprayed on it. The block and head oddly look like they could be brand new. I think the guy that had it last had done some tinkering with the carb adjustments, so cleaning and adjusting the carb is my first goal followed by figuring out what pitch prop the previous owner put on it. (I know he changed it when he bought it and I'm not sure its the right pitch). The motor runs strong and I really feel like it has good compression. I don't have any way to test the compression myself, but I'm trying to do as much of the work as I can. I'm not really familiar with what I need and the procedure for checking compression either. Something along the lines of a pressure guage in the spark plug hole, right? Service manual is on the way also...
 
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rdmcphe

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Joined
Jan 11, 2002
Messages
17
Re: Mercury 500...need some info

I have a 1980 Merc 50 (4-cyl) on a 15.5' fiberglass runabout. I normally cruise at about 18 knots (21 mph) at 4200 RPM. At WOT it does 24.5 knots (28 mph) at 5400 RPM. <br /><br />The speed measurements were done with a GPS. The motor has a 14" pitch prop. <br /><br />I hope this helps.<br /><br />Russell
 
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ivesterjamie

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Joined
Dec 29, 2002
Messages
9
Re: Mercury 500...need some info

yeah, I everything I'm hearing is helping tremendously guys. I think I need to get a tiny tach and see exactly what the motor is turning. Anyone know of any sites that list setup procedures for the shift and throttle linkages? Everything is off the boat now and I basically know where everything goes, but just wanted to know if there were any specific setup procedures. I'm getting the carb cleaned up and repairing/replacing the wires/hoses to the engine. I have to do some fiberglassing and then I'm in business. I also built a 12' johnboat that I need a motor for if anyone has one for sale. Thanks again
 
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Jim@KSC

Petty Officer 3rd Class
Joined
Nov 1, 2002
Messages
89
Re: Mercury 500...need some info

ivesterjamie -<br /><br />You said...<br />"it takes it a long time to get up to speed and doesn't seem like it really revs up like it should".<br /><br />I reread your post and couldn't determine if thhis is a new condition or if it has always existed.<br /><br />After you get through looking at the engine, as posted above, search this board and find links to prop selection, to see if you aren't potentially over-propped. If the pitch is too great, and/or the diameter larger than you need, it would produce exactly those symptoms.<br /><br />Good luck!
 
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