1975 55HP-Worth it or no?

I am considering buying a project motor to fool around with this winter. It is a 1975 55 HP 500 (serial #414371. Before I plunk down the cash I was hoping you good folks could help me out. Are parts available for this vintage? And of course first part I would need is a service manual, hopefull OEM. Thanx in advance for any help/advice y'all might have.

Re: 1975 55HP-Worth it or no?

You can look to see what parts are available on this website (up at the top left). Also mercruiserparts.com (aka BAM Marine) and maxrules.com have a good selection. Look at the photo gallery at oldmercs.com before you start on your project...just to give you some inspiration.

Re: 1975 55HP-Worth it or no?

Hi Ralphy,<br /><br />I've been working over a '77 85 HP...and it certainly seems that most any part I would need for that is readily available...some from Mercury themselves...a lot from generic folks like Sierra and Rapair CDI...and some from both. Manuals are available also. I have a Clymer Manual. Don't waste your money on a generic like that...get the genuine Marcury manual.<br /><br />Fortunatly for me...my engine is pretty much un-molested. Nobody ever worked on it before me so I don't have to worry about some screw-ups or wrong parts installed by somebody. <br /><br />Good luck with your winter project!<br /><br />Chuck

Re: 1975 55HP-Worth it or no?

Thanx for the quick response KI. I did check the BAM site and it looks like basic items are still available, but to be honest this would be the first merc I have owned (if I make the buy decision). Maybe if I post what the seller has told me of the problems it might help.<br /><br />"The lower unit needs new seals and the engine seems to be getting water into the lower two cylinders. I have replaced the upper and lower exhaust gaskets, rebuilt the carbs and re-worked the wiring. It starts but does not have any power and requires the spark advance lever in the up poition in order to keep the motor running. I have not messed with it for over a year."<br /><br />He also gave me Compression #'s of<br />#1-118 psi 2-115 psi 3-115 psi 4-115 psi<br /><br />My initial thought was the water in cylinders would be head gasket, but with those compression #'s seems like that would rule out that idea. Any thoughts?

Re: 1975 55HP-Worth it or no?

They're great motors with lots of power. The only annoyance is that they use a discontinued distributor cap and rotor. I've almost used up all the caps and rotors in the local marine salvage yard and am not sure what I'll do when they run out. I think oldmercs.com sells a replacement cap and rotor but they're like $95 each.<br />They don't have a head gasket, I'd take another look at the exhaust gasket.<br />Eric

Re: 1975 55HP-Worth it or no?

Thanx for the response Eric. No head gasket huh? Interesting. Well since it is a bit of a drive from BC to Texas, I'm bettin you havent used up all the distributor caps and rotors from down this away yet Any other opinions on the odds of successful rescue of this engine. I can get it with a 1975 Bass boat w/trailer. Whole rig for $300. Boat is in good shape for its age. Gelcoat faded out but structurally sound.

Re: 1975 55HP-Worth it or no?

Sounds like a deal as long as you don't mind buying someone else's headache with that motor. It could be anything from an easy fix to a huge project. That motor's a 50hp btw, not 55.<br />Eric

Re: 1975 55HP-Worth it or no?

Thanx for that response Eric. Seller says it was a 55 hp but in my research nothing I came up with showed a 55 hp. Kinda happy that you verified that as it makes a lot more parts available

Re: 1975 55HP-Worth it or no?

Info about your motor: http://www.oldmercs.com/197476Merc500.htm

Re: 1975 55HP-Worth it or no?

Wow, thanx KI!! Great help and looks like all the basics are readily available. My only concern at this point is "the engine seems to be getting water into the lower two cylinders."<br />Owner says he replaced exhaust gaskets, any ideas on where else it could be getting water?<br /><br />BTW SeaKaye, didnt mean to slight you. Appreciate your posting and if I take the plunge will certainly be asking more questions of you.

Re: 1975 55HP-Worth it or no?

Would a bad cylinder block water jacket gasket allow water into the cylinders? I've never seen it fail, but in theory it might allow water in through the lower inspection plate.<br />Eric