1985 Mercury 75hp-known issues?

[mattjenna]

Writing from Sydney, Australia and this seems to be one of the best boating forums on the net and particularly on Mercury motors.<br /><br />Looking at purchasing an 85' Mercury 2 stroke 3 cyl 75hp long shaft with tilt and trim for a 16 feet half cabin-replacing a dead 60hp 82' Johnson 2 cyl 2 stroke.<br /><br />One of my local marine mechanics commented that the 75hp Mercury wasn't a great motor and was problematic-called it a black anchor.<br /><br />Apparently this motor has had a recent major service replaced impeller has 120psi compression in all cylinders and is running well.<br /><br />Wondering if anyone here has knowledge of these motors and any known issues?<br /><br />In advance, thank you very much for any input.<br /><br />Regards<br />Matt

 

[Dunaruna]

Re: 1985 Mercury 75hp-known issues?

Hi Matt, welcome to iboats!!<br /><br />It's the 'ford/holden' syndrome. You either love 'um, or hate 'um.<br /><br />The 'black anchor' tag is from someone who is a jonnyrude fan or susie fan - comprende?<br /><br />Off topic, you on dialup or broadband?<br /><br />Aldo

 

[mattjenna]

Re: 1985 Mercury 75hp-known issues?

Mate,<br /><br />I'm on broadband.<br /><br />Don't get the johhnjy rude allusion?<br /><br />So, any kown issues on this motor? Or mercs of that era generally?<br /><br />Thanks<br />Matt

 

[andy6374]

Re: 1985 Mercury 75hp-known issues?

Matt-<br />He was just refering to the fact that people who love merc's talk crap about jonnyrudes and vise versa.<br /><br />I am sure you'll love the engine. Keep the fuel system up to par (ie clean carbs, good fuel pump....) and change out the impeller every other season and the engine will last forever.

 

[andy6374]

Re: 1985 Mercury 75hp-known issues?

Question for the pros, however it may or may not apply here:<br /><br />What year and model Mercs were notorious for overheating due to steam bubbles in the top of the block. I know the fix was to relocate the tell-tale to the top of the block.<br /><br />Just making sure Matt is ok.

 

[mattjenna]

Re: 1985 Mercury 75hp-known issues?

I'm far more familair with Johnsons /Evinrude having had those and mates who have also had them.<br /><br />A few apparent Merc problems have been pointed out as:<br /><br />*Poor quality wiring("dissolves") <br />*Some of the motors don't use a head as such, the combustion chamber is built in to the block, with a basic water jacket. Claims this is a weak point. <br />*Complex water jacket/exhaust designs in the bigger motors. <br /><br />Not forgetting I'm talking about a mid 80's 3cyl 2 stroke 75hp motor and NOT a new Merc.<br /><br />Just don't want to buy a lemon with all the associaetd hassles-too financially challenged ;-)-hence posting here.<br /><br />Thanks<br /><br />Matt

 

[Clams Canino]

Re: 1985 Mercury 75hp-known issues?

Overall, The 74hp four was a reliable motor, though perhaps not as slick as it's little 3 cylinder cousin or it's 6 cylinder big brother.<br /><br />Make sure the carbs are clean and the max-advance is 21 degrees. <br /><br />-W

 

[mattjenna]

Re: 1985 Mercury 75hp-known issues?

CC,<br /><br />I understand that this is the 3cyl model.<br /><br />What do you mean "as slick" please?<br /><br />Matt

 

[Clams Canino]

Re: 1985 Mercury 75hp-known issues?

Just that 2 strokes seem to run a but smoother in multiples of three cylinders. <br /><br />If it's a 75hp triple it may be a year or two newer than 1985. That's OK too.<br /><br />-W

 

[Laddies]

Re: 1985 Mercury 75hp-known issues?

We used the 75HP 3 cyls. for rental and the only problems we had was after a year or two the stators went out and had to be replace, we used Rapair stators and that was the end of the problems. Mercury stators were junk

 

[mattjenna]

Re: 1985 Mercury 75hp-known issues?

Originally posted by Clams Canino:<br /> Just that 2 strokes seem to run a but smoother in multiples of three cylinders. <br /><br />If it's a 75hp triple it may be a year or two newer than 1985. That's OK too.<br />-W

Is that correct? they run smoother in multiples of 3? Never heard that before.<br /><br />Matt

 

[mattjenna]

Re: 1985 Mercury 75hp-known issues?

Originally posted by Laddies:<br /> We used the 75HP 3 cyls. for rental and the only problems we had was after a year or two the stators went out and had to be replace, we used Rapair stators and that was the end of the problems. Mercury stators were junk

Laddies-so all in all a reliable motor?<br /><br />I understand the stator is part of the ignition system, is that correct? <br /><br />Matt

 

[andy6374]

Re: 1985 Mercury 75hp-known issues?

Yes reliable.<br /><br />The stator is part of the ignition system.<br /><br />Stator and switchbox failure is common and like Laddies said replace em with CDI/Rapair instead of merc.

 

[mattjenna]

Re: 1985 Mercury 75hp-known issues?

CORRECTION-I am now told it is a 4 cylinder-my bad, I thought the bloke said it was a 3 cylinder.<br /><br />It's a 'Brown Band' - if that's any help on advising me.<br /><br />Thanks<br />Matt

 

[mattjenna]

Re: 1985 Mercury 75hp-known issues?

THIS TOPIC-FOR ME ANYWAY-SHOULD BE CLOSED.<br /><br />Sorry all Merc heads-going with a Johnson-thank you SO MUCH for all replies.<br /><br />Matt

 

[Clams Canino]

Re: 1985 Mercury 75hp-known issues?

Suit yourself....<br /><br />I'd rather have a small Merc than a small Johnson. <br /><br />-W

 

[mattjenna]

Re: 1985 Mercury 75hp-known issues?

Originally posted by Clams Canino:<br /> Suit yourself....<br /><br />I'd rather have a small Merc than a small Johnson. <br /><br />-W

Why?<br /><br />Matt

 

[RiverKnight]

Re: 1985 Mercury 75hp-known issues?

I have this same motor , I think u are right it is a 4 cylinder , right now I'm having probs with it, runs good for about 30 minutes then after u stop and cut it off . When u restart it cranks fine but as u go to take off it bogs and stalls . Will recrank and idile fine but have to play with it to get it to take the gas without stalling.Can anyone help me with this issue. It's an 85 mercury 75 hp.