replacing a 40hp merc with a 60hp merc...

[Maddoxsdaddy]

I've got a 1979 merc 40hp thats been a pain since purchase last year. I've decided to replace the motor. I've found a 1988 60hp merc 3cyl 2 carb for a VERY reasonable price ($300.00). I do have a couple of reliability questions though. The 60hp is oil injected but the seller is using pre mixed fuel instead of the oil injection system... Is this a problem? I've heard of oil injections for this motor to have a few problems... can anyone elaborate before i go jumping into this?

Thanks...

 

[mthieme]

Re: replacing a 40hp merc with a 60hp merc...

I would not let this sway your decision considering the price. I would be more concerned about compression and all the rubber parts.
I have two Merc 40's of similar vintage - I can help relieve you of yours.

 

[tashasdaddy]

Re: replacing a 40hp merc with a 60hp merc...

get the controls with it. wiring harnesses on mercs, changed every couple of years. i prefer to premix my fuel.

BUYING A USED MOTOR

overall condition, condition of the place you are buying it from, usually tells you how they care for things. compression 100 + psi, and within 10% of each other, good strong blue spark, no water in the lower unit oil. look for discolored paint, (sign of over heat at
one time, also scarred up bolts, as why. have them start it. if they fail to put it in a barrell or tank, or on muffs, or in the water, to start it they don't know what they are doing. best yet is to take it for a 30 min to 1 hour test run. also if remote controlled motor, the controls should come with it.

 

[Maddoxsdaddy]

Re: replacing a 40hp merc with a 60hp merc...

Unfortunately, controls do not come with... It is off the boat and the controls are already hooked up to the sellers new motor. I have the original controls with my 40hp. Can these be used with the 60? Another thing... the 60 has tilt/trim but the switch for it stays on the sellers boat because it is a control mounted switch so i'm guessing i'll need to find an aftermarket switch in order to use the trim/tilt... Or would i be better off getting newer controls with the switch built in? The shop i use for service is advising not to swap my 40 for the 60 because the 60 is still an older motor (yet 10 yreas newer than the 40) that is bound to have issues and i would still be sinking money into it just like i am with the 40...

 

[Maddoxsdaddy]

Re: replacing a 40hp merc with a 60hp merc...

Also... according to the seller, the 60 was on a 21 foot pontoon, ran fine, and was just selling because he found a newer motor. I'm on a tight budget when it comes to fixing things so i need to really take care and make sure the 60 is ok. The motor is currently on a stand. The best I can do is hook up a battery and fuel to run it with some muffs on, but that won't tell me a thing about how the motor handles a load... of course its only going on a 17' alumacraft (rated for a 75) so there's not anywhere near as much of a load as a 21 foot pontoon. I'll use all of your tips when checking the motor out this Friday. I just don't have a way to check compression.

 

[mthieme]

Re: replacing a 40hp merc with a 60hp merc...

Your controls should work fine on the 60 hp.
Not sure about the external wiring harness. Does the '79 40hp still come in on the side? The 60 should go in through a grommet with the controls.
Yes you will need to scare up an after market switch.
It could be handy to have another switch on the rear.
While the 60 has a little age, if maintained, it should provide good service.
Available cash is always a concern.
Do you know what pitch the prop is on the 60? Typically a toon will have a much flatter prop (13 or less) than a runabout (15 or greater).
In lieu of checking the compression, turn the flywheel by hand a few times. It should feel consistent and require a little effort. Unfortunately, this sense only comes with experience. But, if one cylinder is significantly low on compression, you should notice it.
Let us know how it runs.

 

[Maddoxsdaddy]

Re: replacing a 40hp merc with a 60hp merc...

Ram the motor for about 10 minutes on the muffs. Cowling lookd its age but the motor itself looks only a couple of years old. I need to plug the hole in the head where the water pressure guage hooks up because i won't be using one... anyone know the thread count and size of bolt needed to plug the hole? THe 60 has a wiring harness with ALOT of wires in it set up for running multiple guages. I don't have any guages on my boat. Do i really need any? I was thinking maybe just a tach...?

 

[mthieme]

Re: replacing a 40hp merc with a 60hp merc...

I've got a 3-cylinder manual.
I can help you identify the wires.
It's possible you might need an adapter for the harness or if you have enough slack, hardwire everything.

I don't know for sure about the water tap. It's probably either fine thread or pipe thread - guessing. Laddies might know. Haven't seen him on this week...might have to pm him.

 

[Maddoxsdaddy]

Re: replacing a 40hp merc with a 60hp merc...

Noticed a wire not running to anything in the area of the hole... maybe the hole is for a temp sensor? Whay do you think about adding all of the other guages? If i dont need to add anything now, i'd rather not due to my "right now boat budget"... Once i get my stimulus check, i'll have plenty $$$... (NOT!) But seriously, i probably could do without all the guages...

 

[mthieme]

Re: replacing a 40hp merc with a 60hp merc...

I've never had any gauges on an OB.
But, I like gauges. On my SeaRay, I have the full array and after watching them for years, I can tell when something is starting to become amiss just by one of the gauges being a little off from normal.
Dash real estate is another issue.
If nothing else, options are always a good thing.

 

[Maddoxsdaddy]

Re: replacing a 40hp merc with a 60hp merc...

Yeah... dash space is an issue. All i've got is a small side console. I do think i should at least have a tach. Maybe the other stuff can come later. I'm a little sceptical about wiring the motor myself so i may let a dealer do it. Anything else, i'm fairly confident i can handle. It would be nice to have someone put the wires together then let me know what the leftovers are for...