1978 Mercury 125hp motor.

[Nutron]

Just had a question about this motor. I have a friend of mine that wants to sell this motor to me. I need a motor for my boat and was interested. I know nothing about these motors so I need a few questions answered if anyone could.
1. Is this a good motor?
2. Are they reliable, is the motor to old and would break down sooner than later?

He is selling it for 500 bucks and it does run well, I would tell you it is extremely fast! I have a 135 evinrude and this motor just makes mine look like its standing still.

Thanks for anyone that can help me out with this, I would like to know if I'm getting a good deal or not.

 

[Faztbullet]

Re: 1978 Mercury 125hp motor.

They did not make a 125 in 1978...if its a inline 6 cylinder its a 1968 or 69. If its the late model 4 cylinder that a heck of a deal!!!

 

[Nutron]

Re: 1978 Mercury 125hp motor.

Ok, he just told me he doesn't know the year. All I can say is it's a 6 cylinder 125 thunderbolt. I will get more info.

 

[Mi duckdown]

Re: 1978 Mercury 125hp motor.

Get serial Number from motor.

 

[Nutron]

Re: 1978 Mercury 125hp motor.

Will do, I will post it tomorrow.

 

[Nutron]

Re: 1978 Mercury 125hp motor.

Here's what I have, the serial number 2400094P the front hood says Mercury 1250, 125 hp Thunder bolt ignition. I couldn't find the Model number does this help?

 

[79Merc80]

Re: 1978 Mercury 125hp motor.

Here are the results.


125 1968 2314956 - 2536209 Canada 2317876

125 1969 2536210 - UP Canada 2539470

 

[Nutron]

Re: 1978 Mercury 125hp motor.

Do you believe 500 bucks is still a good deal? Just want to make sure.

 

[Chris1956]

Re: 1978 Mercury 125hp motor.

Seems a bit high to me.....JMHO

 

[Faztbullet]

Re: 1978 Mercury 125hp motor.

Do you believe 500 bucks is still a good deal?

Naaa as you can get a later model motor with more HP if you look. Below is a 1987 150Hp for $750
http://nashville.craigslist.org/boa/3245490601.html

 

[mr 88]

Re: 1978 Mercury 125hp motor.

IF you can't find one in your area as suggested you may want to few things. Compression test would be step one then on to the impeller. Is it a short shaft motor? does it have a power trim set up ? has it been torn down,wire with lead seal would still be hanging in the front corner of the block if not,condition of wiring/ harness.Lower unit has decent lube and no water intrusion is something else and while your down there see if the prop will come off,sometimes the "weld" themselves to the shaft if never removed.All engines will break sooner or later,but if all the criteria is met with the tower I would expect a minimum of breakdowns.It is a "northern" motor so hours may be okay on it ,I am sure it sat at sometime for a few years, if not more. Not knowing how it was serviced things that may want to be touched on,clean-take apart starter to clean up contact points.If you start it up and hear a squealing sound for a instance that may be the one of two sealed bearings in the distributor.Fuel pump/carbs/lines may also need attention. Is it a crapshoot,maybe but buying a 1500-and up along with the electronics on a newer engine may have fewer problems pop up, but when they do it's a major bill $$$

 

[Nutron]

Re: 1978 Mercury 125hp motor.

Well I got the motor home and started with the basics, the motor hasnt ran in about a year and a half. I sparyed some sea foam and put a little oil in each cylinder, I let that sit for a while, then I checked all wiring out. Some of the wiring is corroded the coating is pealing off. I am going to replace that doesnt look like a big deal just time consuming. Some of the fuel lines are dry rotted so I am going to replace those, they don't leak but are cracked a little. let the mixture sit in the cylinder for about an hour, then I hooked my battery up and cranked the motor over without trying to start a few times to let the cylinder walls try and coat a little. I also opened up the carb bowls a let some of the old fuel out, not much to speak off. I hooked up a new fuel line and bulb and cranked the motor over and it fired right up sprayed a little sea foam down the carb throats and some carb cleaner. The motor took right off, idled fine, went into gear without reving up I just wanted to hear it the motor is great absolutely crazy how this old motor just fired right up. let sit yesterday went back out in the morning did a compression check and every cylinder is 130 to 135 is that good? also on a few places on the block motor it is stamped "Factory remanufactured power head" did someone put a new power head or do they all say that. My buddy I bought the motor off of never used it and he bought it off a guy who said he used it a few times but hardly at all. besides the lines and fuel hoses the motor is sparkling clean no major oil or grease all over it's like it was never used. Who knows. Thanks for all the help, Oh the only question! the power trim and tilt I hooked it up, it has power but when you try and use all there is is a clicking sound? would that be the solenoid that went bad?

 

[mr 88]

Re: 1978 Mercury 125hp motor.

Compression is good..New power head was put on it,no big deal.Change water impeller,it may be dry rotted.Try taking a 12 volt jumper lead and by-pass solenoid ,that will confirm pump is good and/or solenoid is bad.

 

[Nutron]

Re: 1978 Mercury 125hp motor.

Not to sound like an idiot but how is that done? the Jumper.

 

[wired247]

Re: 1978 Mercury 125hp motor.

Don't get too happy with your purchase until it get in the water and runs. Running on the muffs and running in the water are two different things.

 

[Nutron]

Re: 1978 Mercury 125hp motor.

Believe me I know that all to well.

 

[Nutron]

Re: 1978 Mercury 125hp motor.

And I didn't pay the 500 stated earlier, I paid 150 bucks.