1968 Mercury 20hp (11hrs old)

[baconbiscut]

here is the story behind this motor. I got it from my uncle today in the mail its 11 hrs old and hasn't been run In 15 years. si i get it put it on the stand and connect a fuel line mixed at 24 to 1 just to be safe since it had been sitting. I looked under the cowl and everything was new looking and it had original factory grease. The flywheel was still a shiny red and not a spec of dust the coils also looked great and original spark plugs. because the motor had The first three pulls it nothing. The fourth pull it caught and started up. it didn't pump at first. So i cut it off. the next try i did with choke off it fired up i gave it a little gass and it started pumping I then let it idle down it was still pumping alright. I felt the power head it was nice and cool it wasn't over heating. So i'm worried about the impeller should I replace it or could I use the engine through the summer and replace it in september or august. oh and by the way the engine ran great after its first start in 15 years i couldn't stop playing with the thing man I was excited!

Any ideas or thoughts are greatly appriciated.

Dan

 

[8075mercury]

Re: 1968 Mercury 20hp (11hrs old)

Wow, you are lucky to acquire a real gem!

I replace the impellers on these models 20's every couple of years and particularly if the motor has been sitting up for 6 to 8 months. I find the impellers take a set without use and putting in a new one is cheap insurance. The original driveshaft on these was carbon steel and so prone to rust so check your lower unit oil frequently. Great redstripe motors!

 

[baconbiscut]

Re: 1968 Mercury 20hp (11hrs old)

Wow, you are lucky to acquire a real gem!

I replace the impellers on these models 20's every couple of years and particularly if the motor has been sitting up for 6 to 8 months. I find the impellers take a set without use and putting in a new one is cheap insurance. The original driveshaft on these was carbon steel and so prone to rust so check your lower unit oil frequently. Great redstripe motors!

thanks do you know if this engine has a thermstat in it.

Dan

 

[8075mercury]

Re: 1968 Mercury 20hp (11hrs old)

No thermostat on my 68 20hp Mercury.

At a minimum, I would order a parts manual from Mercury Marine for $15 which is really helpful in getting and identifying parts. A factory service manual from ebay is also very useful.

Good luck with your classic!

 

[Harker]

Re: 1968 Mercury 20hp (11hrs old)

LUCKEEEE! Change that impeller now. There is a lot of info on www.oldmercs.com and you can probably find a parts diagram here onine http://www.marinepartsman.com/. Good luck with it and treat it right.

 

[baconbiscut]

Re: 1968 Mercury 20hp (11hrs old)

here is the story behind this motor. I got it from my uncle today in the mail its 11 hrs old and hasn't been run In 15 years. si i get it put it on the stand and connect a fuel line mixed at 24 to 1 just to be safe since it had been sitting. I looked under the cowl and everything was new looking and it had original factory grease. The flywheel was still a shiny red and not a spec of dust the coils also looked great and original spark plugs. because the motor had The first three pulls it nothing. The fourth pull it caught and started up. it didn't pump at first. So i cut it off. the next try i did with choke off it fired up i gave it a little gass and it started pumping I then let it idle down it was still pumping alright. I felt the power head it was nice and cool it wasn't over heating. So i'm worried about the impeller should I replace it or could I use the engine through the summer and replace it in september or august. oh and by the way the engine ran great after its first start in 15 years i couldn't stop playing with the thing man I was excited!

Any ideas or thoughts are greatly appriciated.

Dan

one more thing i wanted to add. when the engine is running it will **** out water fine but it won't sputter water out of the exhaust ports does the water start spitting out of those when you get the engine going on a boat becuase i couldn't advance the throttle past start. while it was running the engine remained Very Cool and di not overheat.

Thanks,Dan

 

[Motor Boater Bill]

Re: 1968 Mercury 20hp (11hrs old)

As long as the water is coming out the telltale it is pumping, but I agree with others here, replace that old impeller--it will pump better and will be reliable. That old one will be curved and hard, and won't pump as well at low speed as a new one, which may be why it's not coming out of the exhaust as well as the telltale. Put it in your spare parts box for an emergency if you want to. You only have to have one hard chunk break off of that old impeller and block the tube or get up into the water passages in the motor to cause real trouble. And nobody drives their boat while staring back at the telltale the whole time, do they?