Buying mercury 650 - good bad or ugly??

[ShoestringMariner]

hey guys tomorrow I am picking up a boat and motor. Mostly interested in the hull (starcraft super sport) but wondering about the motor. I know NOTHING. About mercs. My understanding is that this is an old motor. Maybe early/mid 70s(?)

typically, are the good motors or stones? Is there anything besides the usual OB motor checks to look out for? I don't want to get stuck with a dog

tjanks in advance

 

[211libwtfo]

They’re great.....for anchors mho!!!

 

[flyingscott]

Does it run? Pretty good bet the wiring will bad or getting there.

 

[GA_Boater]

They’re great.....for anchors mho!!!

Oh yeah! The guy is looking for help, not humble opinion.

Merc 650 is a good motor as long as it was maintained. It is almost the same as the Merc 500 on my tinny and she has been purring for 52 years, well as long as I've had it anyway.

You do the same things as buying any other outboard. See if it runs and check compression. Do a lake test run if you can.

 

[racerone]

A 650 could be a 3 cylinder or a 4 cylinder.----I would stay away from the 3 cylinder which was 72 to 76 models.

 

[jimmbo]

Like racer, I too have reservations regarding the 72 - 76 3 cylinder models. They have an oddball fuel system design, 2 carbs feeding 3 cylinders. That said, there are people out there using and loving them. In addition to a compression test, inquire when the pump impeller was changed, and check to see if it has Watercooled gears.

 

[211libwtfo]

Oh yeah! The guy is looking for help, not humble opinion.

Merc 650 is a good motor as long as it was maintained. It is almost the same as the Merc 500 on my tinny and she has been purring for 52 years, well as long as I've had it anyway.

You do the same things as buying any other outboard. See if it runs and check compression. Do a lake test run if you can.

The OP was “wondering” and if all anyone did was spew fact on this site it would be very boring. ANY motor well taken care of will run great; But of the many motors I’ve had those Mercs don’t hold up regardless. I run on the Mississippi River and in back waters are very stumpy and and I had a 1957 30 hp rude for 4 years in high school regular maintenance never let me down. I’ve been let down stranded and empty pockets off of those mercs to many times. And that’s my honest opinion.

 

[ShoestringMariner]

Thanks guys, I think it’s around 75. Same year as the boat. Think it’s the original.
Checking it over tomorrow. Says it was “marina maintained”

 

[ShoestringMariner]

Like racer, I too have reservations regarding the 72 - 76 3 cylinder models. They have an oddball fuel system design, 2 carbs feeding 3 cylinders. That said, there are people out there using and loving them. In addition to a compression test, inquire when the pump impeller was changed, and check to see if it has Watercooled gears.

.Thanks, how do I know if it has water cooled gears? Also too, how hard is it to change impellers on these? I think I'd rather change the impeller anyway for insurance sakes.

And I did bring this home. I'd rather not re-power this boat if I don't have to

Oh, and don't laugh, but how to I release the tilt lock on this without pulling the pin right out? I cant find a release lever

It is a 3 cylinder. Seems to start and run good. restarts immediately with the touch of a key. 130 psi across the board

 

[GA_Boater]

If your talking about the reverse lock, shift into forward and the motor can be lifted. If you mean the tilt lock, there should be a lever on the starboard side, between the clamp bracket and swivel bracket.

I not sure what "water cooled gears" meant, either.

Impellers are not hard to do. The worst part is getting the water tube, drive shaft and shift shaft lined up during re-installation.

Facts can be boring and are backed up, whereas everyone has an opinion. This is a fact - I have no experience with the 3 cylinder models, so I won't comment about how good or bad the motor might be. It still comes down to how well it has been maintained over the years.

 

[jimmbo]

‘Water cooled gears’ meant water in the gear case.

 

[ShoestringMariner]

So first run with this motor today. Read grade on earmuffs. Was a little hard to start in the water for some reason. Got it running and it ran fine idling, low-speed at high-speed. Lots of power but 2 big issues;

1) it does not like to steer under full power. It’s almost like there’s no steering whatsoever. Is that normal? This is a much bigger motor than what I’m used to. My previous boat was only 18 horse.

2) Bigger concern; it goes bang bang bang in reverse gear. Sounds like it’s skipping in and out of gear Or like the gears are missing teeth. It was pouring rain by the time I put it in the driveway. Did not have Time to check and see if there is any water in the gearcase. The oil was fresh and new when I bought it. Any thoughts on why reverse gear would be like this? I would’ve thought that forward gears would wear out first.

 

[Tassie 1]

Can't help with the cause of your gearcase problem but think about looking for a 2nd hand leg to replace yours,
remember it's over 40 yrs old,

you should be able to find plenty of them over there,
we took one to the tip ( recycle centre ) here in Australia a few months ago after no-one wanted to buy it,

 

[KA9MOT]

What is the Serial number on your 650? You can use it to determine year. Don't take this as gospel, but I think all of the 40 HP and up 3 cylinder Lower Units are the same.

 

[racerone]

No----The 70 hp has a different gear ratio.-----It may just need cable adjustment to get reverse.----Or it could be bigger problems.----Can't tell without looking at it up close from here.

 

[ShoestringMariner]

What is the Serial number on your 650? You can use it to determine year. Don't take this as gospel, but I think all of the 40 HP and up 3 cylinder Lower Units are the same.

Thanks.
04261307. It’s a ‘76. Good to know that there some interchangeability.

 

[ShoestringMariner]

No----The 70 hp has a different gear ratio.-----It may just need cable adjustment to get reverse.----Or it could be bigger problems.----Can't tell without looking at it up close from here.

I wondered about that, but I do hear a bit of a a clunk of it going into reverse. Idle reverse sounds fine, It’s when I start to give it some acceleration that it goes bang bang bang. Could this still be an adjustment issue ?

 

[racerone]

I can not adjust it for you.----Up to you to do the inspection and work.-----And are you shifting quickly or easing it into reverse.-------It has to shifted with a quick firm motion.--------No " granny shifting " is to be done on that motor !

 

[ajgraz]

Did you change the impeller? Last person to do it maybe didn’t get the gear shift cam/ramp piece put back on right, so you can only “kinda” go into reverse.

edit: or the cam is worn out and needs replacing. Cheap plastic, not expensive.

 

[ShoestringMariner]

I can not adjust it for you.----Up to you to do the inspection and work.-----And are you shifting quickly or easing it into reverse.-------It has to shifted with a quick firm motion.--------No " granny shifting " is to be done on that motor !

The plot thickens! Because this is an old boat and motor, I am treating a very delicately. I did not shift hard because I was afraid the gears would mash. I am going to try that very thing. Hope that’s all it is