1970 650 mercury 65hp 4cyl. rebuild

[road.ripper]

hi all . im kinda new to bigger boats so here i go .... i've looked at most posts here for my answers but now im confused lol . we have a 1970 650 merc ser #2807058 on a 15 ft north craft early 70's i believe , the boat was purchased with lower end damge on the motor ( skeg and prop ) and a sheared flywheel key . i have yet to look at the flywheel but i can move it around by hand. the skeg is missing about 2-3 " aswell . the prop is my issue it is # 48-65748-A1-17 and it is toast ! missing about 2" of ea. blade . not sure if the hub has spun but i figure i need a new one rather than trying to get it repaired due to what ever the impact was from . Assuming in can get this motor running im not looking for a fast prop but i dont want a tug boat either. i run on lake Ontario" west end mostly for fishing . some one has spray painted the hull black over old repairs so i have alot of work before we get her wet but thats another post ..

any hints what to inspect first how to go about it etc..
thanks all .
road.ripper
love the site by the way

 

[Bondo]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

Assuming in can get this motor running im not looking for a fast prop but i dont want a tug boat either.

Ayuh,... Assuming you get it running,..
I'd Assume the busted prop was about Right, so I'd start with another copy of the same prop...

 

[steelespike]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

I agree start with the same prop.See if a prop shop can rebuild though if you can find a replacement prop it may be more cost effective.
You will need to test for your max rpm and speed The 650 is rated at 4,800 to 5,300 rpm You will need to prop close or at 5,300.So you may need to
fine tune your prop size.Let us know when you get things going.

 

[road.ripper]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

thanks for the advice , first thing i need will be a manual . i will post more as i get into the motor

 

[road.ripper]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

first i will be taking a lot of photos before i begin tear down here is a new question ...
how do i check for a bent prop shaft any teltale signs i should look for ? other than the obvious , im planning on pulling the plugs and turning it over manually to look for deflection if that dont work out then i will pull off the flywheel tonight and have a looky at the keyway , i will have to make another key
road.

 

[road.ripper]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

well the prop shaft does not look bent to my naked eye .. ok onto the engine, after taking lots of pics , removed the cowl cover then removing the case surrounding the flywheel , found the electric choke wire was toasted .. needs to be replaced ... then i found the timing belt broken .... timing must be reset on rebuild . now, since i was told it was running when it stuck whatever by the prop... would this be normal to bust the timing belt from a prop impact ? As a home mechanic i wouldnt think so .. there does not seem to be any busted rods or internals since it turns over by the rope from the flywheel ( 5 cycles ). although i know the flywheel key is sheared , i guess i have to buy a new socket to fit the flywheel nut, a piece of key stock , a gear puller , fabricate a flywheel gear holder , and a custom made plug socket for the bottom sparkplug ... ( a trip to princessauto ...woohoo new tools !!!!) and the pistons look good from plug holes (used a micro flashlight). hopes up meter is at 10

 

[steelespike]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

You should do a compression check.Should be able to hand crank with plugs out if necessary.100 psi is the minimum suggested.

 

[road.ripper]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

yes steelespike , i was thinking today about other things to check ...a comp. check would be a good idea . thanks . this is a winter project , in Canada thats about 6 months of cold fishing lol ... we went out today near a local dam for walleye ... brrrrrrr no fish but good conversation .

 

[ASHCAN]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

nice to see somebody rebuilding the same motor, in the midst of tearing down 75' 650, yours sounds like my twin massive chunk missing from skeg and a swiss cheese prop. the more I tear down the more its lookin like an anchor. good luck with yours!

 

[road.ripper]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

wow ASHCAN, i was begining to think im in all by myself with this one . but my hopes are still up , mine dont look as bad as i thought it was going to be . my prop must have taken the brunt of the impact and twisted the hub sleeve around. other than my prop and skeg ... so far all i have really found was the timing belt broke and the flywheel key sheared . i will post more as i go . keep in touch with yours too . i will do a compression test next and post my numbers . is yours a 3 cyl or a 4 cyl ?

 

[Fun Times]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

hi all . im kinda new to bigger boats so here i go .... i've looked at most posts here for my answers but now im confused lol . we have a 1970 650 merc ser #2807058 on a 15 ft north craft early 70's i believe , the boat was purchased with lower end damge on the motor ( skeg and prop ) and a sheared flywheel key . i have yet to look at the flywheel but i can move it around by hand. the skeg is missing about 2-3 " aswell . the prop is my issue it is # 48-65748-A1-17 and it is toast ! missing about 2" of ea. blade . not sure if the hub has spun but i figure i need a new one rather than trying to get it repaired due to what ever the impact was from . Assuming in can get this motor running im not looking for a fast prop but i dont want a tug boat either. i run on lake Ontario" west end mostly for fishing . some one has spray painted the hull black over old repairs so i have alot of work before we get her wet but thats another post ..

any hints what to inspect first how to go about it etc..
thanks all .
road.ripper
love the site by the way

Here is some updated info from mercruiser about your prop with the part number you posted, You could still orde it from any Mercruiser Dealer, Or you could more then likely find it online someplace like for exampl here at iboats i'm sure has it.

65748A1 is Superseded to 77344A45
Class:48
Supersession
Item Number: 77344A45
Status: Active
Weight: 7.563 lbs
Description: BLMX 13 1/4R17
Package Quantity: 1
MSRP: $165.39 Price
003 - FOND DU LAC,WI Has Over 10 in stock.
073 - ATLANTA,GA Has Over 10 in stock.
075 - FRESNO,CA Has Over 10 in stock.

 

[road.ripper]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

well tried to do a compression test .. i realized that wont work till i get the flywheel key replaced haa haaa ... so its off to get a harmonic puller .
todays $64,000 question .... a rod drop test, how much play is acceptable on the piston ?.. if i try it at tdc they are rock solid with no play BUT with the piston about 1"-2" lower then tdc i can wiggle the piston in the cylinder and hear lots of knocking and i fear rod bearings are shot, i cant see any end play on the crank . is there and easier way to check the rod bearings without opening the block ? Just for emotional support how much would it cost me in parts and supplies to do a bearing job ? i can do the labour learning as i go... think ill go price up a rebuild kit ....

dont need another anchor i got a good one...

 

[road.ripper]

Re: 1970 650 merc rebuild ?

Re: 1970 650 merc rebuild ?

this post needs some exp. for an answer .


ok seems like my first intuition of a sheared flywheel key was wrong ...
i used a 1/2 drive socket and a home made flywheel holder to unscrew the main nut .. not much torque needed to unscrew it , i noticed, hmmm ? as i pulled off the flywheel wich came off by hand no puller required hmmm ? ? ? the complete flywheel came off easily ... but the key was intact .. hmm ? ?
strange huh ... as i picked it up from the center hole to inspect it i felt something odd ... with a closer inspection and dissassembly of the hub assembly i found the flywheel has sheared itself around the outside of the main bolts of the center hub ... it must have held together ONLY by the upper and lower bolt flanges !! So i have a new issue i now need a flywheel , i doubt it can be welded because the tear in the metal has no direct shape and i cannot tell the original placement for timing ?
has this happened to others ? wow ! that could have injured or decapitated someone...

So my query is : how hard is it to find a flywheel for this or what one will fit from other models ? the stamped numbers on the ring gear are G 7 43 32036 and the number on the other side 33849 ( im in hamilton ont. Canada EH!!)

 

[QC]

Re: 1970 650 merc rebuild ?

Re: 1970 650 merc rebuild ?

Hey road.ripper. I moved this over to the Merc - I/O section as you'll get more focused help here. This has definitely migrated from a prop issue . . . Good luck!!

 

[road.ripper]

Re: 1970 650 merc rebuild

Re: 1970 650 merc rebuild

thanks QC i was thinking about how to get the post moved to a better suited forum as i was updating the post today awsome site helpfull and insightfull
all smiles here ...

 

[Don S]

Re: 1970 650 merc rebuild

Re: 1970 650 merc rebuild

Not sure why QC would think the IO section would be the best place to put an outboard question, so why don't I just keep moving it to the Mercury OUTBOARD forum.

 

[QC]

Re: 1970 650 merc rebuild

Re: 1970 650 merc rebuild

Oops . . . I read Mercruiser somewhere . . . :redface:

 

[Bondo]

Re: 1970 650 merc rebuild

Re: 1970 650 merc rebuild

Oops . . . I read Mercruiser somewhere . . . :redface:

Ayuh,... I've been lookin' for 1 of those 650 Mercruiser motors,.....

 

[road.ripper]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

what a way to wake up and read the humour thanks again guys

 

[road.ripper]

Re: 1970 650 merc prop 48-65748a1-17

Re: 1970 650 merc prop 48-65748a1-17

ok to where ever my post may land next lol ..

looks like im searching for a flywheel for my 1970 650 4cyl merc . stamped numbers are as follows G 7 43 32036 and on the opposing side 33849 . any help ?