70's Mercury 65hp What year?

[LakeShaker]

Hello,
First time posting and hopefully someone can help me out. What I got is a I wouyld say early 70's 650 65hp Mercury outboard 3 cyl. Has serial # 23403046 on transom bracket and also stamped on side of head. My problem is everytime I give someone that # they are telling me it saiys it is a 4cyl which it clearly is not. Is it a mistamp from factory? How can I find out for sure what I have? Also i just picked up another lower unit to have as a spare which was said to be off a 75 65hp so I was told 72-76 were the same. Well this one has a square shift rod where mine has a round slotted type rod. I was told by a merc dealer they are interchangable. This is my first boat and outboard so I'm learning as I go so bear with me. I honestly claim to know nothing about outboards except to be able to tell a 3 cyl from a 4 cyl. So anyone have any ideas or expierence with this situation? Thanks in advance.
Bill

 

[Plainsman]

Re: 70's Mercury 65hp What year?

Welcome to iboats Bill !!

Check out maxrules.com to find the year.
You seem to have an extra digit in your number

 

[LakeShaker]

Re: 70's Mercury 65hp What year?

Henry,
I have been there with no luck either, even talked with them on the phone and they said 1 too many #'s also but that is what is on this motor, On the tag on the transom bracket and also it is stamped into the block/head of motor on drivers side toward rear of motor on flat machined surface. 8 digits,,, everyone is guessing around 72/73 but noone can say for sure. They say if you drop the last digit it will make it a 4 cyl drop the 1st digit and it is within 3 cyl area. One guy at mastertech asked about color stripe around cowl, told him it was blue and then he said 72-76' so i don't no where to go because noone knows.

 

[Plainsman]

Re: 70's Mercury 65hp What year?

Someone may come along with a better answer for you.

 

[emckelvy]

Re: 70's Mercury 65hp What year?

I'm guessing you're correct and it's a mis-stamp. If you drop the first "2" you get a ser # which corresponds to 1972 model year, first year for the 650-3.

At any rate, if you have a blue stipe of solid color with the "Mercury" letters in the middle, that's the correct year range. And I expect it has a distributor too.

Don't believe the parts and tuning info changed much for the early 3's, until they went to ADI in '76, then to 70HP in '77.

Probably with exception of that square shift rod, I remember seeing some of those Pesky Buggers! I guess they'd probably be easier to get aligned than the splined ones but whatever!

And the dlr is correct, you can unscrew the shift shaft bushing, then remove the square shift rod and replace with a splined one. Beware that the shift clutch applies spring pressure against the shift cam via a spring-loaded plunger in the forward end of the propshaft. If you just pull the shift shaft out without taking precautions, spring pressure will push the cam to a position out-of-line with the shift shaft and you won't be able to insert the new one.

To set things up correctly, place the lower unit in Fwd gear. Turn the propshaft in a clockwise direction and you'll hear and feel clicking as the 'ramps' of the shift clutch 'walk' up the ramps of the fwd gear, then fall off with a sharp click. This is normal ratcheting action which you'll hear if you were to turn the engine off while at speed, underway in gear. This keeps the prop from dragging in the water so much that the motor will (quite dangerously) kick up then fall back down.

As you 'ratchet' the propshaft, just as you feel it's about to 'click', Stop! This is the perfect position for removing and reinserting the shift shaft, as it relieves the spring pressure on the shift cam. Be sure you have the lower unit set upright (with the propshaft to the horizontal, drivshaft vertical). That way the shift cam won't try and move out of position.

A few other things you'll want to do are the Clams Canino Link and Synch, instructions found on this forum. Set your maximum timing advance back from the recommended 23 deg BTDC on the timing sticker, to around 20-21. This'll keep your motor from detonating. Take a look at the current "fuel" thread and you'll probably want to be sure to use non-alcohol, mid-grade gas.

Put a new water pump kit in and renew the impeller every year. These motors are extremely hi-stressed and you need the cooling system to be at optimum.

Check out the threads regarding relocation of the telltale water outlet to the top of the block, this positively vents the block and ensures you get no "hot spots" in the cooling passages. This can lead to a cracked #1 cylinder. Seen lots of these motors lose an impeller and they overheat so hard that the block cracks - nonrepairable.

Prop to the max rpm at Wide Open Throttle (WOT) with one person and light load in the boat. This motor must not have such a large-pitched prop on it that it lugs down below rated rpm. It's only 49.8 C.I. and needs to rev up to make its rated power.

Anyway, hope that helps pin things down a bit for you, HTH & G'luck with the motor.......ed

 

[LakeShaker]

Re: 70's Mercury 65hp What year?

Hey Ed,
Thanks for all the info, actually I made a mistake in the first post as to what the dealer said, he said they WERE NOT interchangable! but you are sure they are? So they both have the same ends down next to the prop shaft? I'm just asking because I didn't know if they might have the same set-up as mine now, it has the splined shaft at the top of the long(intermediate) shift shaft coming from where it hooks to arm from cable and splined on sleeve where 2 shafts meet right out of top of lower unit and didn't know if it was splined the same way down in the unit, but wasn't sure if the one that was square would be the same square top,square middle , square bottom!!!

So what you are saying is they are both the same ends that are down in the lower unit right?
So I can take of the little plastic whatever piece that turns with the shaft that slides over the shaft in lower unit, then the little washer like piece with the 2 ears that lock it in and then the one under that with 2 slots (one on each side) will screw out? And once that is out the shaft should slide right out? Just make sure unit is vertical keeping porp shaft horizontal and the cam clutch right on the edge of clicking down and the other shaft should slide right back in?
LMK if I got that right? I don't know because that sounds too easy to do anything with this motor so far.
If this sounds right I may give it a shot tomorrow.
Bill

 

[emckelvy]

Re: 70's Mercury 65hp What year?

Bill, all the shift shafts have splines at the bottom, where they engage the shift cam.

Sounds like you've got the drill down pat, for removing/reinstalling the shaft.

There's a special tool for the shift bushing, but you can take a steel pipe or deep socket of appropriate diameter and grind 2 "tabs" in it to engage the slots in the shift bushing.

Note that you'll probably want to renew the bushing or at least the seal. The bushing comes with a new O-ring, and new seal already pressed in, so that does save you a bit of pain, although it's more $$ than purchasing the soft goods separately. You'll probably find that the dlr stocks the bushing assy but not the separate parts.

BTW, you'll greatly ease the removal/reinstallation of the shift shaft if you first drain out the gear oil. Otherwise you're going to have a hard time seeing the shift cam once you get the shaft out. Plus, all that undrained oil coming off the shift shaft when you withdraw it from the lower unit is Nasty!!

Now, if for some reason the shift cam moves, you can get it back by jostling the lower unit to and fro. This'll get the cam back to the right spot. Another reason to drain the oil out. If you find the cam is reluctant to move due to residual 'sticky' Hi-Vis gear oil, use compressed air to blow the oil away, or give it a quick spritz of WD, PB Blaster, whatever's handy.

Once you're done, refill with fresh Hi-Vis (get some at Wal-Mart for around $3/quart) and enjoy!

Let us know how it turns out..........ed

 

[LakeShaker]

Re: 70's Mercury 65hp What year?

Thanks for the reply Ed, haven't had a chance to try it yet but maybe today and will let you know how things work out. Oh and yes it does have a distributor.
Bill

 

[LakeShaker]

Re: 70's Mercury 65hp What year?

Hey Ed,
Got the shafts changed today, was actually a piece of cake as i did it just how you explained. Thank You!! Only thing you didn't mention was the lower unit the square shaft came out of actually had a flat spot on shaft where as the one with the splined shaft was splined all around. So I looked at them and they looked exactly the same except for square top and flat spot on botton, so I took one of the teeth of on my grinder and made it look exactly like the one that came out and it slid right in just as the original(I hope that doesn't hurt anything, I took it slow and made sure not to get the shaft hot so i wouldn't bother the temper if any) but we will see I guess. Got water pumping now and found a leaky exhaust gasket so that's next. Another thing is now my reverse on shifter is forward on motor and vica versa could I have gotten the bracket reversed on the top shaft or gotten the shaft in the lower unit 180 deg out when it went back together? (in another thread also) i'm done today until I get the gasket and I will go at it again. Thanks for all your help so far.
Bill

 

[emckelvy]

Re: 70's Mercury 65hp What year?

Bill, forgot about that flat spot! I expect they did that to ensure the square upper was in the correct position. I wouldn't think that it'd matter with a splined upper shaft. Of course, it does matter going into the shift cam end, and it sounds like you were quite handy in resolving that!

On your shifting issue, it is quite common to be off on the 'clocking' of the shift shaft.

Best way to locate things is to place the lower unit in Neutral. Place the remote control in Neutral also. If the upper shift shaft is slightly off when you reinstall the lower unit, you'll have to disconnect the shift cable from the motor and move the linkage a bit until it lines up. After reinstallation, readjust to get correct F-N-R shifting.

BTW, the shaft moves CCW to shift from Fwd to Neutral to Reverse.

So, if it's in Neutral, one click CW gives you Fwd. One click CCW from Neutral gives you Reverse.

If you messed with the linkage coming down from the top of the motor, make sure it's also shifting the same way. If not, that could be the source of your reversal. But it's more common to have the shift shaft "out of whack".

Don't forget to realign the reverse lockout cam onto the shift shaft. In Fwd gear the shift lockout rod should be hitting the ramp on the cam about halfway up. In Neutral and reverse the lockout rod would be at the top of the cam. If it's not set up right, just pull the cam up and move to the correct position.

HTH..........ed

 

[LakeShaker]

Re: 70's Mercury 65hp What year?

Sounds good Ed, I will give it a shot maybe tomorrow after I try and find exhaust gaskets. I'm sure I will have to order them or get them online somewhere. Any place online better than others or any you suggest? Also if water was getting to my cylinders due to gasket leaking would that be my problems as far as not idling or wanting to run? Would it have hurt anything by that happening? May be a simple question but I'm not sure that's why I ask.
Bill

 

[emckelvy]

Re: 70's Mercury 65hp What year?

Bill, if you pull the spark plugs after running and see drops of water on them, water is definitely getting inside the motor. If it's been run for a long time like this there could be problems. Not so much if just for a short time in fresh water. Salt water ingestion tends to do the innards "in" in a bit shorter time frame, though.

If you're just seeing external leakage I wouldn't worry as much about water inside unless you see evidence via drops or a "super clean" spark plug. Excessive fuel will wash a plug clean, and water ingestion will 'steam clean' all the carbon off a plug.

Providing the motor's got good compression, the idle thing could be simple as an idle mixture adjustment. Or "trash in the cap". Check the dist cap for debris, I've had quite a few motors with very dirty caps inside and it caused crossfire/missing/surging. You can use some carb cleaner to wash out the cap, followed by a good shot of compressed air.

If you're going to take the exhaust manifold cover off for gasket renewal, be careful of stuck bolts. If you break a stainless bolt you're guaranteed to need a Heli-Coil repair. Done enough of those on Salty Dogs that's fer sur!

Use heat from a propane or Mapp torch to help loosen any reluctant bolts. PB Blaster might also help after the bolt starts to move.

Clean off all gasket residue with a gasket scraper or chemical remover; don't use those Scotch-type abrasive discs. Check the inner baffle for perforations and replace if it's corroded badly.

Newer Merc gaskets have a special coating on them, if you get that type don't use gasket sealer. If they're older, uncoated items, use Permatex No. 3 Aviation brush-on dressing on gasket and bolts. Torque the 5/16-NC bolts to 200 in-lbs and any 1/4" bolts to 70 in-lbs.

I use www.boatfix.com for Sierra aftermarket parts. This site sells them also.

Look up parts for older Mercs at http://www.dougrussell.com/partscatalog/collections/index.cfm?fuseaction=collectdetails&colid=01 and you can punch in parts numbers at www.mercurypartsexpress.com for the latest dealer prices on OEM parts.

If you have a NAPA nearby, they may be able to order some parts thru their catalog. These have NAPA packaging but come from Sierra and have the familiar "18-####" part # format.

Anyway, keep on plugging, you've chosen quite the motor to begin your adventure in Outboard Mechanics 101, but if she's good inside you'll get 'er eventually !..........ed