1970 650 65hp Merc. Lower unit compatibility diassembly

[mikmic2]

Hello,<br />I have a 1970 65hp mercury. Ser# 2873792<br /><br />At least when I looked it up online I came up with a 1970. Is this correct? <br /><br />Does anybody know what lower units will work for this engine? This is a long shaft.<br /><br />Are these engines pretty hardy?<br /><br />Just wondering if they seem to hold up good, before I search for a lower unit. It does have good even compression.<br /><br />Thanks in advance.<br /><br />T

 

[rickdb1boat]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

Hi BillyBob<br /><br /> Sorry, I don't know what years will work on the lower unit, but those are very good motors if taken care of. Yours is indeed a 1970 Model. I had a 67' 650 that I still wish I had. Ran great every time and no real problems at all. Here a little more info and a parts source for your motor. Others on here are more familiar with the interchangability of parts and should chime in soon....<br /><br /> www.oldmercs.com

 

[roger3645]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

I think most of the LU on your inline 4's from that same erra will interchange, 50hp - 85hp.

 

[mikmic2]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

Hey Rick, thanks for the info, and reply. <br /><br /><br />Roger,<br />When you say that era, what do you mean?<br /><br />From 1965 to 1984 or so?

 

[roger3645]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

Yes, some of the models have a spring plunger on top of the drive shaft while the later models don't. I think inline 4's have the same gear ratio so replace a model with the plunger with a model with the plunger. I believe yours has the plunger. I have a 1975 85hp that also has the plunger.

 

[mikmic2]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

Hello,<br /> Mine doesn't have that little spring loaded thing at the tip of the driveshaft that you are talking about. Mine has a hole in there, but not a spring loaded pin. <br /><br />Is that what your talking about being the plunger?

 

[roger3645]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

Yes the spring loaded pin is what I was refering to as the plunger. I believe it is used to keep a bit of downward pressure on the drive shaft. What's wrong with your lower unit?

 

[mikmic2]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

Hello,<br />It was full of water and froze up and busted. <br /><br />So, Now it's rusted and busted. For the price of a gearcase and anything else I might need, it is just better to get a different one.

 

[roger3645]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

I believe there's one listed on ebay.

 

[mikmic2]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

I've been watching there, but it is to hard to tell which ones fit. That's why I was asking here. <br /><br />Then, when I find one that I am pretty sure will work, the people won't get back to you, when you ask questions, such as...<br /><br />What did the lower unit lube look like?<br /><br />Does it spin freely?<br /><br />Do you know if it leaks?<br /><br />Will it shift back and forth from reverse to forward as you are turning the driveshaft?<br /><br />I won't bid unless I get an attempt at answering those questions. <br /><br />I want a unit that has a chance at life. <br /><br />I already have a dead one, I don't need another dead one that can't be resurrected. LOL<br /><br />I have heard that the 3 cylinder and 4 cylinder lower unit's are different. Does that mean you can't convert them?<br /><br />So, it looks like the 50 to 85 hp will work.<br /><br />Where can a guy find out which years will fit mine?

 

[Chinewalker]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

NO! The 50 hp lower units will not fit! Neither will the 85hp units. The 65 hp had a unique unit. The 85 used basically the 6-cylinder unit (think it had a different ratio, though), while the 50hp used the same as the 35hp unit. It wasn't until the 65 lost a cylinder and became a 3-banger in '73 that it used the basic 50hp unit , albeit with a different ratio. You need a unit off a 4-cylinder 65 - no way around it. I'm pretty sure the units from '69-'72 will fit....<br />- Scott

 

[mikmic2]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

Thanks Chinewalker.<br /><br />I think I have put the last pieces of the puzzle together. <br /><br />If I look at this link.<br /> http://www.maxrules.com/merc_contents.html <br /><br />And look up my serial number 2873792 I come up with a 1970. <br /><br />It appears though, they only made the 65 hp until 1971, because after 1971 all they list is the 3 cylinder. <br /><br />For 65hp 4 cylinders from 1968 to 1971 they have the same micro Card listed. But the same parts list only goes from 1970 to 1971.<br /><br />So I am guessing that I would be sure to get the same lower unit if I stayed with a 4 cylinder either a 1970 or 1971. <br /><br />I just wonder why they share the same micro card 1968 to 1971, but the parts list is different for the 1968 to 1969, vs the 1970 to 1971.<br /><br />So evidently there are some different parts for the 68 and 69 that the 70 and 71's don't have. <br /><br />Whether or not the parts difference affects the lower unit or not, I don't know.<br /><br />But at least I have two models that I know will work. LOL <br /><br />I have a shot at a lower unit that comes from a engine with a serial number of 2805287. My serial number is 2873792. According to the above link, these are both 1970 65hp engines, and should share the same lower unit. Am I correct?<br /><br />Thanks for all the replies, and if you have additional information that may help, regarding the parts lists and micro card thing, it would be appreciated.<br /><br />Thanks for Chiming in, Chinewalker. (Pun Intended)<br /><br />LOL

 

[mikmic2]

Re: 1970 650 65hp Merc. Lower unit compatibility diassembly

Anybody know if I can use any other lower unit besides the 1970-1971 4 cylinder 65 hp lower unit?<br /><br />Is there a chance the 1968 thru 1969 would work?<br /><br />Possibly even going back to 1965, as the 4 cylinder service manuals are the same from 1965 to 1971. <br /><br />Anybody?