1974 mercury 65hp newbie owner

[fishysmell]

Hi all.

I bought an old boat this past summer and have quickly learned that this also means I have become a mechanic this past summer. While I am somewhat mechanically inclined, this is a whole new arena to me. I am having several problems that I would like to work through, but I thought I would start with a "simple" question and work my way up from there. Here goes: I would like to find the model/serial number for my motor. It is a 1974 mercury 65 HP and the cowling has a blue band on it. Where do I look for this info on the motor? I have inspected and found nothing, so any help is greatly appreciated. Thanks ahead of time...all the posts I've read as I search through this site have already helped my knowledge bucket greatly.

 

[Yepblaze]

Re: 1974 mercury 65hp newbie owner

For the numbers, look between the two thumbscrews that hold the motor to the boat. It may require that you wipe away the grease to reveal an aluminum tag attached to the main section of the motor's swivel assy.

 

[fishysmell]

Re: 1974 mercury 65hp newbie owner

Thanks! I'll check that when I get home tonight.

 

[jcsercsa]

Re: 1974 mercury 65hp newbie owner

Hay , here's a link to a great site,http://www.oldmercs.com/197476Merc650.htm Hope this helps !!!! John

 

[fishysmell]

Re: 1974 mercury 65hp newbie owner

Thank you so much Yepblaze. I can't beleive I missed that plate...I was looking all over the block for it. Duh!

Jcsercsa, thanks for the link. My next question was going to be, "Does anyone have a good source for parts for this motor?"

This forum rules. I'm sure I'll be posting again since I am going to remove my lower unit to repair the reverse lock mechanism. Until then, thanks a million

 

[fishysmell]

Re: 1974 mercury 65hp newbie owner

Here's one of my current problems. Last time I was on the water, I was putting along in the no wake zone. Boat is running swell (as long as I stay out of reverse, which is another problem) until I throttle up and i can't get on a plane. I think I have a spun prop, as this has already happened once. The first time I paid $300 for the fix. My prop is old and beat up and I don't have a spare so either way I'm going to buy a new prop, and have this one re-hubbed (if it fixes the issue) as a back-up. The rear thrust washer is totally chewed up, and the front one is cracked. Is this normal with wear? Will these come with the new prop or do I need to find them separate? I assume I should just get a prop with the same pitch (11") but any thought on that? I'm not sure I have a spun prop, but this seems like something I need to fix anyway. Does anyone want to point out something obvious I'm not thinking about or noticing? I'm really new to this, but I want to get back out on the water. The weather has been so great lately!

 

[Chris1956]

Re: 1974 mercury 65hp newbie owner

Fishy, If you have a sspun prop, the motor will rev up, but the boat speed will not usually get above a fast idle. Running a beat up prop is not a good idea for performance or safety.

You can order a replacement prop from Iboats or many other outlets both web based and local stores. The only way to know wnat prop is best is to try one and see what the max RPM is. If the MAX RPM is too low (<5200 RPM) the prop needs less pitch. if the Max RPM is too high (>5800RPM) the prop needs more pitch.

BTW - a rehub job should cost <$100. A prop recondition is significantly more. You can get a new aluminum prop for that motor for about $125-$150, less if you find a sale.

 

[Chris1956]

Re: 1974 mercury 65hp newbie owner

Fishy, The thrust washers should not crack. Replace the rear thrust washer. The new prop should come with a new front thrust washer (and plastic replaceable hub as well), and maybe a new rear thrust washer.

 

[fishysmell]

Re: 1974 mercury 65hp newbie owner

Thanks Chris. One question about RPM...I don't have a tachometer. Is there another way to find my max RPM once I have the new prop on?

 

[Chris1956]

Re: 1974 mercury 65hp newbie owner

There is no way to accurately determine RPM without a tachometer. The best you can do is to use a prop calculator and a GPS to estimate the RPM. You fill in the prop pitch, gear ratio, MPH and guess at the boat's prop slip, and it will return the RPM