[jakestevens]

I have a few things going on with this mercury 65hp 3cyl, but one thing I noticed today could be the cause of most of my problems. While I could only get it to run with the fast idle lever engaged halfway, I walked around the outboard inspecting things. I noticed water blowing from the exhaust plate(I believe that's what it is called). I marked the area in the pic attached. My questions are: (1)Does the powerhead have to come off to replace this gasket? (2)If not, where would you start the tear down?
(3)What gasket kit will I have to order perform the repair?

Thanks a lot for all the info thus far!! I consider this forum a very important tool in my repairs.

[mthieme]

Yup, unless I'm mistake the studs/bolts right under that are for the power head.
Fortunately you can get just the powerhead base gasket (housing) gasket.
Available right here at the iBoats superstore!!!
A better man that me is going to have get you the part number though.
They run less than $10.

[emckelvy]

The gap indicated is the juncture between the powerhead and the exhaust adapter. You'll have to pull the powerhead to replace the gasket.

Check out the below site, pull up diagrams for your motor by Ser # and you'll see a parts breakdown for the gasket you need to order.

Check the parts category "shift linkage and exhaust plate".

http://www.mercruiserparts.com/Selec...asp?class_id=2

Your motor doesn't look too salty so it should be an easy teardown.

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

[jakestevens]

Thanks emckelvy for the link. My outboard is a 1975 650 3cyl. and the serial number range is 3547987 THRU 4382056. I saw the pic of the gasket on the "shift linkage and exhaust plate" diagram. It looks like the gasket is no longer available. Would there be another source for this part?

[jakestevens]

I had found a better picture of the diagram and I was reading the wrong number. So looks like it is available so thats great. I have lots of fuel leaking around the carbs so I was going to rebuild those as well. Is there any other associated gaskets I will need to replace or should replace while I'm pulling the powerhead?

[mthieme]

Sierra and Mallory have the whole powerhead gasket kits available (worst case). PN 18-4352 and 9-64208 respectively. The whole kit runs about $50.
These are easy to find....iBoats has 'em.

[jakestevens]

thanks folks.. I think I'll jump into it since I know I can get the parts, then order what i need.. I'll let you know what happens.

[mthieme]

Tip - check the lower motor mounts by rocking the motor back and forth. Watch for play at the lower mounts while doing this. If you have any play, this would be the time to replace them. Considering the age of your motor and you're popping the powerhead anyway (required to replace lower mounts).....food for thought...
Also, you may have to order through a Merc dealer if needed.

[noahnsteph]

If you're going to pull the carbs you might as well rebuid them. I have a 1973 Mercury 650 3 cyl and I found the complete rebuild kits for the carbs right here on iboats for $15.99 for each carb. The kits have every gasket, O-ring, spring and jets you will need to completely rebuild the carbs. I was very impressed when they arrived. Compared to what I'm finding for supposed carb kits for my mototcycle the kits for the 650 are a smoking deal.

[mthieme]

It's hard to disagree, but the last 65 was made in 1976. It probably wouldn't be hard to find work on that puppy.