Important if you own a three cyl 65 HP Merc!! We used this model on our hydroplanes and EVERY one we found in the outboard used or motor junkyard had a hole burned through the top cylinder head. We were able to buy them cheap for this reason and a good heli-arc job got them running again. After many of these burned through heads we discovered the reason it was happening. The water pump fills the area around the cyls. from the bottom, a design error allows a small amount of trapped air to remain at the very top of the top cylinder causing a very hot spot that can overheat the aluminum and weaken it to a point that a hole will blow through the top of the top cylinder. This engine has 'blind cylinders' which means what looks like a head, is just a water jacket cover. A simple fix to prevent this engine killing problem is to drill a small hole just through either the head cover or the engine block at the very top of the engine to evacuate this air pocket. Be careful to drill only though the water jacket and not all the way through into the combustion area. Put the smallest hose barb available from a hobby shop in the hole and run a tiny hose down towards the lower unit and you will never have this engine killing problem.
I have a 1974 65hp, I need to get it to where it starts up fast like this one, and also is the gear selector suppose to move easy when moving it by hand, I can not move mine by hand only with the control.
Mike Palmer make sure the carbs are done right and its synchronized correctly, good plugs and wires and of course even compression and hope your reed valves are good. as for lower unit check your linkage with the lower unit off to eliminate that it is not the problem before you rebuild the housing.
Can anyone tell me what that grey fabric type ground? is and exactly what its for. I have same motor and mine is just hanging there..I am assuming its for the starter as the starter was all messed up and I replaced it and was missing bolts. but was not connected before i fixed so just left it.Motor runs great. just curious as hell.
I believe you are talking about the ground wire that screws to the shroud bracket . its there to ground it because it is mounted on rubber for vibrations.
I have a 1975 too but i just have coils no distributor, my tell tale comes from the top of the motor too. Why the hose from the mid section to the fuel pump?
Actually, I believe in 1977 the 65 hp was dropped and replaced by the 70 hp model. I personally own a 1976 65hp, a 1977 85hp and a 1976 9.8hp. I'm currently collecting, I hope in time, the full lineup for these bicentennial Mercs. ;)
To clean them properly they must come off.record the jet settings before they are dismantled. Soak them in a good carb cleaner for overnight. Check that the floats actually float and rebuild. I strongly recommend using a service manual and Mercury parts.
Important if you own a three cyl 65 HP Merc!! We used this model on our hydroplanes and EVERY one we found in the outboard used or motor junkyard had a hole burned through the top cylinder head. We were able to buy them cheap for this reason and a good heli-arc job got them running again. After many of these burned through heads we discovered the reason it was happening. The water pump fills the area around the cyls. from the bottom, a design error allows a small amount of trapped air to remain at the very top of the top cylinder causing a very hot spot that can overheat the aluminum and weaken it to a point that a hole will blow through the top of the top cylinder. This engine has 'blind cylinders' which means what looks like a head, is just a water jacket cover.
A simple fix to prevent this engine killing problem is to drill a small hole just through either the head cover or the engine block at the very top of the engine to evacuate this air pocket. Be careful to drill only though the water jacket and not all the way through into the combustion area. Put the smallest hose barb available from a hobby shop in the hole and run a tiny hose down towards the lower unit and you will never have this engine killing problem.
Thanks again
Thank you!!!!!
I have a 1974 65hp, I need to get it to where it starts up fast like this one, and also is the gear selector suppose to move easy when moving it by hand, I can not move mine by hand only with the control.
Mike Palmer make sure the carbs are done right and its synchronized correctly, good plugs and wires and of course even compression and hope your reed valves are good. as for lower unit check your linkage with the lower unit off to eliminate that it is not the problem before you rebuild the housing.
Can anyone tell me what that grey fabric type ground? is and exactly what its for. I have same motor and mine is just hanging there..I am assuming its for the starter as the starter was all messed up and I replaced it and was missing bolts. but was not connected before i fixed so just left it.Motor runs great. just curious as hell.
I believe you are talking about the ground wire that screws to the shroud bracket . its there to ground it because it is mounted on rubber for vibrations.
@@smedsmarineland Thanks !
I have a 1975 too but i just have coils no distributor, my tell tale comes from the top of the motor too. Why the hose from the mid section to the fuel pump?
I'm wondering the same on mine you ever take it apart
Actually, I believe in 1977 the 65 hp was dropped and replaced by the 70 hp model. I personally own a 1976 65hp, a 1977 85hp and a 1976 9.8hp. I'm currently collecting, I hope in time, the full lineup for these bicentennial Mercs. ;)
Excuse me sir I have the same exact motor I have a question about it if you're still doing this and you're still available
Ask away and Ill try to help if I can!
What about how to clean the carbs on this 65 hp motor ?
To clean them properly they must come off.record the jet settings before they are dismantled. Soak them in a good carb cleaner for overnight. Check that the floats actually float and rebuild. I strongly recommend using a service manual and Mercury parts.
Donde puedo conseguir el modulo cdi
Ebay or a place on the internet Ive used called BAM
The cowl is a 76 but the engine still has a distributor so it's pre 76.
You are correct, the cowl is either a 76 or 77 (only 2 years this style) and sin comes out as a 75
I have the exact same engine my 74 Tri Hull
2 stroke right?
Yes it is
Where are you? You should work on my boat motor
Im in Ontario Canada but I have no more time to work on motors. Ive been trying to find a couple hours to get my boat going for the last 3 years LoL
I'm pretty sure it's a 1976 vintage Merc
idle way to high.