Mercury 650 tbolt ignition

[hdawg]

I have a 1975 or 1976 (not sure need to check serial number) mercury 65hp 3cyl. I recently replaced the lower unit which fixed my previous problem. Now I have a new problem. After about 1/2 hr of run time with my new lower unit, the engine stalled and would not power up. By that I mean it would idle(very rough) but would not run at throttle speed. I pulled the motor hood and found that water was pumping from around the top spark plug. I'm assuming a blown head gasket or a cracked cylinder. Someone told me this motor may not use a head gasket as I could not find a listing for one. Can someone help me here? Head gasket? Cracked cylinder? Other? All help appreciated.

 

[rickdb1boat]

Re: Mercury 650 tbolt ignition

Yes, it will have a head gasket, that could have blown. You will need to pull the head to find out. Here is a link for Parts and other Merc. info! You will need serial # to order parts and look up other items. They are the same site, but one directs you to the Head Gaskets. Good Luck!<br /><br /> Head Gaskets <br /><br /> Merc Troubleshooting site

 

[aeronutt29]

Re: Mercury 650 tbolt ignition

Rick, The link you posted suggests that there isn't a head gasket since no part number is listed. <br /><br />On my 6 cylinder merc, the gasket around the spark plug hole is for the water jacket cover. I don't see how this gasket going bad would affect the power output unless it was pumping so much water out that the engine overheats. The first thing to do is get the water leak stopped by pulling the cover off and replacing the gasket. Next trick is to make sure the water pump is pumping all the water that it should. If you didn't replace the water pump impeller while you were changing lower units then you should kick yourself in the butt a few times and then go buy an impeller.

 

[hdawg]

Re: Mercury 650 tbolt ignition

aeronutt,<br /><br />Thanks for your input. I did change the impeller, in fact, the entire unit was rebuilt (bought it from iboats.com). I pulled the water jacket cover. Gasket seemed to be damaged. Bolts holding cover on were really rusted up. Will replace this gasket and go from there. Thanks again.

 

[rickdb1boat]

Re: Mercury 650 tbolt ignition

Maybe this one will clear up what I was thinking!

 

[rickdb1boat]

Re: Mercury 650 tbolt ignition

 

[hdawg]

Re: Mercury 650 tbolt ignition

rick<br /><br />not sure what you mean. did you intend to list another website?

 

[rickdb1boat]

Re: Mercury 650 tbolt ignition

Never mind previous post! Sorry!

 

[hdawg]

Re: Mercury 650 tbolt ignition

thanks rick<br /><br />how did you do that. isn't that the same site as before?

 

[hdawg]

Re: Mercury 650 tbolt ignition

rick<br /><br />can you send that last (head gasket) site again. it seems to have disappeared. thanks

 

[rickdb1boat]

Re: Mercury 650 tbolt ignition

Not head gaskets, but may help with others! Gaskets