There is actually only one coolant overflow and that is up by the pressure cap on the heat exchanger.
Are the lines you are referring to, down low on the block? If these are what you are referring to, these are the air box drains. You should never have any coolant coming out of these lines, only a small amount of oil drips.
If you have coolant coming out of these, you have some major problems. The problem may be a blown head gasket but not at the top of my most likely list.
Depending on the coolant maintenance history and how well it was adhered to will affect what I would put at the top of the list. The likely problems are a cracked head, cracked cylinder liner, perforated cylinder liner, and bad liner o-ring(s). Usually a blown head gasket will not give you coolant coming out the air box drains in the volume you are expressing or at least initially.
I would caution you that you also likely have coolant in the crankcase.
Before you get too excited and start tearing the engine apart, I would recommend to remove the air box covers on the strbd side of the engine.and see what is going on. You might need to pressurize the coolant system to aid in seeing what is going on. Use a bore scope to look inside of each liner through the ports and see where the coolant is coming from. You will need to rotate the engine over by hand to get each piston at BDC so the bore scope can go through the cylinder liner port that you are inspecting.
Bad liner O-ring will have coolant on outside of liner running into air box.
Perforated liner will give you coolant weeping as drops on inside of liner in various places.
Cracked liner will be an obvious crack with coolant leaking at the crack.
Cracked cylinder head will usually crack at the exhaust valve with crack extending to exhaust manifold side of head. Should observe coolant coming out of crack.
Blown head gasket will give you coolant coming in somewhere around the periphery of the head-liner interface. Usually a blown head gasket will put coolant into the crankcase before it has it running out the air box drains but not always.
The reason I suggested to do as I explained is so that you do nor miss something that will nor be obvious when you just pull the heads. Usually spending the time on the front end with problems as these saves you a lot of time and money on the backend of the project.
If your intention is to do an overhaul with new liners, pistons,etc. and possibly new heads, then you will be fine.
1800hrs is not that many and even though the engines are 50 yrs old, if they were properly maintained, the age shouldn't be an issue.
This gets back to your problem and I suspect that the engine got hot not too long ago. If this happened, it is likely that the liner O-rings are damaged in addition to a likely cracked head.
Matthew Avery said:
I am aware the coolant overflow line from the reservoir but at this point it is leaking at bottom of cylinder head and there are three lines running to an overflow box. I agree with your assessment that I have some issues on that engine I am going to pull heads tomorrow and then evaluate. I don’t have the time to fool with this and would rather fix it and be done with it. 50 year old motors and I knew I should have just rebuilt everything from the get go with only 1800 hours on them.