need cooling system help

[f_inscreenname]

Dose any one have a diagram of a 1972 I/O s/b Chrysler's raw water cooling system? Mine starts with a screened hole in the bottom of the boat then goes to a raw water pump on the front of the motor. From there I think I got it right but I am not sure. I blew out my second freeze plug today. The last one was behind the flywheel (when I fixed it I JB welded them in to make sure if one comes out again it wouldn't be those two). I know there is a problem some where so if I can prove to my self the cooling lines are the right size and going to the right place then its time to look else where (freeze plugs,raw water pump I am pulling 320hp out of the motor maybe the pulley spins to fast making to high water pressure when the thermostat is closed?). But never seeing a Chrysler marine cooling system and not being able to find one I am just guessing. <br />PS Every thing is new this summer (motor,ex mans,cooling system) except the raw water pump it came off the 318ci that I replaced with a 360ci. I have pictures of the old motor before I took it apart but the last owner had the cooling system so jury rigged up they are no help.

 

[nrladeere]

Re: need cooling system help

I don't know the specifics of your system, but in general the raw pump is a positive displacement pump at low to moderate sppeds. When the thermostat is closed there must be a bypass for the water. Usually there is a line to the exhaust riser and or a bypass oriface to the manifold usually inside the thermostat housing. If the raw water impeller has ever deteriorated or there is trash or debris in the system these 2 outlets could be plugged and the pump will build pressure until a hose or plug lets go.

 

[f_inscreenname]

Re: need cooling system help

I got drawing on another board of the cooling system. Everything is right and everything is new or rebuilt and inspected. The hoses are going to the all the right places. I have only have had this problem since I have been running a thermostat. I am going to drill a couple holes in the thermostat to relive pressure when it is closed and see what that dose.