Cooling System Water Flow

[Speple`]

I have recently purchased a 1975 27' Catalina with a raw H2O cooling system (My first engine of this type on a sail boat usually have an outboard). While moving my new purchase to my marina I ran into some overheating problems. My first issue was as we were motor sailing she heeled over exposing the H2O intake port and created an air lock in the intake hose. As soon as I noticed that the engine hit 200+ I turned her off. Ever since then I have had issues with cooling. I have removed and inspected the impeller where I noticed that the gasket was worn so I replaced it. I then followed the cooling Hose to the Thermostat (Periodically unhooking the hoses and running the engine briefly to verify good water flow) I have cleared all of the hoses and verified that there is good H2O flow before and after the thermostat. I then noticed that the port on the other end of the manifold was not receiving good H2O flow, but when I removed the Manifold drain plug I get water to come out. I am presuming that I have a blockage somewhere in this manifold plate. I have purchased a drill impeller pump to "Back Flush" this portion of the cooling system up to the thermostat as I cannot get any water flow out of the other end of the manifold other than from the drain plug. Are there chambers/ports underneath this plate that doing this would result in additional problems?
Thank you in advance for any information

[Don Moyer]

Not being sure what you mean by a "plate" in connection with a manifold, the aft outlet of the manifold is frequently blocked with sediment which can be cleaned out rather easily with a coat hanger, hack saw blade, etc. If you remove the elbow in the aft 1/2" pipe-threaded hole in the top of the manifold, you'll be able to tell at a glance if this is the cause of your blockage.

Don

[Speple`]

Cooling syatem Water Flow

Thanks Don,
I plan to pop down this weekend and take a look. I did although have the exhaust replaced last week. I will take it off and see what is in there. What I was referring to by the "Plate" the cooling portion on the port side of the engine that is connected by three bolts and attached to the carb. It looks like that if I take those three bolts off and detach the carbutator it will slide off. Am I correct? I did purchase your Overhaul book and it has helped immensely on numerous occasions.

[Don Moyer]

Sorry, but I still don't understand your description of a three-bolted plate attached to the carburetor having something to do with the cooling system. I may be having a senior moment (early signs of dementia, some might say) in which case hopefully one of our many Forum experts can step and save the day.

Don

[Dave Neptune]

port plate

I'm guessing the side plate on the port side ---case cover to get to the valves?---otherwise I don' see where anyone would attach a cooling anything to the carburateor which is not good around water!! The cooling passage access is on the starboard side or alternator-starter side.

Neptune

[sunnnnseeeker]

I think the concern here is the intake/exhaust manifold. It has 3 bolts and attaches to the carb or the carb attaches to the manifold. The manifold must be clear to allow water flow. Check it as Don suggests. Don't loosen the 3 bolts unless you have a new gasket on hand. I haven't seen that you know the block (water ports) around the cylinders is clear. Sounds like the entire cooling system needs a good flush.