Overheating Problem on Renault Deisel

[Jim Arrighi]

I have a 1980 Hunter 27 with 8hp Renault deisel. It normally runs quite cool. I then had a problem with overheating, and found that the cooling line was plugged at the steel nipple where the water line joins the exhaust. I cleaned it out with a screwdriver; it seemed plugged with black gunk (for lack of a technical term). The engine ran normally, but after about 2 weeks, overheated again. The line was again plugged at the same point, and I cleaned it out. Does anyone have any idea why the line gets plugged at this point? Is there anything I can do to prevent it?

 

[John]

Could be carbon build up

I recently replaced that exhaust elbow and it had a good amount of black soot (carbon?) coating the inside. It could be, after 22 years of use,that the sludge is moving over the hole. Does the water line itself, show any black stuff in it? Try tracing the water lines back. Could be the lines rotting on the inside. You can also take off the exhaust elbow and check it out. You may have to make a new gasket to reinstall it. I found the gasket material at a car parts store. Recently I found some shell material in the T-valve that is right behind the engine. Becareful taking the water lines off the T-valve. I broke mine and had to have a new one made out of metal. My rc8 is one of my full time hobbies.