Senior Tech Team
Join Date: Sep 1998
Location: Mustang, OK USA
Re: Coolant mysteriously disapearing
Let me tell you about a personal experience that took several years to locate and fix.
I built the persent SB400 that's in the 70 back in 1998. After 4-5yrs, the coolant level in the radiator went down slightly---------not much. In time, it went down in an increasingly shorter period. I checked EVERYTHING, including replacing hoses and taking the radiator to the shop. NOTHING. Nothing out the tail pipe, nothing on the driveway. ZERO indication anywhere of a leak! No water in the oil, no oil in the coolant. And the engine always ran fine. One day (I do not know why), I decided to pull the plugs. BINGO, a tiny bit of water dribbled out of #2 hole. I pulled the intake and the right head. The chamber and piston were VERY clean------------------as in steam cleaned! I could NOT FIND the source of the leak. FINALLY, I noticed a tiny light colored path in the #2 combustion chamber between the valves. To make a long story short, it was a VERY TINY pin hole (had to use a magnifying glass to see it) which me and my machinist decided was a casting flaw where the metal in the roof of the chamber (on the water jacket side) was EXTREMELY thin and the tiny pin hole had developed. I rounded up a matching head, had it machined to match the other head and put it all back together. This occured about 3yrs ago. Haven't added an ounce of water since.
Light travels faster than sound. That is why some people appear to be bright until you hear them speak. (unknown)