Ive got a 90 honda , the engine oil was milky , it was running bad so I did a compression test and found # 3 cyl was low it was also overheating so I pulled the cyl head . There is a 2 inch hole between the exhaust and water jacket , the head gskt seemed ok . Could there be a cracked block , could I weld the hole closed or is it not worth the risk ? Any ideas ?