While winterizing my 1990 Volvo-Penta 4.3 engine I noticed no water drained out of the rt. exhaust manifold. I had plenty of water draining from the left manifold and both block drains. Would this indicate a water flow restriction that may cause overheating in the future? I had an overheating problem last year and replaced the impeller, t-stat and engine mounted water pump but didn?t find a positive cause for the overheating