OK - After changing the sea water pumps on the Eliminator last night I fired it off to scan it and check for leaks. I noticed a 'whisting' from the vent hose from the valve cover - there is quiet a bit of vaccuum on that hose. So I fired off the other motor - and it also has vaacuum at idle - but not as significant. Is it common for these motors to have a vaccuum on the valve cover vent hoses at idle???