7.4 L Mercruiser Oil Consumption Problem
07-18-2007, 04:44 PM
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7.4 L Mercruiser Oil Consumption Problem
To any savy engine mechanic,
Am owner of twin 330 HP 7.4L Mercruisers, '95 vintage with 900 hrs of which the starboard engine has recently begun using too much oil.
Last week I traveled aproximately 3 hrs and used 2-3 qrts of oil...engines were at 1000 rpm during the trip. My compression check revealed 3 low cylinders ranging between 90 - 120 PSI. This engine had suffered a blown oil cooler at 3400 rpm and was promptly shut down. Some upper valve (lifter and rocker arm) squealing was noted after oil replenishment and upon startup but disappeared shortly after ignition. Heads are currently in shop to see if valve guides are the problem. After the initial compression check another one was perfomed where engine oil was added to each low cylinder to see if pressure changed...none was noted.
Any chance of this problem being a ring (IE Oil).
Thanks in advance for some sage council...I hate to have to pull that engine again.
Don
Am owner of twin 330 HP 7.4L Mercruisers, '95 vintage with 900 hrs of which the starboard engine has recently begun using too much oil.
Last week I traveled aproximately 3 hrs and used 2-3 qrts of oil...engines were at 1000 rpm during the trip. My compression check revealed 3 low cylinders ranging between 90 - 120 PSI. This engine had suffered a blown oil cooler at 3400 rpm and was promptly shut down. Some upper valve (lifter and rocker arm) squealing was noted after oil replenishment and upon startup but disappeared shortly after ignition. Heads are currently in shop to see if valve guides are the problem. After the initial compression check another one was perfomed where engine oil was added to each low cylinder to see if pressure changed...none was noted.
Any chance of this problem being a ring (IE Oil).
Thanks in advance for some sage council...I hate to have to pull that engine again.
Don
07-23-2007, 08:33 AM
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Mike,
Machine cheked out heads and all the guides are fine as are the valve guide seals. I am now really puzzled but am wondering if a recently installed new engine oil cooler could have a small leak and is the reason I see a sligh oil slick in exhaust water...any recommendations?
Thanks in advance
Don
Machine cheked out heads and all the guides are fine as are the valve guide seals. I am now really puzzled but am wondering if a recently installed new engine oil cooler could have a small leak and is the reason I see a sligh oil slick in exhaust water...any recommendations?
Thanks in advance
Don
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