jgoedd99
Active Member
I just received my oil analysis reports and Blackstone Labs suspects I have coolant showing up in the oil. Engines are Mercruiser, 7.4 liter MAG MPI Horizon 380 HP w/ Velvet Drives with closed cooling. The boat is a 370 DA used in freshwater its entire life and has 700 hours on each engine with no major engine work done previously. This is my 2nd year of doing oil analyses on this boat and results this year are similar to last years (no worse). There continues to be high sodium in both engine oil samples. Starboard sodium result is 128 ppm and port is 48 ppm. Starboard also shows 0.26% antifreeze in oil. All other oil analysis parameters are acceptable and there do not appear to be any other wear issues. The oil sample was collected at end of this season and had 40 hours of use on it. Boat is winterized and stored for winter.
During this boating season I added about 16 to 20 ounces of antifreeze (50/50 Dexcool) to the coolant reservoir to replace “missing” antifreeze in the starboard engine. Similarly I added about 12 ounces of antifreeze to the port engine coolant reservoir. There is no “milkshake” appearance to the oil, and there is no oil showing up in the coolant. Neither engine has any external coolant leaks to explain the “missing” antifreeze. I suspect that antifreeze leaking to oil is evaporating as the engine is run because oil does not show milky appearance and is not increasing in volume.
Last year I elected to monitor the situation. This year I am going to ask for some advice and see what the knowledgeable CSR members think the problem is and get an idea what the cost may be for the dealer to repair. I normally do all my own maintenance but draw the line at taking an engine apart.
Assuming this ends up being a head gasket, it probably would be a good time to have the exhaust system inspected because all that has to come off to get to the head gasket, no?
Thanks for any help or suggestions. If it would help to see the oil analysis reports, send me an email at nickett723@roadrunner.com and I will send you the PDF reports for the two engines.
John G
During this boating season I added about 16 to 20 ounces of antifreeze (50/50 Dexcool) to the coolant reservoir to replace “missing” antifreeze in the starboard engine. Similarly I added about 12 ounces of antifreeze to the port engine coolant reservoir. There is no “milkshake” appearance to the oil, and there is no oil showing up in the coolant. Neither engine has any external coolant leaks to explain the “missing” antifreeze. I suspect that antifreeze leaking to oil is evaporating as the engine is run because oil does not show milky appearance and is not increasing in volume.
Last year I elected to monitor the situation. This year I am going to ask for some advice and see what the knowledgeable CSR members think the problem is and get an idea what the cost may be for the dealer to repair. I normally do all my own maintenance but draw the line at taking an engine apart.
Assuming this ends up being a head gasket, it probably would be a good time to have the exhaust system inspected because all that has to come off to get to the head gasket, no?
Thanks for any help or suggestions. If it would help to see the oil analysis reports, send me an email at nickett723@roadrunner.com and I will send you the PDF reports for the two engines.
John G
