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Mercruiser 470 oil in coolant tank

copierkat

New member
Hi all. I started my recently purchased 83 Celebrity with 470 Mercruiser for the first time tonight. I only ran it a few seconds with muffs a couple times and shut it off. I went into town to rent a compression tester because one of the plugs came out clean when changing them, like there was a coolant leak into that cylinder. Before starting with comp test, I added anti-freeze to the tank on top since it was empty. After filling it, it looked dirty brown, and when I stuck my finger in it, it was oily. Also, there is no oil on the dipstick, although it was clean and on the full mark last fall. I do not want to start the comp test with oil in the coolant. Should I drain it and re-fill? What kind of oil should I put in this engine? Can I use 5W30? Dave
 
Should really check the oil ,the A/F level and the water in the batteries before starting.
Needed some oil for my truck and your boat was the closest.I prefer 20W -50 for my truck
 
if its #4 plug, that could be from a leaking riser. check the oil level and add if necessary.fill A/F to the cold level.
run engine to operating temp.Let cool and recheck all fluids.
 
if its #4 plug, that could be from a leaking riser. check the oil level and add if necessary.fill A/F to the cold level.
run engine to operating temp.Let cool and recheck all fluids.

OK, the compression test from bow to stern was 105, 110, 105, and 120. Are these OK? Will do cooling system pressure test next. Dave
 
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