excessive oil consumption

[rudyard]

5.0L mercrusier just rebuilt with new pistons, rings and heads. Uses an excessive amount of oil. No leaks. Oils slick at idle and startup. What would cause this ?

 

[bobbyc]

What is excessive??? How long has it run after the rebuild??? Valve guides checked and seals replaced??? Oil return passages in cylinder heads unobstructed???

 

[guyjg]

Smell the oil on the dipstick...does it smell like it contains gasoline?

 

[rudyard]

I put about 50 hrs on last year and with new hr meter this year I put 52 hrs and used 7 qts of oil. This right after the rebuild. Heads have not been pulled. Didn't know if there were other possibilities.

 

[rudyard]

I used 7 qts of oil in 52 hrs run time. It was the same last year right after the rebuild. Oil is very black[ dirty] looking but no gasoline smell. Fuel consumption is the same as before rebuild.

 

[guyjg]

...just rebuilt with new pistons, rings...

Using 7 quarts in 52 hours is equivalent to about 3,000 miles on a car. Pull the spark plugs and post pics. of them. Pull the valve covers and see if they forgot valve seals. If needed, do a compression test to check the ring job.

 

[Docksidemarineservices]

Do a leak down test.