Mercruiser 5.7 MPI Horizon oil change - unable to extract all the oil

[Devil_Inside]

I have a 2005 Mercruiser 5.7 MPI Horizon and I am using a West Marine oil extractor with a garden hose adapter, but no matter what I do I can only suck about 3 quarts out, maybe 3.5 if you count what's in the oil filter. It is my understanding that the garden hose adapter is the preferred method since the dipstick tube is designed to to to the bottom of the oil pan, but I also tried inserting a long suction tube through the dipstick until it hit the bottom of the oil pan, and I still couldn't suck any more oil out. The boat is currently sitting on a trailer so I tried raising and lowering the bow, but that too didn't make a difference. After messing around with it for over an hour I sucked whatever I could, changed the filter and re-filled the engine with 4 quarts of oil. I ran the engine briefly and I checked the oil level and it was definitely higher than it should, and the oil looked contaminated. I am really stumped. I need to triple check with Mercruiser tech support, but I am pretty sure this engine has 4.5 quarts capacity, but this still leaves me at least a quart shy.

 

[alldodge]

Not very familiar with the 4.5, and this may need a call to Merc to verify. It could be to get all the oil, it needs to have a smaller tube pushed down inside the dipstick tube

Maybe @muc might have a better idea. Do you have a serial number

 

[Scott06]

count what’s in the filter too as the 4.5 qts probably includes the filter volume . I get 3.5 to 4 qts out of my 5.5 qt system on my 5.0, add a gallon the. Check the dipstick works just fine.

 

[QBhoy]

Ditch the threaded dip stick fitting and just do it rhe usual way with a vacuum extraction system that has a tube that gets to the bottom of the sump. You’ll get 99% of it out that way if you wait long enough for the oil to settle in sump after warm up...but not long enough that it takes forever to get it all out.