Engine Oil changing and sucking it out via small dia tube

[baz]

I have a real problem understanding how sucking old oil from the engine using a very small diameter tube inserted down the dip stick casing can get all the oil sludge out. This is very unlike changing oil in a car's engine where there is typically a large diameter drain plug in the belly pan that allows all the oil crud to freely exit.

I know the oil typically is or should be warm before attempting to suck the oil out and this would mean some of the oil sludge/crud is mixed up with the oil being sucked out... but

It would seem to me that for the boat's engine, the oil sludge that does not get removed by the 'drain tube sucking' method builds up over the years.

If I'm correct it would seem that at some time an extra maintenance chore will/might be required to really clean out the engine's oil system.

Comments ?

 

[Texas Steve]

Baz:

I'm with you. I tried it this season and didn't think it worked very well. I am sure there are others here that can help us sort out how to do this more efficiently.

Texas Steve

 

[Nellie Too]

Barry,
If you warm up the oil before you pump it out it will be filtered by the oil filter and be more easily removed. There will always be some sludge but your filter will continue to clean the oil in normal use. This is why it is critical to change the oil and filter once a year (at least).
Bob

 

[Lobo]

I've changed oil on my 110 HP Yanmar by sucking it out with a vacuum pump.

I could only get 3 litres. Drove me nuts. Stupid pump! I thooght I had pushed the tube so far down that it has curled back up above the oil.

After a re-read of the manual, I find out that there is 3+ litres of oil between the "low" and "high" marks on the dip stick. As I was at the low end of the dipstick, just over 3 litres was all the oil that was in the crankcase.

Now my vacuum pump isn't as stupid as I thought.

Dave

 

[markm]

I had a marine service change my oil every year, but they went out of business. I have the pump that you insert down the dip stick. I have an R21 with the small diesel (27 hp), how much oil should come out and what type is recommended? 10W-50, etc?

Thanks

Mark

 

[Levitation]

On an engine that receives oil and filter changes at the recommended intervals there will be no 'sludge'... Changing the engine oil while it is hot is the universal method of ensuring that the bottom of the oil pan is scrubbed clean at the time the oil is drained...

Even the boat engines that drain from the bottom do not drain completely - my Cummins 150 will drain 4.5 qts of the claimed 6.3... If there was an easy way to tip the boat forward to overcome the engine being mounted on an angle plus the bow riding up, to bring the oil pan bottom dead level with the drain plug, then it would drain most of the rest - but there isn't <shrug>... Simply changing the oil more often than the recommended interval is your best method of overcoming the fact that there will always be some used oil left in the pan after each oil change...

One method I have seen used at times on an aircraft fleet flown in dusty conditions is to change the oil every 25 hours, (normally 50) and the oil filter every 100 hours (normally 50)... The rational here is that since the oil is being kept cleaner on average by the more frequent changes, the filter is not having to remove as many contaminants and therefore will easily go the extra hours... These $50,000 engines went the normal time between overhauls despite the severe operating conditions so there was a method to their madness

cheers

 

[commander bill]

At the end of last season I changed the oil in my R25 after warming the engine while boat was on the trailer. It took about 15+ minutes to get engine to about 150 degrees. I was able to "suck" only about 4 1/2 quarts of oil with my pump. I then waited for a few hours until engine comletely cooled. I also do not like to leave any old oil or residue in oil pan but I also did not want to drain hot oil into bilge. I then removed the oil pan drain plug (boat trailer elevated at front with boat drain plug removed and pan under drain hole on ground to catch oil). I got about 2 more quarts out this way. Bilge was then cleaned with soap & water to look as good as new. I would rather drain oil warm but not onto fiberglass hull.

Before this fall I intend to obtain one of the brass oil pan drain valves (Japanese brand, I forget name but I have them on my vehicles & they work great). These come with a tube fitting and could offer us the ability to drain the final 2 quarts when changing oil on a boat in the water. Our engine is not listed on the website for these drain valves but our drain plug threads match several of their drain valves.