Letting Oil Drain Out for a week

[Compass790]

Originally Posted by Wotname

Really!

Not saying you are wrong, just saying I haven't seen a magnetic sump plugs for ages. Most engines I am familiar with don't have any ferrous parts in them to wear - gearboxes are a different story.

Can you let us know where you have seen them - last one I saw was in a BMC mini?

Once again, for the OP, his QM engine does have a suitable plug for a pre-oiler pick up - an external plug that uses the existing internal pickup as it's source. The pressure side (or return) goes into the oil switch port which IIRC, is just before the filter. It's a win / win!

Hmmmm no ferrous?? crankshaft, cam gears,tappets.....

[Wotname]

^^ well yes but the wear is mostly in the bearing material, not the ferrous bits.
The small amount of ferrous material ends up in the filter or sitting in the sludge in the sump .

For a magnetic sump pump to work properly to pick up small amounts of ferrous material, the oil would have to wash over the plug.

I have seen parts of gear teeth on magnetic sump plugs :roll eyes:

Just recently I did find some ferrous material in a sump - a Stanley knife blade!!!!

[Compass790]

Originally Posted by Wotname

^^ well yes but the wear is mostly in the bearing material, not the ferrous bits.
The small amount of ferrous material ends up in the filter or sitting in the sludge in the sump .

For a magnetic sump pump to work properly to pick up small amounts of ferrous material, the oil would have to wash over the plug.

I have seen parts of gear teeth on magnetic sump plugs :roll eyes:

Just recently I did find some ferrous material in a sump - a Stanley knife blade!!!!

Thats why i put neodymium magnets on the oil filter so there is constant wash past but I haven't bothered to check if they trap anything. but I have seen stuff stuck to magnetic sump plugs just as i have seen worn crankshafts etc etc. But each to his own.

[Allied39]

Pics are attached. Sorry, not rotated correctly. the pump is installed so the writing is horizontal.
One of the check valve fitted. Blue hose is coming from the pump into check valve then connects to tee into the pump below filter.

Other pic is of the pump itself. Left of pump is the control module.

[odonnellryan]

Originally Posted by Wotname

For the OP.
FWIW, you have a poor man's pre-oiler already with your 3QM30 engine. If you wish to take the trouble, you can operate the decompression levers before starting. Let it spin over decompressed for say 5 secs. Then start by dropping the decompression levers. This get oil pressure up and oil circulating without any significant load on the bearings before starting. It also decreases the electrical load on the starter motor.

When I was dealing with issues on the fuel line and air intrusion (crush washers ... ) I found out that if I flip the decompression levers and run to prime the fuel (found online this was OK to do) after about 5-10 seconds the levers actually flip back and the engine will turn over.

I imagine this is not harmful? And if I felt like it, I could just go below, flip them, then turn over until they flip back after 5-10 seconds?

I like the 3QM30 because I can also turn it over manually to prime the fuel lines, check the water pumps, belt, etc.. and even start it I suppose (though I haven't tried).

[hellosailor]

Bear in mind that oil and engine technology changes over time. Synthetic oils, exotic in the 1980's but found everywhere today, are usually reformulated to have outstanding thin-film properties, which conventional oils even in the 1980's did not and could not have. This is important because during the first two or three revolutions of a "dry" crankshaft (i.e. one that has been sitting overnight or all week unused) the shaft literally slams across in the bearings, as each piston rod pushes it in a new direction. And it slams basically unlubricated. This is one reason why long-haul operators idled their engines and did not shut them down during hour-long stops. (No stops=no starts="no" wear.)
The same thing applies to piston rings and cylinder walls. The old oils just ran off the metal, leaving the cylinder walls and rings unlubricated after a stand-down.
The synthetics, starting in the 80's, were reformulated so they remain on bare metal, leaving a lubricant coating for days or weeks longer than conventional oils. Apparently, when you are building oil molecules, you can more easily engineer them for this.
The new oils also have enhanced thin-film characteristics, so that when a part slams into a thin coating of oil, the oil does not just splash aside, enough remains to provide substantial lubrication.
You and I can't see this--but the oil company engineers can document it. And this type of "better" oil makes less of a need for pre-oiling, which used to be standard especially on aircraft and flying boats. Watch any old movie that shows a pre-flight checklist in the cockpit, early on there's an "oil pressure" or "oil pumps on" before the engines are started.
The problem is significant enough that before WW2 the USN, concerned about moving vehicles during an attack, issued a purchasing standard: Any seller who wanted to sell any vehicle (car, truck, anything) to the USN, had to build it in such a way that it had full operating oil pressure within 20 seconds, which was considered VERY fast at the time. And yes, since all of the auto industry (Detroit) wanted those Navy contracts...we can thank the USN for being able to just start-n-go now.

Prelube? Still a nice idea, especially if you don't run synthetics. Just nowhere near as important as it was on the 1940's aircraft.

[Wotname]

Originally Posted by odonnellryan

When I was dealing with issues on the fuel line and air intrusion (crush washers ... ) I found out that if I flip the decompression levers and run to prime the fuel (found online this was OK to do) after about 5-10 seconds the levers actually flip back and the engine will turn over.

I imagine this is not harmful? And if I felt like it, I could just go below, flip them, then turn over until they flip back after 5-10 seconds?

I like the 3QM30 because I can also turn it over manually to prime the fuel lines, check the water pumps, belt, etc.. and even start it I suppose (though I haven't tried).

You are correct, it is not harmful.

Another function of the decompression feature is that you can often get a start with almost flat batteries. With the engine decompressed, a weak battery will turn the engine over fast enough to build some momentum in the flywheel. When spinning nicely, drop one lever and that cylinder should fire, now drop the second lever and finally the third one.

[Icarus]

Originally Posted by odonnellryan

Hey all,

Just bought this boat and going to do the first oil change.

I'll have to see if I can access the oil plug (I think I can but I have to verify) but if so, is it OK to let the oil drain into a pan for a few days to a week?

Obviously if plug is not accessible I'll have to pump it out.

I figure it'd really let everything come out, but maybe not a good idea b/c of moisture etc getting up into the engine somehow? Or maybe that is not significant?

Vaccum pump it out...thtough the dipstick tube...refill and motor away...
Looks to me you should get more experinced about engine maintenance....

[Compass790]

Originally Posted by Wotname

You are correct, it is not harmful.

Another function of the decompression feature is that you can often get a start with almost flat batteries. With the engine decompressed, a weak battery will turn the engine over fast enough to build some momentum in the flywheel. When spinning nicely, drop one lever and that cylinder should fire, now drop the second lever and finally the third one.

wotname has given you good advice here. I do this as a matter of course for at least these reasons
1) Engine starts instantly on as rotation revs are higher when decompressed. May take an unfired compression stroke without decompressing on the rare occasion I've started without decpmpressing
2) Best practice to get oil pressure up before subjecting crankshaft bearings to combustion shockloads.( essential in my case as have non-std main bearings)
3) As he said less load on starter. We have a single cylinder so easy to do & i can't see any drawbacks except perhaps spraying fuel on cylinder walls & diluting oil film. Haven't seen any studies on that effect. If I was doing a PhD in mech engineering that wud b a subject for a thesis. But I'm way past that.lol

If yr decomp levers flip over automatically my guess is to do it as std procedure.

[a64pilot]

Oil pre-lubers were all the rage about the late 70’s, maybe early 80’s along with high bypass filtration and Amsoil. The idea was that most wear occurs at start up due to no oil pressure, so of course if you can negate that start up wear, your engine will last many times longer.
Unfortunately it didn’t come out to be true, apparently most wear doesn’t occur at start up, because pre-lubing didn’t significantly increase engine life expectancy.
The big ole aircraft radials had to be pre-lubed as you had multiple cylinders, up to 9 and thousands of cubic inches of engine running on one main bearing, and it needed oil pressure to float the bearing on and keep it from spinning on the crankshaft.

Most if not all hand start Diesels I have ever started have a decompression feature that lets you get some inertia into the engine and flywheel before compression hitting, decompressing an engine is very, very common especially on smaller single or twins, whether it be an outboard or a motorcycle, it doesn’t hurt a thing and may be kinder on the starting mechanism, but on a boat it may take two people and require removal of the engine cover, so I doubt it’s often done.

[RobPatterson]

Oil change after 2-days of motoring? Yikes. Well, let's hope we don't have to motor very much.

[Compass790]

Originally Posted by a64pilot

Oil pre-lubers were all the rage about the late 70’s, maybe early 80’s along with high bypass filtration and Amsoil. The idea was that most wear occurs at start up due to no oil pressure, so of course if you can negate that start up wear, your engine will last many times longer.
Unfortunately it didn’t come out to be true, apparently most wear doesn’t occur at start up, because pre-lubing didn’t significantly increase engine life expectancy.
The big ole aircraft radials had to be pre-lubed as you had multiple cylinders, up to 9 and thousands of cubic inches of engine running on one main bearing, and it needed oil pressure to float the bearing on and keep it from spinning on the crankshaft.

Most if not all hand start Diesels I have ever started have a decompression feature that lets you get some inertia into the engine and flywheel before compression hitting, decompressing an engine is very, very common especially on smaller single or twins, whether it be an outboard or a motorcycle, it doesn’t hurt a thing and may be kinder on the starting mechanism, but on a boat it may take two people and require removal of the engine cover, so I doubt it’s often done.

I'm curious A64, any studies on effect of pre-lubers on engine wear? Or is the evidence they made no difference anecdotal?
We have a decompression pull cable on the instrument panel next to the start key

[a64pilot]

I don’t know of any studies, reasoning is who is going to pay for the study?
Now a preluber doesn’t hurt, it was something that I used to really want, but then as I said they didn’t seem to make much difference.
Truth is it seems that in an automobile if an engine isn’t abused and is properly cared for, the car is going to be junk well before the engine is.
Wife’s Father has a Honda Accord I think, it has over 400,000 miles on it and doesn’t burn a drop of oil, car is in actually very good shape too.

When the cars that would shut themselves off at every stop first starting being made, I though that is stupid, these things can’t last very long, being shut down and restarted so often, and worse yet, as soon as they start, they are put under a load.
Every body knows that will kill an engine in short order, yet they seem to last, who knows how or why?

It would seem that a lot of our accepted “Facts” may not be?
Maybe back in the day of thick oils and super cold soaked auto’s in Michigan Winter or something is where the most wear occurs on start up started?

[Allied39]

My thought process was that to my way of thinking a pre oiler made sense for multiple reasons:

-Since a motor must have oil pressure when running, it's obviously better to have oil pressure before starting

-changing oil is a breeze, takes a couple of minutes without a drop spilled.

-since I love my motor and don't feel like dropping at least 10g ( i do my own labour) on a new motor I change my oil every 50 hrs, like the odds of the pre oiler being good for the motor and for the few hundred bucks I dropped was an absolute "No brainer" of a decision.

So, 1940's aircraft and synthetic oils did not even enter the thought process......huh, go figure?

[hellosailor]

"on a new motor I change my oil every 50 hrs, ...
So, 1940's aircraft and synthetic oils did not even enter the thought process......huh, go figure?"

Well, perhaps some engineering history is in order while you're throwing away all that oil. I was taught that a hundred years ago, if you wanted to buy a Rolls Royce, you had to also engage a properly trained chauffeur. And one of the *routine* jobs of a Rolls chauffeur was to disassemble the engine and hammer the soft silver metal bearings back into shape every so many hours.

Yes, you routinely remanufactured the bearings as part of routine operation.

Engines have come a long way since then. Even in the 70's or 80's the bearings certainly were more robust than bearings used to be. So, pre-oiling a marine diesel, or any other consumer or light commercial engine?

Might be more along the lines of buying a nice whole fresh cow every time you wanted a steak. And then throwing out the other 1800 pounds of beef because, well, you know, it wasn't fresh any more.

If you send out an oil sample for analysis after you've run the engine for one hour, and then you send out another sample when you do the 50-hour change, I'd be really sure that the samples would come back identical, showing a total waste of oil, unless you've got something like fuel or coolant contamination issues going on.

Or are you the fellow that's been listing "Gently used marine engine oil, good as new!" on Craigslist?