Topic: Best/Easiest Way To Get Oil Back Into Tank After Wet Sumping

[Harsh]

I haven't ridden the bike for a while since I have been working on getting everything ready for paint.  The new oil stopper seal and spring thread that Elan has put together got me thinking about the best or easiest way to get the oil back into the tank.  MCRider posted saying that starting the bike like this could cause issues like pressurizing the lower end which pushes some oil up into the combustion chambers and fouls the plugs.  I do not want to cause issues where I will have to go back into the engine or start replacing more parts.

So what are we to do until we get the new stopper plug and spring?  Should I try using the kick starter to get the impeller spinning on the oil pump to move the oil slowly back to the tank?  Short 3-5 second bursts on the electric starter?

[martin99]

This is a common problem for those of us with old Brit twins!

Drain it out of the sump, then pour it back into the tank through a fine gauze filter.

[754]

 Start it...

[ekpent]

Start it...

+1.  Really I have never even given it any thought or ever worried about. Have never had a problem that I know of over the years.

[Xnavylfr]

I've had the same seep down on a CB. Just kick it over a few time before starting.. NOT really a big worry.


Xnavylfr(CHUCK)

[tlbranth]

Start it...

Not good if the tank is empty. Mine was and oil pressure was zero. I shut the thing off straight away.
Is Elan the guy who was going to produce the leak stopper? What's the story? I never saw anything else come of it.

[Harsh]

Start it...

Not good if the tank is empty. Mine was and oil pressure was zero. I shut the thing off straight away.
Is Elan the guy who was going to produce the leak stopper? What's the story? I never saw anything else come of it.

Yes Elan is the guy that is having the leak stopper produced.  He has a thread in the for sale section, which I just noticed you recently posted in.

[PeWe]

This was the first problem I thought I had back in 1979 when I had just bought the bike + fresh driving license. "The oil level is far too low, cannot see the oil!!" A friend of mine laughed a lot and told me that this is normal when cold.
I started the bike .... magic... the oil was back.
If the engine has been not started for long time I usually kick or starter + kill switch run the engine to ensure oil everywhere before start.

[754]

I have to look over the oil flow diagram , but I think pump also draws from sump thru screen.
  Anyway kick. Over a bunch of times is good idea if tank is low.
 At one time in a custom frame my oil overflow tube broke off in the custom tank. I would lose pressure at idle unless i stood it up as all the oil was in the sump, that or running back out of tank as fast as the 7/16 hole allows.
 That is how I ended up with an NOS pump, it took a bit of time and opening a pump or two , before I realized... Why I had no pressure when bike was on sidestand.

 If  on a stock bike, tank had completely drained, and bike fired right up, the oil pressure should come up within around 2-5 seconds, I am thinking..

[lrutt]

I've never heard of an SOHC dry sumping. that is new.

But, regardless, if the tank fed to the pump is exposed to air, I don't care what you do, that pump is sucking air, and that can't be good. I'd drain the sump and fill the tank. Not to mention the risk of blowing seals or having the crank froth all the oil up in the sump. There is no good to come of leaving 4qts of oil in the sump. Sorry.

And you will not pump all that back with a few kicks or a few seconds on the starter, think about it. How long it takes just to pour that much into your oil tank.

And check valves in the intake line are just NOT a good solution either. If possible, fix the problem. It has to be a very rare occurance. neither of my 750's have ever sumped. Niether of my old Triumphs have every sumped. The only bike I've had this happen to is the Norton and the fix is rather expensive. So If the tank level is below the intake screen, I drain and fill. Simple as that. You can't assume just because the crank is whipping through oil that all will be ok. More critical is that the Cam is getting fed.

[754]

Actually I think the oil pump always draws from sump first, then when pressure builds to a preset level...and only then..the check valve opens..and only then while already running..does oil from the tank enter the pump..

[74750k4]

Yes, but that dirty draw from the sump to the re-fill pump is sent to the tank, and tranny. If there is no oil in the tank, then you're feeding air to the main system pump that provides oil to the filter, and then the bearings. When it's started empty, or close to it, (not a normal dry sump condition) the tank has to fill, faster than it gets drained, or you get zero oil to the bearings...
Trust me, I've seen the oil light come on in this condition.

[754]

I fir a period of weeks had to start up with all the oil in the sump, and keep it upright at idle to maintain pressure.. Did not seem to hurt it. Run a gauge and watch it. crank it over before startup if tank is dry..or put in small amount of oil , like 1/3 liter..

[Don R]

I guess it's like the old Castrol ad, starting your engine is a terrible thing to do.
 I'd say kicking, pushing or cranking it's still rotating slightly dry. For my decision it depends on how long it's been since it ran.
 
 On an old engine that's been parked or apart I fill the oil galley by gravity using a few pipe fittings in the accessory gauge port or I use an air conditioning oil cylinder hooked to the guage port to pressurize the oil system w/ compressed air over oil before starting it.

 An oil light for a second or two on a freshly lubed/ran  engine isn't going to hurt it, cranking for a long time on a dried out engine could hurt it. Common sense should be used in these cases,

[Xnavylfr]

DON,
Kicking or spinning the starter with MOST of the oil in the crankcase won't be a DRY start. The only problem is the crank has to spin with all that oil over it. With all the oil in the crankcase , the first thing the engine does is pull it through the strainer then through the filter on up to the top end.


Xnavylfr(CHUCK)
 

[Harsh]

For my situation the bike hasn't been ran for a month or two.  Right now I have just under 1/4" of oil showing on the dipstick.  This weekend I am going to kick it over a number of times and see what happens.  If I can get some movement of oil back into the tank I will continue with the kicking until I get a decent amount.  I should have my parts back from the painter by the end of the week so hopefully next week I will be riding...again!

[TwoTired]

You are over thinking this.  If you still have some oil in the tank, then just start it up!  The scavenge pump pumps faster than the pressure pump.  The pressure pump feeds the filter and then the oil galleys.  There is a diagram in the shop manual.  It's not going to starve for lubrication, just because the sump has more oil in it than normal.

[Bob Wessner]

For my situation the bike hasn't been ran for a month or two.  Right now I have just under 1/4" of oil showing on the dipstick.  This weekend I am going to kick it over a number of times and see what happens.  If I can get some movement of oil back into the tank I will continue with the kicking until I get a decent amount.  I should have my parts back from the painter by the end of the week so hopefully next week I will be riding...again!

A quarter inch is good to go. I'm admittedly paranoid. Over the winter, nothing shows on the dip stick, so before laying it up for the winter, I use a turkey baster and get a half cup or so of oil out of the tank after my last ride and put it back in the spring before the first start. As I recall from the diagrams, the oil tank is the first source of lubricant for the engine. During the riding season, I just start it up. Remember, I did say I was paranoid. 

[74750k4]

DON,
Kicking or spinning the starter with MOST of the oil in the crankcase won't be a DRY start. The only problem is the crank has to spin with all that oil over it. With all the oil in the crankcase , the first thing the engine does is pull it through the strainer then through the filter on up to the top end.


Xnavylfr(CHUCK)

On wet sump systems you are certainly correct. Oil goes from the sump/strainer to the pump/filter to the bearings. Not here.

If you follow the CB750 oil circuit diagram, you will see the correct path the oil takes...

1.) the sump pump starts sucking the sump through the strainer.
2.)the sump pump, pumps it up to the TANK, and directly to the tranny.
3.)the MAIN pump, sucks the tank down (if it's not dry), through the main pump gears, pumps it through the filter, the bearings, and then starts filling the sump up...
rinse, repeat.

[scottly]

if tank is dry..or put in small amount of oil , like 1/3 liter..

That's what I do: add enough oil to ensure there is an adequate supply to the pressure side of the pump. BTW, it can take a while for the scavenge pump to return the oil from the sump to the tank, like 5-10 minutes or so.. 

[754]

It may take some time to bring it all up,but it should start covering the pickup hole in within 10 or 15 seconds..just dont rev the snot out of it.

[lucky]

I've never heard of an SOHC dry sumping. that is new.

But, regardless, if the tank fed to the pump is exposed to air, I don't care what you do, that pump is sucking air, and that can't be good. I'd drain the sump and fill the tank. Not to mention the risk of blowing seals or having the crank froth all the oil up in the sump. There is no good to come of leaving 4qts of oil in the sump. Sorry.

And you will not pump all that back with a few kicks or a few seconds on the starter, think about it. How long it takes just to pour that much into your oil tank.

And check valves in the intake line are just NOT a good solution either. If possible, fix the problem. It has to be a very rare occurance. neither of my 750's have ever sumped. Niether of my old Triumphs have every sumped. The only bike I've had this happen to is the Norton and the fix is rather expensive. So If the tank level is below the intake screen, I drain and fill. Simple as that. You can't assume just because the crank is whipping through oil that all will be ok. More critical is that the Cam is getting fed.

The CB750 IS a dry sump system.