Oil leak

[Reinhoud]

Gentlemen, I've got a problem what doesn't makes sense, or; I can't find the logic..

 

I'll try to discribe it as wel as possible. Can take photo's if it's not clear enough.

 

Problem;

Whenever the bike is parked after use, after about  1 or 2 days an oil leak develops, it's getting worse the longer it's parked. The oil comes from the scavenge tank.

The scavenge works fine, sucks more oil up as what the turbo can give it.

Scavenge tank holds about 300cc.

The thing is; oil keeps dripping from the turbo after about a day, and it doesn't make sense why.. The scavenge catch tank is big enough to hold the oil from the turbo and the oil feed line.

 

The setup;

Because of the rollerbearing crank I made an oil feed pump for the turbo, and an oil scavenge pump. The scavenge pump is bigger then the feed. The scavenge sucks up more oil then the feed can provide.

The feed pump is on the pottom of the sump, at the lowest point of the engine.  Because of this the oil would start leaking through the pump into the turbo.

To solve this problem  I made a loop in the oil feed line, this loop is about 4cm above the oil level.

The scavenge pump is also above the oil level, so it can't be leaking from there

I don't think there can be any pressure in the crankcases, breathers are big enough.

 

 

The only thing what I can think of is the oil feed line, but it has that loop in it, and the top of the loop ends up about 4cm above the oil level, and when there's no pressure in the crankcase, nothing can be pushed out... ??

 

Anyone who has an idea what might cause this?

Feel free to ask questions if it's not clear enough.

 

Thanks

 

 

 

[Arttu]

I think the loop on the feed line may not be enough to stop leaking through the feed pump. When the line is full draining oil will suck oil from the pump even over the loop since air can't get into the line.

Adding a check valve on the feed line should prevent this.

[Gixer1460]

I think ^^^ nailed it - the effect is called a syphon, and it will continue once started until air enters the 'inlet' side. Law of Physics can be a bastard sometimes LOL!

[Reinhoud]

Damn, that's something I didn't think of!!!

 

Would a check valve do anything? Because the oil keeps flowing in the same direction?

 

 

Thanks!

[TLRS]

What does the scavenge tank do that a sump can't? Sorry if it's a dummy question..

[Reinhoud]

1 hour ago, TLRS said:

What does the scavenge tank do that a sump can't? Sorry if it's a dummy question..

It's needed because the turbo is below the oil level.

The scavenge tank catches the oil from the turbo and lines after the engine has been turned off

[Reinhoud]

I've been thinking for a solution of my problem, the only thing I can come up with a loop in the suction part of the oil pump, the loop goes above the oil level.

 

Anyone who has a different / better idea, please let me know.

 

Thanks

[Maggotbreath]

Check valve you need has a 1psi cracking pressure. or rather when oil system pressure is zero psi the valve closes and seals any flow.

This is the one I used. Same issue as you [dripping when off] and also smoking at start up. both solved .

https://www.rbracing-rsr.com/oilsystems.htm scroll down, ignore the electric oil pumps. their huge!

part number

03-1039

FYI... RBR are the boys that figured out how the Yami turbo worked and launched the diy CV carb'd Turbo revolution!

 

Finally, as you know, I've been following your progress from the beginning. Awesome work, especially your oil pumps, kudos! How the hell did you dream that stuff up?!!!!

Edited October 26, 2022 by Maggotbreath
more info

[Arttu]

6 hours ago, Reinhoud said:

Would a check valve do anything? Because the oil keeps flowing in the same direction?

Yes, like @Maggotbreathsaid the check valve needs certain pressure to open. And siphon effect can't create that much pressure so flow will stop when the oil pump stops.

[Reinhoud]

Thanks guys!! Much appriciated!!

 

I was just thinking, a loop in the sucktion doesn't do anything either I guess..

[Reinhoud]

4 hours ago, Maggotbreath said:

now, I've been following your progress from the beginning. Awesome work, especially your oil pumps, kudos! How the hell did you dream that stuff up?!!!!

Hehehe. that took a while, the initial idea was there pretty quick, figuring out how to do it, how to drive it was the challenge.

It's about 50% thinking of it before you start, 50% design as you go.

Running out of other options was probably the main thing to do it like I did it..

[Reinhoud]

I did an attempt to order the check valve..

[TLRS]

18 hours ago, Reinhoud said:

It's needed because the turbo is below the oil level.

The scavenge tank catches the oil from the turbo and lines after the engine has been turned off

Would just a scavenge pump do if it's kept running for a bit after stopping the engine?

[Reinhoud]

7 hours ago, TLRS said:

Would just a scavenge pump do if it's kept running for a bit after stopping the engine?

Most likely.

But you have to go electric then

[TLRS]

On 10/27/2022 at 4:07 AM, Reinhoud said:

Most likely.

But you have to go electric then

Couldn't resist taking a quick peek. Searching for automotive delay timer, relays turn up with for instance a 10 sec delay. Maybe it could simplify your setup (:

[Gixer1460]

The geezer uses a mechanical scavenge pump though!

[Reinhoud]

Got the check valve in the other day. 

Also got the connections to install it in the feed line, now find the motivation to put it in

[Swiss Toni]

Is it done yet then???

[Maggotbreath]

9 hours ago, Swiss Toni said:

Is it done yet then???

What he said     

[Reinhoud]

9 hours ago, Swiss Toni said:

Is it done yet then???

No pressure at all...

 

 

[Reinhoud]

This is the valve

[Maggotbreath]

That should fix your smoking issue. Originally my catch can was too small and it still smoked, my line volume was greater than the tank. I see your tanks is 300 cc, that's huge. If ya calculate the line volume between the check valve and the tank ya might be able to go with a smaller tank. My tank is aprox 6cc

[Reinhoud]

10 minutes ago, Maggotbreath said:

That should fix your smoking issue. Originally my catch can was too small and it still smoked, my line volume was greater than the tank. I see your tanks is 300 cc, that's huge. If ya calculate the line volume between the check valve and the tank ya might be able to go with a smaller tank. My tank is aprox 6cc

It's not smoking, it starts leaking after a couple of days.

The tank is that big because I thought it wasn't big enough, this is the 3rd tank, bit bigger every time.

[Maggotbreath]

7 minutes ago, Reinhoud said:

It's not smoking, it starts leaking after a couple of days.

The tank is that big because I thought it wasn't big enough, this is the 3rd tank, bit bigger every time.

Right! mine did that to and smoked on start up. Yours is of course quite a bit different. With both your oil feed and scavenge pumps lower than the oil level you might also need a check valve on the scavenge side? If you disconnect the scavenge line from you tank will the motor drain?

[Reinhoud]

When the bike is straight up the scavenge is above oil level.

 

In the past I did have a check valve in the line, but they always stuff up after a while, and I don't think the scavenge sucks hard enough to open the check valve I have now...