Oil drain leaf valve - which way round?!

[Swell]

I'm servicing my 1968 6hp Johnson seahorse and am confused as to which way round the oil drain leaf valve needs to sit and how to measure the clearance. The leaf valve has a slight bend in it and it is clear that if it is mounted with the bend inwards, the valve is permanently closed, but if it is mounted with the bend outwards the valve is permanently partly open.

Is the clearance referring to the distance between the leaf and the crankcase block with the leaf valve in the 'permanently partly open' position?

It was originally mounted 'bend in' so was permanently closed. It's clear that the intake assembly had been removed previously.

 

[F_R]

Re: Oil drain leaf valve - which way round?!

The thick curved part is the leav valve stop--it limits how far the leaf valve can open. So, obviously, it needs to be installed with the curved ends away from the crankcase so the leaf valve can open from pressure within the case.

Once installed, the leaf valve should be laying flat against the crankcase. If the ends are permanently raised up, something is wrong. They may be bent, have dirt under them, the crankcase face is not flat, or something else. You will have to make a close examination.

 

[Swell]

Re: Oil drain leaf valve - which way round?!

Many thanks - that explains it perfectly, though what does the quoted 0.04" clearance relate to?

Is it there so that excess oil sitting at the base of the crankcase is forced out on the exhaust stroke? What happens to the oil? Does it re-enter the crankcase via the intake?

 

[tashasdaddy]

Re: Oil drain leaf valve - which way round?!

it lubricates the crankcase. there is no oil sump in 2 strokes, all fuel and oil enter thru the carbs/leaf valves.

 

[Swell]

Re: Oil drain leaf valve - which way round?!

I was wondering though if this valve is to deal with any oil build up at the base of the crankcase?

Any ideas what the quoted 0.04" clearance relates to on the valve?

 

[F_R]

Re: Oil drain leaf valve - which way round?!

I don't have the manual in front of me, and in all reality probably have never actually measured one. After all, what is going to change the distance unless somebody has been dinking with it? However, I believe it is the distance from the crankcase to the raised tip of the leaf stop.

The whole purpose of the drain valves is to drain off fuel that has "rained" out of the fuel/air charge as it passes through the crankcase. If not drained off, it puddles up and results in extremely rich mixture passing through the cylinders as you speed up from idle.

Where does it go, once it is drained off??? Do you really want to know? It goes into the exhaust housing and on out into the lake. Hey, that's the way they did it for many years. Note, the lakes survived too.

Nowadays, we are "green" and the drain oil is pumped into the cylinders for burning (if it even HAS drain valves). So the oil is burned instead of going into the lake. Yeah, right. Believe that and I have a bridge to sell. Check out all the threads here, asking what is that black goo running out of my motor.

In all fairness, the crankcases on modern motors are better designed and produce less "rain" to begin with. And in many cases use half the oil to begin with.

 

[Swell]

Re: Oil drain leaf valve - which way round?!

Thanks for that very comprehensive answer. That does explain why there's oil floating on the surface of the water in my wheelie bin test tank! I was actually worried that it might have been fuel leaking from somewhere e.g. via the fuel pump, but now I know that it's that valve.

I did winder if there should have been a gap between leaf and block, but if that gap was 0.04" that equates to no valve, so that's resolved!

Many thanks!