Oil valve solution to oil falling to crankcase

Status
Not open for further replies.
robs ss said:
Shane
As you suggested, I think it's more important to see what's in the line below the valve - at least from a trial point of view.
Click to expand...
I read from the product maker "just posted" 3or4 pounds suction to lift the ball from its seat.....from memory a oil sender needs roughly 7 psi to put a light out ....yes a clear line is the go i think mate 👍
 
An automatic valve only has to hold back 2ft height of oil to be on the safe side so the ball is pressed onto the seat, ie from the oil pump to the top of the oil level in the tank. So when I was modifying an air line non return valve to act as an auto valve I had a 3ft pipe and filled it with oil to 2ft and checked for oil coming out of the valve. I slowly reduced the length of the spring until it just leaked.

2ft height of water produces a pressure of 0.85 psi so an auto valve not opening until 3 psi is set too high.
 
kommando said:
An automatic valve only has to hold back 2ft height of oil to be on the safe side so the ball is pressed onto the seat, ie from the oil pump to the top of the oil level in the tank. So when I was modifying an air line non return valve to act as an auto valve I had a 3ft pipe and filled it with oil to 2ft and checked for oil coming out of the valve. I slowly reduced the length of the spring until it just leaked.

2ft height of water produces a pressure of 0.85 psi so an auto valve not opening until 3 psi is set too high.
Click to expand...
That could be the logic behind the hNw valve. It screws into the oil tank, so has what, 3-4 inches head of oil acting on it? In that case it can’t presumably get away with an incredibly light spring.
 
This discussion is probably one that Velocette engineers had over 60 years ago. Get the valve as high as possible and reduce the required spring pressure.
I have an hNw valve coming and will test for opening pressure and % reduction in full flow. Experiental design still not finalised.

I still have to examine why the AMR mods are not working as anticipated. It may well be that the outlet spigot is Mk3 and too long - but while I have the timing cover off I will also lap the new pump to ensure clearances are good. Maybe "new" pumps aren't as "new" as anticipated?
I have not done it yet as it isn't a small job and the bike is rideable as is.
Cheers
 
Last edited:
The height of the valve in the installation makes no difference if the oil line is fully primed, the oil is still 2 ft high and acts above the valve and below the valve. The oil sucks at the ball when below it. Its the spring applied pressure being greater than the 2ft pressure that is important plus being only enough.

What really surprised me was how little air pressure was needed to open the valve just blowing through it by mouth, barely a light puff was needed.

What was also better was the seat was rubber not steel, the previous valve I had used leaked all the time and was steel ball on steel seat. When I cleaned it out there was the barest spec of dirt on the seat. So equivalant to the issues you get with Triump oil plunger pumps and grit on the valve seat.
 
kommando said:
The height of the valve in the installation makes no difference if the oil line is fully primed, the oil is still 2 ft high and acts above the valve and below the valve. The oil sucks at the ball when below it. Its the spring applied pressure being greater than the 2ft pressure that is important plus being only enough.

What really surprised me was how little air pressure was needed to open the valve just blowing through it by mouth, barely a light puff was needed.

What was also better was the seat was rubber not steel, the previous valve I had used leaked all the time and was steel ball on steel seat. When I cleaned it out there was the barest spec of dirt on the seat. So equivalant to the issues you get with Triump oil plunger pumps and grit on the valve seat.
Click to expand...
I think you are wrong there. If the valve is only 3" under the oil tank level the spring has to resist a third of the pressure of a valve that is 9" below tank level.
Basic physics.
 
Yes the valve is higher but the oil below it still acts on the valve as gravity applies both on the oil above and below the valve. The oil below the valve still wants to move downwards towards the pump and unless air leaks in will apply this as suction on the ball.
 
kommando said:
Yes the valve is higher but the oil below it still acts on the valve as gravity applies both on the oil above and below the valve. The oil below the valve still wants to move downwards towards the pump and unless air leaks in will apply this as suction on the ball.
Click to expand...
Yeah, I hadn’t thought about that, but I think you’re right.
 
Just try this experiment to confirm (I already know the answer from filling up the central heating oil tank up a slope from a lower reservoir where the pump needed help by priming the pipe).

Place an open topped full water container at the bottom of a wall with a ladder next to it. Put a long hose into the container and let it fill with water, put a brick on one hose end to stop it rising and and a finger over the other pipe end.

Now keeping the finger on the end of the pipe climb the ladder, if the hose is clear look at your finger and the skin will be pulled into the hose by the weight of the water column in the hose. Release the finger and the water column will drop back into the water container. Look at your finger and it will have a red witness mark where is has been pulled into the end of the hose.
 
Last edited:
kommando said:
Yes the valve is higher but the oil below it still acts on the valve as gravity applies both on the oil above and below the valve. The oil below the valve still wants to move downwards towards the pump and unless air leaks in will apply this as suction on the ball.
Click to expand...

It may be irrational, or maybe not, I think I prefer not to add a potential obstruction in the oil line.
 
Mart UK said:
It may be irrational, or maybe not, I think I prefer not to add a potential obstruction in the oil line.
Click to expand...
My Mk111 has a nice aluminum weld up scar on the T.S. upper crankcase where the T.S. rod smacked it open .
Guess what caused this ? ( and other damages ... ) .
 
I look forward to what the issue is with Robs AMR modification to the timing cover...or pump
 
Last edited:
kommando said:
Yes the valve is higher but the oil below it still acts on the valve as gravity applies both on the oil above and below the valve. The oil below the valve still wants to move downwards towards the pump and unless air leaks in will apply this as suction on the ball.
Click to expand...
I stand corrected - good thinking!
 
This may have been asked by now up-thread but why doesn't my MKIII anti-drain valve work? Years ago I lapped it to the case and put in a new spring but it sometimes works but usually not. Does anyone have a MKIII whose valve unfailingly works? My former boss at the MC shop said it was pointless to mess with it but I did anyway. As usual he was right. What do/did we not know in 1990?
 
Status
Not open for further replies.

Similar threads

texasSlick
How to Make the Atlas/Dominator Primary Oil Tight
2
Replies
20
Views
10,221
norton bob
norton bob
Back
Top