Pela 650 - how does it work?

[garvellachs]

I have acquired an old Pela 650 oil extractor pump - the kind with a cylinder not a sphere - with the pump enclosed in the cylindrical tank. I've taken it to bits (it wasn't working) and cleaned it up a bit. I think the various components (valves, piston etc) work again now but I can't work out how the thing is meant to work overall. It will pump air out of the bottom valve, but the air is simply replenished though the top sleeve where the piston rod emerges. Is there meant to be a seal where the piston rod emerges at the top?

Has anyone taken theirs to bits and worked out how it is meant to create low pressure in the tank? Does anyone have an exploded diagram mabe?

NB this is not a Pela 6000 - they are easy!

 

[Spirit of Glenans]

I borrowed a cylindrical one the first time I changed the oil in my present boat (now have a Pela 6000). AFAIR how it worked was that you had to close a valve, then pump out the air, (possibly 25 strokes), then open the valve, whereupon the oil was drawn up the tube.

 

[garvellachs]

Thanks SofG - I think some people add a valve into the suction tube - but not on mine. I think it should create a partial vacuum just by pumping, but I still don't see how the various valves combine to do it. Anybody got one to check for a seal at the top where the rod goes in?

 

[Monique]

http://www.pelaproducts.com/HowToUse1.htm

Try this?

 

[pvb]

Thanks SofG - I think some people add a valve into the suction tube - but not on mine. I think it should create a partial vacuum just by pumping, but I still don't see how the various valves combine to do it. Anybody got one to check for a seal at the top where the rod goes in?

Logically, there ought to be some sort of seal there. Why not phone them and ask? Number on their website.

 

[danielefua]

Logically, there ought to be some sort of seal there. Why not phone them and ask? Number on their website.

I fully agree! Probably an O-ring or a lip-seal is missing on the lid of the big cylinder where the rod passes through. If you take off the lid, extract the handle and look there with a magnifying glass, you'll probably be able to understand yourself what is missing.

Daniel

 

[VicS]

Logically, there ought to be some sort of seal there.

I fully agree! Probably an O-ring or a lip-seal is missing l

Impossible to say for sure without details / parts diagram for the unit but I am sorry I dont agree that it is logical that there should be a seal at that point.


There is one , for example at the top of a Jabsco toilet pump... but thats because the upper chamber pumps the fresh water in. If the pump only pumped the sewage out there would not have to be a seal there !

 

[danielefua]

Impossible to say for sure without details / parts diagram for the unit but I am sorry I dont agree that it is logical that there should be a seal at that point.


There is one , for example at the top of a Jabsco toilet pump... but thats because the upper chamber pumps the fresh water in. If the pump only pumped the sewage out there would not have to be a seal there !

The Pela works in this way:
1) there is a pump inside the large cylinder that makes vacuum (inside the large cylinder itself) by pumping air to the outside.
2) the pump is operated by an extarnal handle with a rod that passes through the upper lid of the cylinder.
3) the vacuum inside the cylinder sucks the oil through a long small tube which is inserted with a sealed cork in a hole of the lid.

If the handle rod is not vacuum tight, the vacuum inside the large cylinder cannot be made and the Pela cannot work. Ergo, there must be a seal around the rod.

Daniel

 

[prv]

Ergo, there must be a seal around the rod.

Not at all. It could just as well be made with a loose-fitting rod, where the hole connects only with the space above the piston, not with the body of the bottle. Imagine the smaller spherical Pelas but with the pump sunk most of the way into the ball. I've no idea if it's actually made that way, but it could be, and that shows that your deduction isn't valid.

EDIT: Here's a very rough sketch:

Pete

 

[pvb]

Aren't we now at the point in this thread where it's time for someone to come along and say that a Pela pump is the wrong thing to use, and that the OP should buy an electric pump from eBay?

 

[Freebee]

looking at the diagram there is a dip tube that is not shown, this tube goes into the sump, clearly if the tube is not dipped in fluid there will be no suction because it just admits air that the pump is trying to exhaust. so place dip the tube in water as a test and see if it will suck it up. I dont think it needs a shaft seal if the two valves work properly

 

[Steve Clayton]

looking at the diagram there is a dip tube that is not shown, this tube goes into the sump, clearly if the tube is not dipped in fluid there will be no suction because it just admits air that the pump is trying to exhaust. so place dip the tube in water as a test and see if it will suck it up. I dont think it needs a shaft seal if the two valves work properly

+1: OP hasn't confirmed that the tube is in a bucket of water. No fluid and all you are doing is sucking air.

Reminds me of a g/f who could suck a golf ball through a metre of garden hose

 

[prv]

looking at the diagram

Which diagram? If you mean my sketch then you're missing the point - I have no idea how a Pela 650 is designed, that was just to refute Daniel's claim that a seal on the pump rod is essential regardless of design.

+1: OP hasn't confirmed that the tube is in a bucket of water. No fluid and all you are doing is sucking air.

And my Pela 6000 will clearly and audibly suck air through its tube when you pump it up, so putting the end in liquid is not necessary to know if the pump's working.

I'm surprised that nobody here is familiar with the insides of this device, but given that seems to be the case, we're all just guessing until someone can find a diagram or the OP posts some pictures of it in bits.

Pete

 

[danielefua]

Which diagram? If you mean my sketch then you're missing the point - I have no idea how a Pela 650 is designed, that was just to refute Daniel's claim that a seal on the pump rod is essential regardless of design.



And my Pela 6000 will clearly and audibly suck air through its tube when you pump it up, so putting the end in liquid is not necessary to know if the pump's working.

I'm surprised that nobody here is familiar with the insides of this device, but given that seems to be the case, we're all just guessing until someone can find a diagram or the OP posts some pictures of it in bits.

Pete

I agree with you if yours is the scheme but I suspect it is different. In my Pela the main suction phase appears to be on the downward stroke (there is also a minor one in the upward stroke), placing the input port to the pump in the highest place possible, a very convenient design, I guess. In this case, I am afraid, the handle shaft must be sealed. In fact looking at my Pela, it seems that the upper pump side is like the enclosed ugly drawing. In this case not only one, but two seals are needed.
...but I agree these are mere speculations, someone should start unmounting his/her Pela and write sensible things...
If REALLY needed I could do it since my Pela is presently just two rooms away... but, wouldn't it be more convenient to call the guys at Pela?

Daniel

 

[garvellachs]

Sorry about the delay in getting back on this but we have been in NZ for the winter and missed the later answers. The answer is yes, it does need a seal at the top where the rod goes in and out; I measured up (10 x 18 x 5.5) and bought one - the old one was so knackered that it wasn't immediately obvious that it was once a seal even when I had levered it out (it's held in by a nylon ring). Anyway it now creates a vacuum nicely thank you.

There's a non-return valve in the flexible inlet pipe that seems to be the wrong way round - just got to puzzle that out now. Thanks for the imaginative replies.

 

[eddystone]

I have acquired an old Pela 650 oil extractor pump - the kind with a cylinder not a sphere - with the pump enclosed in the cylindrical tank. I've taken it to bits (it wasn't working) and cleaned it up a bit. I think the various components (valves, piston etc) work again now but I can't work out how the thing is meant to work overall. It will pump air out of the bottom valve, but the air is simply replenished though the top sleeve where the piston rod emerges. Is there meant to be a seal where the piston rod emerges at the top?

Has anyone taken theirs to bits and worked out how it is meant to create low pressure in the tank? Does anyone have an exploded diagram mabe?

NB this is not a Pela 6000 - they are easy!

Pela 6000 easy? Time to extract all oil from VP 2002 sump 4 hours; time to (not) drain Land Rover Discovery TDV6 sump - not measurable except in light years.

 

[danielefua]

Pela 6000 easy? Time to extract all oil from VP 2002 sump 4 hours; time to (not) drain Land Rover Discovery TDV6 sump - not measurable except in light years.

4 hours is way too long! Time to extract all oil from a Perkins 4.108 sump: less than 20 minutes, more like 10. Let the engine run for 5 minutes before acting the pump, warm oil is less viscous.

Daniel

 

[CLB]

I agree that it's far too long. Oil must have been cold. I extracted 12.5 litres out of a volvo D4 last week in about 5 minutes. I ran the engine up to about 70 degrees before starting though.