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Oil recovery system


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One of our customers is field testing an oil recovery system in his Jab.

 

The device consists of a small box with an inlet from the crankcase ventilation. The oily engine fumes pass through a mesh of stainless steel and condense. The condensate then drips back into the engine via the oil filler tube.

 

The customer has recently done over 50 hours in a long trip up to the northwest of WA and back to Sydney and reports that his oil useage was negligible.

 

He told me that his unit is a trial one. If it proves effective, the release version will be made from fibreglass. I don't know the manufacturer, but when things progress to commercial release, I'll spread the news.

 

Old Man Emu

 

 

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That's the only place I could think of.

 

But then could just tip it back into the engine manually but doubt that would reduce oil usage cos it is never as much as I need to replace anyway. Not that I ever need that much.

 

I have made emptying my overflow bottle/ catch can easy by installing a metal spout on the bottom with a length of clear hose that then bends up and back into the vent hole at the top of the can. I can now see how much is in the tube = whats in bottle/ when it needs emptying and can drain it without pulling the can out of the bracket.

 

Be interested if there another place that could save a bit of oil on long trips.

 

 

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Sorry. I may have been wrong with the location of the input to the condensor unit. I'm only a storeman/salesman afterall.

 

Obviously there is someplace that you can draw crankcase vapours from, but not being the one who was working on the plane, I didn't take notes. Next time he comes in, I'll make a closer inspection.

 

Despite my failings, the device seems to work, and if anything, it keeps teh engine bay and underbelly oil free.

 

OME

 

 

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I had a think about it overnight.

 

Not sure if my engine (and all the Jabs here) would have a real use for a recovery system as such. My engine dumps out excess newly-put-in oil till it drops back to a constant level - just above the hash marks lower limit on dipstick, and there it stays. No matter how much over the mark I fill, give it a half hour running and all the excess oil has gone into the can. All our engines do the same thing here. I have learned only to fill to the mark now so never have much in the can now but if I do overfill the above scenario happens.

 

So I am now thinking that I would probably actively NOT want a recovery system because it would continually put back the excess the engine wants to get rid of.

 

Jabs are known to have cooling issues when you overfill them so this might actually be a problem rather than a cure.

 

Just a thought.

 

 

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OME , John

 

I have a similar device fitted to my Jab 3300.

 

I don't have to top up oil between 25hr services since fitting this device. You can make them out of different material. I have used Stainless Steel and Aluminium but you could also use fibreglass.

 

It sits on top of the motor so the intake to the separator is right at the breather on the dipstick. The separator is mounted so that it slopes slightly back to the dipstick. Any oil that is separated during flight is then gravity fed back into the motor. I found several people were concerned about water/moisture being trapped in the canister and re entering the motor. I made mine out of Aluminium which allows for the engine heat to stay in the separator longer (heat soak on shut down) eliminating the chance of moisture in the oil. You also must ensure you have your operating oil temp above 85 degrees which will also help reduce moisture in the oil.

 

I don't know how to attach a drawing on this post but if you PM me with your email details i can forward the plans to build one to you. Then you might be able to post it for everyone to see.

 

Cheers

 

Andrew

 

 

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Hi Andrew,

 

Thanks for that. As it happens I am going to be in Bundy tomorrow just after 9 am. My Jab is sitting there waiting to come home. Took it down for the airshow and to have the throughbolts done. Then the weather was bad so left it there.

 

Don't suppose you are going to be near at the airport about that time?

 

Couldn't find how to pm on the this site.

 

John

 

 

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Andy

 

It doesn't impact on the cooling as most of the cooling for these cyliders is done from the air in the duct. There is minimal amount of air that flows over the top of the motor. I have no issues with cyl or head temperatures in my SP6 and i have one of these separators fitted. This picture is from a install to a plane from Europe. My Air Ducts only leave about 5 fins uncovered from the cylinders. All other fins from the cylinders and heads are cooled from the air ducts. You can change the design if you like to make the separator thinner or shorter but you get the general idea of what the concept of the separator is trying to achieve. I have also seen a separator fitted in this location made from PVC pipe with screw on end caps filled with Stainless Steel Wire. It was only about 1 1/2" wide and 5" long fitted to a 2200. There are a lot of different ways you can make one of these to have the same effect. No top up of oil between 25 hr services.

 

Andrew

 

 

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Oops, embarrased to say I forgot about the duct....... The attached photo above has a duct but its in black rather than the plain fiberglass that ours are..... Mind in gear before fingers....

 

I like the idea of the PVC one (assuming its robust over time) It should be lighter I would have thought. How packed in is the stainless steel wool?

 

Andy

 

 

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Andy

 

I haven't tried to make the PVC style but it wouldn't be that hard. Everything can bought from the local hardware store. I just wasn't real keen on the idea of having the stainless steel wire in an area that potentially could over time deteriorate and break off ending up back in your motor. I had 2 make up. 1 in Aluminium & 1 in Stainless Steel. As i said i think the benefit of the metal over the PVC is that it will heat up and retain some of the heat from the motor which will help with the condensation issue. One thing we changed from the design slightly was to have all 5 internal plates attached to a rod running through the centre of the plates. We then welded the plates to the rod and welded the rod to the inside of one of the end caps. This kept them at the set distance and eliminated the need to have all the welds on the outside of the pipe. This just makes the unit look a bit nicer. They polish up quite well on the lathe.

 

I can have one made one up for you if your keen out of Stainless Steel. These are easier to make up for and end up being about the same weight as the aluminium units as the Stainless Steel is a thinner material than the Aluminium. I'm not interested in selling these in big numbers which is why i gave the drawings to John to post on the forum. I did sell one to a bloke in Emerald (Qld) and he is wrapped in it. I gave it to him for what the engineering firm charged me. $130

 

Andrew

 

 

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Hi

 

The oil air separater you have designed will not work. The oil will back up in the separator restricting the air, then creating back pressure through the motor, and before you know it the seals will start leaking oil. I strongly recommend that you spend a few hundred dollars and get a factory made version and have your lame fit it. You will find that the proper air/oil separator have three hoses; two to blow the air straight through and separate the oil and the hose at the base bleeds the air back into the sump when the aircraft is parked. Google oil/air separators do not put the above in. to your motor.

 

King_daniels

 

 

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Can't say I have used one but the design was done in 2005 (note the date on the diagram) and they have apparently been working since then and so far no one has blown an engine with one ( or is admitting to blowing one).

 

I have never seen or heard of a factory made version for a Jabiru. Can you post some details on the factory version?

 

 

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King Daniels

 

I am curious as to why you think the separator won't work. I'm not sure how much oil you think is going to be in this separator at any one time. It is fairly comon for jabiru motors to use around 50ml/hr. Not all of this oil will be pushed out the breather. Some of it will be burnt. So for a 2 hr flight I would not expect to see any more than around 80 mls in the catch can for a motor in good condition. The airflow is by no means restricted. It flows in the bottom entrance and hits the first plate where it then has to flow to the top RH side then hits the second plate and flows to the LH side and so on through the 5 plates. any oil that is separated from the change of direction runs down the plate and when the motor is turned of will run back through the mouse holes at the bottom of each plate and back to the motor. The canistor is at no time restricted. I have had this unit fited for around 80 hrs now and it is working perfectly. I have removed it a few times to check to see how it is working and there is no restriction what so ever. The last 25 hrs i flew i didn't find any oil in the original catch can that is fitted after the separator. I did find a small amout of water in the catch can which i emptied. As John has mentioned the design of this Separator has been around for quite some time and have been used on the Jabiru motors in different countries. I have spoken to people from another forum overseas that have been using them for a few years and they swear by them.

 

Andrew

 

 

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I agree with Jab SP6, this is in addition to the standard separator, and it only has two outlets (and a hole), my near new solid lifter engine appears to be using up to 100ml/hr BUT most ends up in the separator can. This simply reduces the oil I will have to put back in.

 

I know if you dont route the original hose up to highest point then down to catch can oil dump goes up dramatically, this idea is doing the same thing better. Id expect the caught oil will be draining back even when engine operating same as in auto engines

 

Ive seen them made in FRP from the same parts as the original catch units too - this was on a VERY old 4cyl 2200. Some Jab users pour this oil in separator back into engine regularly

 

Id say Jabiru would clearly see this as uneccesary (which it probably is) so they wont spend time on it.

 

 

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Andrew

 

I've had my Jabiru since new, I have done over 920+ hours in it. My first top end overhaul was 470 hrs, I am the only one that flies my Jabiru, the service and the maintenance have alwyas been done by my Lame. As it stands my oil consumption is approxiamtely 150mls per hour, earlier in the peace I made and put an oil separator in and found it worked fantastic, my oil consumption went way down to approx. 50 mls per hour, so after a while, I noticed oil dropping on the front spat and the engine bay was getting wetter with oil. I took it back to my Lame, he first thought that there was a small leak in the oil cooler so he replaced that, there was still oil leaks, I took it back again and the engineer found it was the oil air separator that was causing the problem, so $1700 later after replacing the oil cooler and the engine rubbers and seals and taking out the oil air separator as shown above I have not had any oil leaks but I'm back to using around 150 mls per hour. My 1000hr top overhaul is due soon so with the overhaul I am getting him to put in a certified oil air separator, the lame said that the leaks were caused by oil backing up in the oil air separator, putting back pressure into the motor. So in finishing, that's why I said that I strongly recommend that you spend a few hundred dollars getting an certified oil air separator and getting a proper lame to put it in rather than doing it yourself from a homemade device, research oil air separators on the net to see how they are made, then you will have more understanding of how it works.

 

Regards

 

Daniel

 

 

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King, Can you tell us more about your original design, maybe we can learn from this and alter accordingly. Where was the oil leak coming from?

 

Looking at commercial separators there are a few different types, some almost identical to one we are looking at here, others seem to require gravity drain to sump - ie extra hose run through the exhaust area - not keen on that.

 

I take the point re backpressure but if laid out right it shouldnt be an issue.

 

 

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Daniel

 

This is very interesting info. I used this drawing as i guide only. One thing i have done to improve the breathing of the motor is to increase the size of the pipe to the catch can. The I.D of the standard fitting coming out of the dipstick is 10mm. I removed this fitting and replaced it with a 16mm I.D fitting. I also then increased the size of the fitting into and out of the separator and the catch can so that the overall effect is that i now have a 16mm hole through the entire breather system instead of the 10mm standard size. This has had a dramatic effect reducing pressure in the system. I believe with the increased size (more than double the area) of this system i won't have the problems that you described.

 

Just out of curiosity did you make your separator to this drawing? What is the brand of the unit you plan to fit after your rebuild?

 

Andrew

 

 

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