From PAW model dieselengine factory: NEVER dismantle an engine in order to "decarbonise" it. Excess carbon is ejected by the engine automatically as it accumulates.

I has used motoroil, castoroil and never experienced the engine has been damaged by carbon.

Mostly of carbon came from burned kerosene/autodiesel and a very little part from lube oil. You can see there are much oil out of exhaustport/muffler because the engine are running colder than glowplug engine.

Jens,

I do not have a PAW engine but I must clean my OS .40 max after about 5 hours of operation because the performance suffers when the carbon collects. But, this engine gets heavy use and has never had any sign of wear.

I did recently damage the piston pin bearing of the connecting rod in my Enya .25 because I did not remove the carbon soon enough. It collected and hardened on the exhaust port side on the piston and head. The engine operated well so I did not know about the lack of clearance at this location. At some point I adjusted the compression inwards--the engine wasn't overcompressed but the piston lacked clearance at just one point in the combustion chamber. So now I have to replace the rod or learn how to make a new bearing.

I also doubt that the oil was the single cause. The kerosene I have been using is intended for heating and may not be as pure as other sources. Some mineral oils I have used actually seem to clean the engine as it runs. I wonder if the larger engines are more likely to build up carbon? My .061 Norvel conversion diesel does not seem to get a build up of carbon. Maybe it spits it out as you describe for the PAW.

I think your original advice was good and I plan to continue to use substitutes for castor oil. I am hoping to have a cleaner engine if I use the modified olive oil and diesel mineral oil mixture.

George

Wrong adjusted mix/comression can give more carbon due bad combustion. Adjust a bit more leaner and readjust compression until you can see there are less smoke and smooth running. You can replace with lampoil who are smokeless and give less carbon build up.

I will give you the copy of by book how to operate the diesel engine here..


Edit: Resized the pictures to improve readable text.

Jens,

Thank you for taking the time to copy the book pages for me. Because of the time difference between us I was able to read them before going to the field today. I did not find anything in the pages that was in conflict with my practice, but I have gotten into a habit of just starting and flying, and haven't touched the compression setting in a long time. So it was good to have a reminder to take time and check settings and performance.

My OS .40 conversion starts very easily. I turn out the needle 1/2 turn, choke the carb for one turn of the prop and then apply the starter. The engine usually starts immediately as it did today. I let it warm up until the engine note is smooth and then I turn in the needle for best running and then back a little to account for the prop unloading in the air. The compression is, I think, just about perfect. If I lean out too much I begin to get that crackling note in the exhaust. Turning in the compression makes the exhaust sound go flat and the engine speed begin to drop. If I reduce compression from its current setting, the engine does not throttle as well (it is normally very responsive and does not load up when going from low speed to high speed). Flight performance at my settings is very good. The plane is relatively heavy and sized for a larger engine...yet I get short take-off distance and impressive vertical performance. The needle valve setting today was 1 1/4 turns out, running on muffler pressure. Fuel economy is very good, and, there is no smoke other than a faint white fog at full throttle. Immediately after a run, the muffler is cool enough that I can touch it briefly without burning my fingers.

Your comments have made me think about my mix. I have been running about 23% oil (50 wt automotive). I am wondering if more oil would help to keep things clean. I notice that Slope-soarer's mix has heavy oil and yet his engines seem to run quite well. I was inclined to think the oil might be a problem. . .but your comments make me wonder if I simply don't have enough of it. Since I am running fairly high ether (over 30%) I can try to reduce it down to 15% and increase the oil. That way I won't have to give up any of the energy from the kerosene. I could use my current mix as a venturi prime, since the engine seems to start so well on it.

Thanks for your comments.

George

George,
If you reduced your ether to 25% and added 5% Olive oil I would say starting/ handling would stay the same but you would get less carbon buildup, then keeping 28% Total oil you could alter the ratio of motor oil to olive to get a clean running motor, the next step would be to try reduceing ether content and uping the kero , but from my readings and experiance little is to be gained with more than 60% kero in the fuel- most team race mixes max the kero about 55-60% and these guys are after both speed and fuel ecconomy.
My personal receipe is 10% castor,12% olive,20% ether and the remaining 58% kero.
Stewart

Stewart,
with this recipe you won the No 9 in fuels recipes in the fuel thread!
I guess it is a very good balance between ingredients, with a simplicity of starting and running affordable to everyone. Throttling should be superior to straight castor.
I think it is better that you, if you want, fill the form there reporting also some interesting additional data, as engines, etc, and comments
I am curious about your present olive oil. Have you tested the straight one? Mine works exactly as the double modified one!
I am presently collecting a wide range of data from literature, and nextly you will see some first interesting viscosity diagrams that support the choose of mixing olive and castor.
Ugo

Stewart,
your fuel is not No 9, but it is 10, since the preceeding one from Pe is yet unnumbered, but is No 9.
ugo

Stewart,

Thanks for the suggestions. A few questions: what size engines are you running? My big engines (6.5cc, 4 cc) seem to react differently to a given mix than my small ones (1cc). The small ones are converted Norvels & mine seem to behave as Andy W. has described his: lots of ether to start. Does your 58% kerosene mix require anything special (high ether prime, for example) to run in your engines?

I still have not modified my olive oil yet as flying weather has been perfect & I have over a liter of fuel left. It's supposed to rain tomorrow, so I should get to it then.

George

Geoge,
The mix gives similar starting (maybe slightly easier ) to std old english mix, ie 1/3 ether,1/3 kero, 1/3 castor, but delivers better power, I must admit not useing it in any R/C engines so throttling is not known, but due to the easy starting I cant see a problem , (slope sourer has reported better throttling with olive castor mixed lube on lower ether fuel)
I have run my mix in McCoy 049, Cox 049 reedy conversion, Barbini 1cc, Paw 09, Mk17 09, Paw 19, all hand start easy with no need for high ether prime, exhaust is almost clear in colour, compression is similar to old english -maybe backed off slightly , needle is a bit leener.
Stewart

Hi Stewart,
First.... thanks for getting me started on using olive oil, it has been a great success.

George,
I made different fuel mixes using 10% ether. They had about 8% castor oil included.

Mix No1 had modified olive oil at about 25% added
Mix No2 had a car diesel engine semi synthetic oil added at about 25%

Both mixes had about 2% of ignition improver added (it's actually sold for use in diesel cars and trucks)

Both mixes ran well but needed a couple of primes of normal commercial fuel down the venturi and then a spin with my starter motor.

The mix with olive oil, as the main part of the lubricant, would allow the engine to idle very slowly and extremely steadily. I left it idling for 4 minutes at a time. It would accelerate O.K but there was a bit of hesitation.

The mix with car oil, as the main part of the lubricant, would idle O.K, not quite as slowly and steadily as the other mix though. The throttle could be thrust open, by hand, and the response was both instant and smooth.

Then I had an idea (that's rare ! ) I mixed both fuels so I had 50% of each. This mix when tried not only gave the very slow idle but would respond instantly and smoothly to thrusting the throttle open. This series of tests took up 2 hours on the day I did it. I repeated each run with a particular fuel at least 3 times in order to check that results were consistent.

I believe you also intend to use diesel with gliders. I find that my engines work hard to get my 100" gliders aloft and then will be at idle for long periods, especially if there is decent thermal activity.
I have found no throttling problems when using my fuel mix in this way. Once the good thermal passes and the heavy sink appears it is nice to have the engine wake up when required

For priming I just put 2 small drops in the venturi. You may need to do this a couple of times before the engine will ignite the low ether content fuel. Fuel with no ether at all can also be started in this way but will take, maybe 3 or 4 primes before there is enough heat to ignite the fuel.

To start with I would be inclined to use either 20% ether, like Stewart does, or use at least 15% ether. This makes for easier starting. A mix of castor oil and modified olive oil will probably do the job for you. The castor gives some margin of safety and the olive oil should keep things easier to clean.

The other thing I do.... my engines are on "power pods" which are held on by rubber bands. I fit an exhaust deflector (as used for glow engine) and then stick a length of brass (or aluminium) pipe into the exhaust deflector. The other end of the brass tube is pointed down below the fuselage and is held in place by one of the rubber bands. This makes the exhaust quieter and also deflects most of it away from the glider, alternatively you could run a tube right to the back end and keep the glider even cleaner ! The diesel engine is not as sensitive to back pressure as the glow engine.

Modifying olive oil: my experience and a few questions--

I mixed 15ml water, 20 ml dishwashing detergent (Palmolive brand) and 10ml glycerine. I added 500 ml extra virgin olive oil and heated while stirring until it began to foam. Question: this stuff foamed like crazy. I had to remove the pot from the burner for a bit to regain control. Someone mentioned that clothes washing detergent or a spray cleaner like "409" brand would reduce the amount of foam--Did anyone actually try this alternative?

I resumed cooking and continued until the foaming stopped. I then had a brownish-clear oil with a dark-brown separation on the bottom. I poured off the oil into a plastic bottle and let it sit to complete separation. Due to the brown tint to the oil, I decided to "wash" it. I poured off the oil, added 25% water to it and agitated it. This formed an opaque creamy yellow solution (an emulsion?). I let it sit overnight and a semi-clear water layer formed on the bottom but the appearance of the top layer did not change. I decanted and then repeated the 25% water wash. Again, an overnight sit produced a separation but no change in creamy yellow appearance of the upper layer.

Finally, I decanted and then gently heated the oil. I discovered that "gently" was the only method, otherwise superheated water from beneath the oil exploded upwards, spraying oil all over the place. By stirring constantly and maintaining just enough heat to drive off the water I ended up with a pleasant amber colored oil, much like the original oil in appearance. No further separation was detected.

How does my experience compare with those of you who have actually attempted to modify olive oil?

If the rain ever stops, I'll report on my mixes and testing.

George

Hi George,
I use washing up liquid (the term used for the liquid used here in the U.K when washing dishes by hand, as opposed to putting them in a dishwasher). The brand I use is Fairy... but I don't suppose it matters. I originally used green couloured Fairy liquid but this seemed to throw a noticeable amount of green deposit. I have changed to a lemon coloured version and this doesn't show the same effect.

I find that the mix produces a lot of foam when it comes to the boil and the heat has to be reduced very quickly in order to control it. A pan big enough to prevent the oil foaming out is also advisable. I leave the heat at a level where the contents will stay in the pan and gently stir, stirring should be done right from the start when first heating the mix and continued throughout.

Once the foam subsides and there is not much being produced I turn the heat down to give a low simmer and let it simmer away until the foam dissapears. Leave it to cool and then put in a glass container - usually the empty olive oil bottle !

I also find that there is a brown deposit on the bottom of the pan and I leave this behind when pouring out the cooled oil.

I have had mixes of modified olive oil which were a bit cloudy, they worked fine and after being left for quite some time they did clear.

I have never tried washing it or using anything but the washing up liquid I mentioned. I think you will find that your modified olive oil will work O.K.

I think the only drawback to olive oil is the fact that it degrades reasonably quickly. A batch of 500ml will make several fuel mixes so it is not worth making large quantities at once. I would hope to use any olive oil I modify within a year of making it.I am using some that I made about September last year.

If the rain and wind ease up I will get some more flying in as well...

Reg

When i heated up the olive oil until the foam came, leaved the oil in constant heat (Kitchen oven are electric) and simmed away until the foam dissapeared. Then i heated up a bit more, the foam came again, but less than before, simmed still away until the foam dissapeared and heated up more again, the foam was not there longer and the smoke came from oil. Also the oil got increased boiling point than natural olive oil. It is important the oil must not burn in the diesel engine in case lube will be disappeared in cylinder. I ran the engine, there was enough oil out of exhaustport as a sign the oil was not burned away in the engine. See my engine: http://www.youtube.com/watch?v=wmH6WUMUEJg

Worth to know about biodiesel here: http://journeytoforever.org/biodiesel_yield.html , http://journeytoforever.org/biodiesel_yield2.html , http://journeytoforever.org/biodiesel_bubblewash.html

Can one of you explain difference between the modified and unmodified olive oil. What is the draw back of running unmodified olive oil?

I just got some biodiesel to try.. It definetly feels more oily than diesel. I can't really use the crank case drainings with the biodisel - kind of defeats the purpose don't you think!? There is a biodiesel station near by now and I can get all I want...

I saw the oil ended to cooking more after the oil was skimmed, then i increased temperature each time the oil was skimmed until the oil got near boiling temperature before i stopped and let it cool down and added in the bottle.

My observation are also: increased boiling point. Difficult to feel and see viscosity are increased in compared with castor oil, more like as thinn motoroil. I has not equipment to measure viscosity.

Not tried to run the engine with unmodificed olive oil.

Results of testing:

I mixed up some fuel using my new modified olive oil today and did some static testing. I basically just modified Stewart's brew a bit: 20%ether, 11% 10w-40 diesel engine lube, 11% modified olive oil, 2% octyl nitrate (Amsoil) and 56% kerosene (actually a little less, since I counted the hexane in the JD starting fluid I used as part of the kero). The diesel engine lube was Shell Rotella and I noticed it mixed instantly with the kero.

I also mixed up Andy W's 40/40/20 to use as primer if needed, using modified olive oil for the 20% lube.

First, I tried my Norvel 1cc conversion. It loved the 40/40/20 as a prime but it took some playing around to get the 20% ether brew to catch. When it did, the engine ran strongly at nearly 10K rpm on a 7X3 inch prop. However, compression setting and needle setting were touchy. Throttling was poor. After about a minute or so of running the engine would sag and die. . .no fiddling with compression or needle had any effect. The engine was very hot and wouldn't restart. The engine has a pretty good "pinch" at TDC but this was gone and the resistance to being turned was much less. As soon as the engine cooled, the pinch returned and it could be restarted--but always with the same result. I pulled the head to check things out and found an adequate amount of oil and no evidence of seizing or distress. The piston and head were very clean and there was no evidence of oil burning.

I was disappointed by the Norvel but tried the same new mix in my .40 OS FP conversion. I didn't change any settings from my old mix or use any prime, aside from pulling fuel from the tank by choking the carb for one turn of the prop before applying the starter. To my surprise, the engine fired right off as usual. A touch-up on the needle valve and I was rewarded with noticeably higher rpm and much more thrust than I usually get from this engine. It throttled quite well and idled without a problem. While the engine ran warmer than usual, it wasn't as hot as if it had run on glow fuel. I didn't hear any clattering or signs of overcompression. In fact, the engine seemed to run quite smoothly. I pulled the head afterwards and found adequate oil and evidence that the new blend was actually cleaning up some of the old carbon deposit. I'm dying to try this one out in the air as I am hoping to get a performance increase.

My guess would be that my Norvel needs more oil to help dissipate the heat and retain a good compression seal while running. . .something that I now think that Reg's high oil brew does in his small engines. Unless my OS .40 (6.5cc) shows some sign of distress, I think I'll run a few tanks worth of this new blend through it. If all else fails, I now know the Norvel loves 40/40/20--but I'll try Reg's approach first.

George,
Novels are a diesel unto themselves, there fuel requirements are a bit fussy, some will run ok on low ether fuels but most? wont and need the 40+ ether , I would run 25% oil at least a 50/50 castor olive should be ok. As you say they lose performance if run hot due to the high expansion of the alloy cylinder- the piston is low expansion high silicone / nickle plated. Andy W reported around 12,000RPM on a cox 8x4 from memory.
Stewart

My friend brought a norvel conversion over here and we "ran" it but it didn't run great and that was with Davis 1/2 a fuel not my low either BBB. The PAW .061 runs way better. I get 13,800 to 14k on a MAS 7x3 and it will run on my nasty BBB although it starts better with higher either.

If you want to keep carbon down try running straight 30 or 40wt motor oil. If you look at the specifications buy ones with the lowest ash content.

That's Odd. The Norvel .074 I did runs very well in my opinion. Some info [link=http://dieselrc.com/blog/]HERE[/link].

JD ether has no hexane, at least the MSDS that I have says there isn't any.

Smaller diesels in general like more ether. A few of the very small engines (0.1CC) won't run on any less than 40%.

Mavi, where do you fly?

Thanks to all for your responses on the Norvel. Now I know I'm not alone with this apparently fussy engine. I've heard good reports about the .074 diesel Norvels, but not as much about the .061. If increasing the oil doesn't do the trick then I guess I'll try the 40/40/20 mix since my engine seems to like it so much. Admittedly, my .061 is a bit of an oddball. It is a UC converted to RC with an AP carb. It runs like a banshee on glow.

Greg--I just assumed the non-ether 20% in JD starting fluid was hexane as other fluids seem to use it. Whatever it is, I just counted it against the kerosene. I have a question for you about lanova cells that is off-topic for this thread. I'll send a PM.

George

Testing in the air:

Today I flew my OS .40 fp on the fuel I mixed and static tested on 15 August. While the weather was cool and damp, starting and smooth running was as experienced while static testing. The power boost over my old high ether mix was apparent. Based on vertical performance, I'd say that I had at least a 10-15% increase in thrust (12 X 6 prop). This is a plain bearing engine that I purchased on eBay for $23.00. It is well-used; the pinch at TDC is long gone. I spent 25 to 30 minutes total time in the air with no difficulties at all. At the end of the day, I let it idle for 5 minutes or so while I picked up my gear. Then I went back and hit full throttle. It jumped up to peak rpm with only the slightest hesitation.

I pulled the head when I returned home. There was a very small amount of crud present, but it was very soft and soaked with oil--I could wipe it up with a rag. I suspect it collected while idling and looked likely to be blown out at normal flying speeds.

So here's my larger size engine vote for Stewart's brew using 11% 10w-40 diesel engine oil plus 11% modified olive oil for the lube.

Sorry friends to be late.. i readed some pages, and i will read the rest later.. But, if i understood correct, the major factor of Ether is to help in first start and keep the engine colder.

Then, if i apply some high cetane fuel in the carb during the first start and use a high rpm eletronic starter, then, can i run 80% diesel and 20% oil?

Does somebody tried thinner to mix in diesel? Maybe it have high cetane number.. i would like to try it.. Here is very difiuclt to buy Ether too, and im looking for to a substitute for it.



Thanks,



Matheus

Matheus,

Yes, your thinking was the same as mine and I did try several other volatiles and they did NOT work well. It appears that SOME ether is required, at least if you want to have good throttling. If not, then any diesel engine can be made to run without ether. Starting is the problem and that is solved either by applying heat directly to the engine with a heat gun, or using a high ether prime to get a few prime runs that warm up the engine sufficiently. At the field, careful application of a small torch would work.

Thank you very much for your fast reply, Andy..

Im from Brazil, south america, and here in winter don´t go lower than 12 celsius degrees, and in summer usually beats more than 30 celsius degrees.. Maybe, here will be more easier to start without ether, no? Or is a lot of hotting required to first start without ether?

And after hot, you take off.. then, when you need turn on the engine again, will be easy to start without ether? And about diesel cetane boosters, does it work or not?

What is your suggestion of diesel fuel mix to me, that want begin without Ether? Can i have some of other type of starting fluid that don´t have ether inside?

Did you try thinner?


Cheers and thank you again! And sorry if some of my doubts are in past pages.. [&o]



Matheus

Hi Matheus,

Yes, I tried thinner as well as acetone. I also used WD40 in place of the kerosene and the engine ran well. I don't recall if I used ether or not in the WD40 mix.

By your description of the weather in Brazil, I see that even in cans, ether is not common. Unfortunately, there really IS no substitute for ether. But any engine can be run without it, as in just getting the engine up to temperature along with some overcompression.

I've run 78% kerosene, 20% oil and 2% cetane booster with good results. BUT the fuel mix will depend on the engine. Early, traditional, steel/iron engines should have up to 30% oil. If you have a modern type, ABC engine, then 20% will be fine.

Cetane boosters DO work and it's my understanding that they really don't boost the cetane but act as ignition improvers, somehow.

That is correct, heating up the engine is the key item in getting an engine to start without ether. But after a flight, the engine will cool to normal temps and you must get it hot again. So yes, if your air is hot already that will help but your engine will need to be much hotter than that. I would guess that the engine gets hotter than 100 Celsius.

Right now, I'm in the big city, some 450 miles away from home. I have my computer with me and two small planes. Otherwise, I would go right out and run some engines to see what kind of formula you might have luck working with. But meanwhile, let me know what engine you are doing diesel with and I'll try and help.