Flypast111

I am a “u-control line” model enthusiast and an owner of two (2) PAW TBR diesel engines, 0.19 & 0.40. I have successfully broken-in, or run-in, the 19 TBR, but I am having some difficulty with the 40 TBR engine. I have successfully run the following engine RUN-IN operations without using an electric starter;

19 TBR Engine:
a. ten (10) 2-oz. tanks of self-made diesel fuel through the 19 TBR without any major issue's
b. self-made diesel fuel formula: 30% John Deere ether starting fluid (part number RE556468; 80% ether & 20% alcohol), 30% castor/synthetic oil mix, 35% kerosene, 5% cetane boost … seems to work well … OK
c. followed supplied RUN-IN procedure and got good results … yeeaaahhh! … congratulations to PAW!

40 TBR Engine:
d. not so with the 40 TBR engine => in two different days of 3-5 hour duration events, I have only run about five (5) 2-oz. tanks through the 40 TBR engine … I also ran about two (2) short duration … maybe half-oz. … diesel fuel “start-slow run-stop” events as well … no other successful runs
e. in addition, however, I have experienced several low-cyclic motoring/firing resonance “back-&-forth” operation events ... which demonstrates that the engine is attempting to run, but will not “fully operate” per normal high-speed operation …. hhmmmnnnn!
f. also for note: the 40 TBR needle and venturi became “loose” during the initial RUN-IN and had to be tightened … the needle does not always demonstrate “stable” position control during engine firing …. sometimes it rotates +/- 30 degrees during operation … I removed the needle and “squeezed” the split-brass mount to reduce this behavior … it has helped ... but still the needle is not always fully “position-stable” … ???

Does any of this experience indicate to anyone just what is occurring here? Please advise further … I could use some help here to get this non-RC 40 TBR running “up-to” normal operations ... THANKS - Flypast111

greggles47

Hi Mate,

The Back and forth "running" could either be the compression too high, wind the comp screw out a 1/4 turn, Or it may just be that you have flooded the engine. Clear the flood & try again.

The needle wander can be cure by a short length of silicon fuel tubing over the splits reaching to the nut. Replace if it gets too soggy from any diesel fuel that may get on it.

controlliner

Greg, ya beat me to it mate. Flypast, it is probably over compressed as Greggles stated. I have a Russian MARZ 2.5 cc engine that bounces back and forth as well when it is at the over compressed, 1/4 turn out on the compression screw will alleviate that. I find that when my PAW engines are flooded, they do fire but whack the chicken stick with a vicious bite.

qazimoto

My Feedback: (1)

PAW have been making mostly decent running engines now since the mid-1950's I believe. One would hope that by now they could have done something about their "agricultural" venturi and NVA setups. It's not that their engines are that cheap either. They could have bought and fitted proper NVAs from OS, ENYA, or the Eastern European suppliers (like other manufacturers), and everyone would be happy.

Flypast111

Flypast111 here again with information regarding PAW 40TBR engine RUN-IN;

a) After 5+ 2oz engine break-in/run-in events, the engine showed non-functional high rpm operation … back & forth resonance … short-slow-run-stop operation …
b) Acquired an electric starter, backed-out compression T-screw, and attempted starter-powered high rpm operation => heard “metallic pop” sound coming from cylinder … clearly a “stuck/frozen” contra-piston condition …
c) Wandering needle valve repaired as follows => used Sullivan Proflex yellow large fuel tubing (PN-S216) placed over split-brass needle asy. … helps keep “squeeze” on split-brass mount ... seems to work so far ...
d) Refueled with self-made diesel fuel (above) and fired engine … success … ahhh soo good!
e) Engine RUN-IN proceed with two (2) more 2oz runs until … yeeewooow! … during third (3rd) 2oz run (eighth 2oz run since new) the engine rear screw-in backplate “popped” out … engine run up-down-slow rpm to nearly instant stall–stop!
f) Inspection … rear backplate appears to be in good working order except for light metallic roughness in first one-quarter (1/4) turn of machine thread … engine motor case mating thread appears to be in good working order as well …

Question: what is the “required” repair to reassemble engine rear backplate? (no gasket present)

Proposal: clean backplate and engine case thoroughly … use silicone sealant applied to backplate near mating surface seal (near threads) to engine block case … screw rear backplate into engine case with finger tightness plus one-eighth (1/8) to one-quarter (1/4) extra turn … to snug part to engine block case … allow joint silicone sealant to cure overnight … next-day, ready for engine operation again …

So please review the above and advise if this is a “correct” repair or otherwise … Flypast111

Lou Crane

Flypast,
First, a question... You cite the John Deere starting ether as 80% ether and 20% alcohol. Past discussions of JD ether saw no specific name for the "other" 20%, but there IS some form of propellant in the product. I suspect that 'other' 20% on the label is propane, butane or other flammable gas (at our usual temperatures.) It thus serves propellant and an easily flammable portion to aid starting.
Related thought - the JD can is labeled in ounces, apparently describing weight, as measures by volume (in UK/USA units) would cite fluid ounces, and metric would distinguish between grams and cc's...

Glad your formula works well in the other engine! Most diesels prefer well OVER 30% ether in the mix, by volume. Ether is much lighter than water at the same volume. A cubic inch of ether weighs less than 4/5 as much as a cubic inch of water (specific gravity is about 0.7, about 70% of water's.) This works for us, BTW. The 80% cited for the JD would fill about 1.4 rimes as much volume! If the can lists 8 ounces , not fluid ounces, then 80% of the weight - 6.4 ounces - would be over 9 fl oz volume . I presume the 'propellant', the other 20% of the weight, simply gasses off uncaptured.

Suggestion already posted should handle your needs, and I felt a little more understanding of the fuel percentages would also help.

Luck, and success!

Flypast111

Lou - When one examines the John Deere ETHER starting fluid contents, one finds the following chemicals (by wt.): ETHER (80-90%), carbon dioxide (5-10%), B200 base oil (petro-hydrocarbon at .1-10%) along with propane & butane (both gases at room temperature at .1-10%). When one "carefully extracts" the contents from the pressurized 7oz. labeled canister, one acquires very nearly 7oz of liquid fluid. I know by experience ... I have extracted some 3-4 canisters already. Clearly, one "looses" the CO2 & propane/butane gases during the simple liquid contents extraction process ... KEEP AWAY FROM FLAME & HEAT. The result is very cool/cold liquid hydrocarbon composed primarily of ETHER/B200 base oil contents; what I called the 80%ether & 20%alcohol => now read that 80-90%ether & .1-10%B200 base oil. Also, by the way ... ETHER boils at about 95F(~35C). Thus, it must be handled with GREAT CARE (safety first) ... it is gaseous combustible at elevated seasonal temperatures. Again ... KEEP AWAY FROM FLAME & HEAT. And again ... one should perform the canister liquid extraction process only in a well ventilated area to outside air ... due to the presence of propane/butane gases included with the CO2 lost to the atmosphere ... Flypast111

Lou Crane

Flypast111,

Thanks for the details I knew I'd heard quite a while back!

Still, may I ask whether you weighed the 7 ounces of fluid captured, or measured the volume obtained? I DID mention the Specific Gravity difference between technical ether and the standard base: water, which suggests that the 6.4 fluid ounces of ether (actually I should have used the contents weight of 7 avoirdupois ounces instead of 8.) 80% of 7 is 5.6 ounces, and at an SG of 0.7, that weight of ether should yield a volume of 8 fluid ounces. Slight losses in 'capturing' ether from the spray can may be involved here.... or perhaps a random volume of other liquids as the range of possible content suggests is possible.

Again, thinking non-metrically, a quart is ~ .947 liter (volume) so a bit more ether will be needed to bring a liter of blend over 10% to 12% ether. (A liter fits into a quart can, and I use a 1000cc graduate to simplify mixing a batch. Desired percentages then measure directly in cc...)

Flypast111

Lou .... Thanks for the comments ...
ALL of my physical measurements are in approximate fluid OZ based on simple graduated measuring glass.
I am not getting to use any scientific weights & measures equipment here. Also, the engines (19 & 40) appear
to run fine (with the exception of some mechanical issues like frozen contra-piston, pop-off backplate and
wandering needle). I am working to repair these mechanical items now ... I will use the fuel formula above &
will run 40TBR again and verify corrective actions for normal operations ... Flypast111

qazimoto

My Feedback: (1)

I think you mean that a US Quart will fit into a Litre can.

One US Quart = 0.946353 Litres

One Imperial Quart = 1.13652 Litres

If you're concerned about accuracy then it's not a good idea to use a 1000 ml Graduated Cylinder to mix fuel.

Let's say the mix is 20:30:50 known almost universally as "Olly brew".

One procedure is usually to pour (say) 200 ml of oil, then add enough Ether to the 500 ml mark, and then top it up with Kerocene.

I suspect that this is what you're suggesting.

As soon as you pour the Ether in some of the oil will dissolve in it. So you're actually adding more Ether than the recipe requires.

Same with the Kero but probably to a lesser extent.

The accepted routine is this if you're shooting for a 20:30:50 ratio:

Use the Graduated Cylinder to measure each individual component in turn. It's best to measure and pour the Ether or Kero first. Once you're measured pour each into a mixing bottle. If you shake up the latter and pour it back into the Cylinder you'll find you've "lost" about 30 ml. This is normal.

controlliner

200 ml of castor. Is this enough for a bushing engine or is this better for a ball race engine?

controlliner

I tried a mix of 33-33-33 and I find that with 33% ether, my PAW is anemic. I am going to change it to 33 Castor, 30 ether and 36 kero.

qazimoto

My Feedback: (1)

You can get away with 25% Castor for a PB PAW. So the brew would be 25:30:45. Say 1.5-2.0% Amsoil Cetane booster on top of that would work very well. Mostly in our club we rum the 20% Castor brew in both ballbearing and bushing engines with no ill effects.

5% Amsoil seems excessive.

Lou Crane

Gaz,
Thanks for the info! Lemme see if I understand the crucial bit...

Part of ether dissolves into the oil, and likely also into part of the kerosene: the resulting volume is less than it would otherwise be. The fraction of ether dissolves like salt or sugar would in water, into the water without changing the volume? ...until saturation, of course, after which further added volume becomes evident? (Not voicing doubt, just clarifying whether I understand.)

I infer that a high precision weight scale should then show the full weight of the ether added? (And I ain't got one of those, either. )

Interesting! Two thoughts occur:

Do commercial model diesel fuel makers blend %s by weight or by end volume? I know most, if not all, USA glow fuel sellers mix components by volume, and I recall no comments about any volume loss with fractions added to reach end volume. Perhaps the methanol, nitromethane and 'castor/or synthetic/or both' fractions don't inter-dissolve?

Were volume loss as large as you indicate with ether/oil and ether/kerosene, I expect glow fuel buyers would complain of being shorted on the nominal volume of their purchase. Practically ALL fuel here is sold is in translucent, I think the term is HDPE, jugs or bottles - such loss would be quite evident.

Separate thought specifically re: diesel blends. Most 'home-brewer' comments seem to mention frequent starting problems compared to commercial fuels. After suggesting making sure of the quality of the kero and the oil, the usual suggestion is to add more ether, right? What disadvantage would adding ether to reach the co-dissolved end volume have, other than the cost of the ether?

I really appreciate adding this concept to my understanding! Thanks, again.

qazimoto

My Feedback: (1)

What I said was that the Ether dissolves part of the oil. The Ether is a strong solvent, the castor oil is the solute. The Ether may dissolve part of the Kero. It is most noticeable with the Castor. Just about everything dissolves and/or mixes in Ether. Notice that Castor and Kero don't normally mix very well? Add Ether and they do.

I would expect that an accurate "weighing" of the components and the combined mix would show no loss of Mass.

I have not bought pre-mixed diesel fuel since the 1960's. It's simply not available. I mix my own, only in one Litre batches as I need it..

In glow fuel, the Methanol is the Solvent. It is not a strong solvent like Ether. There probably is some slight castor oil volume loss, but I've never noticed it mixing only a Litre at a time.

I'd imagine that commercial fuel mixers would do so in a quite large container. Large volumes are notoriously difficult to accurately measure, while large quantities of liquids can be weighed using large commercial scales. The Density of Ether, Castor and Kero individually are easy to determine. A one time calculation is all that's needed to get the right Masses for the correct Volume proportions. They can then be mixed in a large container and decanted into the HTPE jugs or bottles of the required volume.

I'd suggest that notion that diesel starting problems due to Ether loss in stored fuel is more of an internet meme than a real problem. I'm a long time model diesel user in a modelling culture where diesels are in constant use. Summer temperatures can reach the mid 40's Celsius. People mix and use the fuel in small quantities. It's simply not an issue.

What is the consequence of mixing homebrew diesel fuel in such a way that there's extra Ether. Only that you're not using the proportions suggested by the manufacturer. A brew with a real content of 32% rather than 30% Ether may actually improve starting.

Lou Crane

Gaz, to your #15...

Thanks again for the great info and several clarifications!

I am not a analytical chemist, so I may be a bit confused by a difference between 'dissolves into' and 'dissolves.' Is there a chemical change to some other substance when ether (or nitromethane - another excellent solvent) "dissolves" an oil, or a liquid like our kerosene? If so, what do they change into?

I should have connected a few dots earlier... I've mentioned that I accept that the weight (mass if you prefer) of the propellant in John Deere Starting Ether gasses off at our usual temperatures, leaving the quoted 80% of mass as liquid ether in the standard spray can. Conversion per Specific Gravity numbers increases the volume (cc, not gram, numbers) usefully.

More? Please...

greggles47

Lou,

I think what Quasimodo is saying is that if you mix 200ml of Castor with 300ml of Ether the total does not equal 500ml of mixture. This is a fairly standard mix for ball raced diesels (add 500ml of Kero and you've got Olly Brew).

The fact that some apparently dissolves does not in anyway reduce the effectiveness of this brew. Most competition modellers using TBR Iron/steel motors will use this or a very similar mix. And as far as I know will mix by volume not weight.

I've actually been putting off making up some diesel fuel, but when I do it'll be Olly brew, with 1.4% Amsoil added after the full litre of fuel is mixed. This method is again pretty standard for competition modellers and produces repeatable results with a minimum of pfaffing about and having to do complicated maths. (like what's 100% - 1.4% );-)

Flypast111

Modelers,

Thanks for ALL of your responses. I’ve enjoyed ALL the banter about diesel fuel and the operations of diesel engines. Your insight and experience have helped me a good amount.

I’ve completed the “repairs” to the PAW 40TBR and they have been successful;

a) To “stop” needle wander, I used small lock washers to set the needle “torque-tight” at 1.5-1.75 turns open … and leave it there
b) For the “popped-out” rear backplate … I cleaned and reassembled using silicon sealant at hand “torque-tight” ... 24 hour cure
c) For the diesel fuel … I added some fresh ETHER (~2oz) to my existing “home brew” given above

Once these “repairs” were completed … it was back to the test stand and … YAHHHOOO!
I ran another three (3) 2oz tank runs for a total of 10+ runs and the engine performed well! ... very good!

I now consider this engine to be ready for regular use … the compression T-screw seams to work best set to about three (3) full threads showing from the TOP of the cylinder head … adjustments for operation are usually within +/- one-quarter turn … or so … time to move on to other u-control line flying preparations … thanks again!

greggles47

Flypast,

If you're ever unsure of your diesel fuel %'s here's a method that'll show exactly what your fuel is.

Place 100ml of your current fuel into a measuring beaker and allow to sit open to the air, but not any possible rain or falling impurities. On a warm day it should only need overnight and when you next check, the ether should have evaporated off and the remaining components will have separated.

You will be able to see the kero and oil as separate components and measure their volumes. Giving Xml Kero, Yml Castor, and the part that would make up 100ml will be the missing ether.
From that you can determine if your fuel had lost ether and the necessary adjustment can be made.

This may take longer in colder climates.