Dear All,

I see a lot of posts regarding engines that are 10+ years old that seem to be running OK. I have myself seen a few physically that are close to that old. However, over the nearly three years of flying that I have had, I am on my 3rd 55AX in addition to a 75AX and 91FS. The latter two I have hardly use though. Now my question is, did the older engines have a better life than the new ones especially the AX series or are we doing something wrong. Note that we run in the engine by the book, set it a little rich on the high speed needle, use a super filter on the pump clunk, use 20% castor. Most of us on the field have shifted to Klotz-100 this season but we used castor earlier I personally never used nitro until this season. Also, though I have gone through 2 engines, a fellow flier is still using his original 46AX (we starter flying together) which still runs even though it has completely blackened externally. Some of my instructors 46FXs though vintage still run well

Ameyam

Sorry about the empty post and thanks for removing it.
Mis-clicked. Still recovering from a bad flu.

Ameya

By the way, all the engines have been upright. When we tried the 75AX inverted, it wouldnt run reliably and I have only just run in the 91fs.

Before I bought my current 55AX, we tried last year's 55AX at 45Deg from inverted and it kept cutting out

Ameya

How did you go through two AXs??

If you run these things right they will literally last forever. Crashing, sucking dirt, and rust will shorten its life.

I have some engines that have dozens of gallons of fuel through them...and still run great. External blackening is from a leaky exhaust usually...or some backspray out of the venturi. It can and should be cleaned.

I have flown with well used engines twenty five years old that were on tuned pipes and still strong enough to chew up your hand and spit out the bones.

Generally, the more modern engines are even more well made with tighter tolerances. There's no reason why an R/C engine can't last decades when used in typical sport flying applications. What is the nature of your trouble with the two AX engines? have you disassembled them to have a look? The fact that the 75AX didn't run well inverted makes me wonder about your tuning accuracy.

The 1st 55AX seized on the crank pin and sent debris all over. It was running very rich then as I had just cleaned it.
The 2nd 55 AX i opened and cleaned. Actually, I did the same with the 75AX as well. I didnt open the head, instead opened the backplate and glow and kept immersed in clean methanol for two days. On both I noticed rust on the crank towards the counterweight side. It wasnt much and I cleaned as much as possible with a cotton bud. This same engine seems to have "scratches" in the piston side, but they were not much and will disappear when it gets oiled.
The 75AX may have been lost to incomplete break-in but I have not used it since I cleaned it.

No crashes though

Ameya

I've got an old .46 FX that I've been flying for six seasons now, and it was well used when I got it. I have a Magnum XLS .52A two-stroke that I've had for five seasons; it has hundreds of flights on it and it still has a nice, tight pinch and the top of the stroke.

Maybe you're running your engines too rich and your piston liners aren't getting hot enough to expand properly. That would explain any broken connecting rods and/or pins.

Yeah, I agree with that too rich idea.
I've been flying for 3 1/2 years, all of the engines I have bought are still being run with original parts. Except an Aviastar 46 that I have tried every trick in the book to make it run, but the carb on it is useless(anybody know one that will fit?). I really haven't been able to fly as often as many people but this year I am ready. I might find out the durability of the engines I have before summer begins. Some of my engines have been in more than one plane.-BW

Sounds like the OP is mixing his own fuel?? Nothing wrong with FAI fuel but if everyone is having problems then just maybe the fuel blend is wrong?? To date I have never had an engine wear out or seize up but I only run store bought fuel. The nasty crud on the outside of the engine is just burnt oil and doesn't harm anything, just ugly old castor spray. I have some .46FX engines and a Meco that are ages old and still running very well. The new AX line should proove even better? Time will tell. I would give some store bought 10 or 15% blended oil fuel a try and see if you can't perhaps tune your engines a bit better?? Other then wearing out the bearings once in a while there shouldn't be any problems with these little engines.

Run it! Unless there's something wrong with it...don't disassemble it.

Don't worry about the scratches...if it has good compression and smooth bearings...run it!!

What he said...stop taking stuff apart....Rog

Ditto.-BW

Does the area you fly in have sand? Just a thought.

roger

you said you were running it very rich after you put it back together.....dont do this, running an abc/l/n engine to rich will damage it since the liner doesnt expand (not enough heat) causeing a lot of wear

those "rust" stains you talk about are not rust but castor buildup. their is nothing wrong with this just let it be. im running 16% all castor oil and no nitro in my engines (to include a ax55) and it runs well. i dont think its a fuel issue your just running the engine to rich try mixing at a 16% ratio (one gallon of castor for every 5 gallons of methanol, (21.33 oz of oil per gallon per gallon)

Now that you say that I do have to change my statement. I did have 2 Tower Nitro ST15's Stadium Trucks and niether one of them are running now. They lasted less than a year. They ran on the ground in dirt and dust that you just couldn't keep out of the engines. Eventually a combination of needles that turned on there own and would not stay rich and all of the dirt ruined these engines.-BW

There are just too many variables and too many operational procedures that will determine engine life. I just retired an Irvine .36 that has accumulated around 170 hours of actual flight time. That would be the equivalent of 1000 10 minute flights. The primary problem with the engine is the rod bushings are worn out, and it needs bearings. Since the case, muffler and carb are still good, it will remain as a source of spare parts for the other three Irvine .36's in inventory. It's entire life was spent in the nose of a Andrews Trainermaster (an airplane like a Sportster), and that airplane still have a few more flights left in it. It was a kit that I started in 1985, finished in 1995, and is ready to wear out another set of servos and another new engine. Turns out that the servo motors chuck it in at around 150 hours.

I don't have much faith in online discussions of whether and engine is rich or lean. Only because most people that I actually see fly seem to be tone deaf. What they call rich is often pretty lean. They can have ball bearings growling under the engine and prop noise and be totally unaware.

Just answering a few questions here:

1) In my country, aeromodelling is still a nascent hobby. Most people consider it like flying toy planes (which it is, in a way). There are no established brands of models to go around (Just Phoenix) and if you want something specific, you have to import it at atleast thrice the worst local price. Off-the shelf fuels are out of the question and we mix our own. Typically, standard castor mix has 20% non-refined castor (which we filter before hand to remove foreign material) and 80% methanol. Some also add 5~10% nitro and reduce % of methanol. Synthetic fuel only replaces the castor with Klotz. Since methanol tends to hydrolyse, we make only about 5 liters at a time and it lasts me about a month with atleast 3 flights every weekend

2) We tune the high speed needle to max rpm by sound and then richen it by 1/4 turn or so. We also point the thing vertically up and then quickly down to check the engine tuning. We preferably dont touch the low speed needle

3) Didnt take them apart while they were working. Both engines had started giving problems. The 75AX would run for a couple of minutes and then quit. The 55AX was also doing similarly. They were on different planes and in different orientations. Both were using castor. Wonder if that is the issue as many on my fellow fliers who shifted to synthetic are having marked increase in engine reliability. (The new 55AX on the same plane and same orientation works OK). I didnt take off anything other than backplate and glow so all gaskets should be OK.

4) Yes, we fly close to sea but our field isint exactly sandy. It is a polo ground and has plenty of grass

I have taken photos of my 75AX. This is after cleaning with plain methanol and thorough oiling with light machine oil. But I havent yet used the engine since. As you can see, the piston is quite clean and inside too

External gunking I no longer entertain, i clean it of with a old toothbrush and soap water every second weekend. It that time I plug all holes suitably. Ever since we moved to synthetic, gunking problem is gone however.

Ameya

Ameyam

The crank doesnt look that bad I promise, its just the way the photo was taken

Ameyam

Do you mean you have never touched the low speed, or you don't very often? The low speed needle needs attention once in awhile also. This probably isn't your problem but I have had two different engines from two different manufactures that the needles would adjust themselves. one did it every 2 or three flights and the other did it every flight. I fixed those with a small piece of fuel tubing around the needle. Whenever I find any engine running odd I always check both needles before I do anything. If that doesn't help I try different glow plugs. I am sure you already know all of this but I find when I have a particular engine that runs really good for a long time I tend to forget about the basics.-BW

Not even seldom...never. I never did it on any of my 55AXs. After much trial and error on the 75AX, an experienced tuner did some adjustment to its low speed needle. Dont remember what he did as its over a year ago now. It improved the idle but did nothing to stop the engine cutting out at 50% after a couple of minutes or so

Ameya

A recent thread talks about this:[link]http://www.rcuniverse.com/forum/m_9644035/mpage_1/key_/tm.htm[/link]. Even though they are talking about gas I think it pertains even more to glow,check it out.-BW

You have to adjust the low speed needle. When was the last time you inspected your fuel tank and plumbing? Pressure check the tank? (Hold the carb line closed, blow hard into the vent line...pinch....wait 15 seconds....release the vent line and listen for a rush of air as the tank defaltes) Running strong for a couple of minutes then dying sounds a little like a lean condition. Is it really, really hot after it dies? Like...if you spit on the head does it sizzle off?? Cause it shouldn't. Is the clunk attached? Are all the gaskets in place? Is the carb fully seated against the crankcase utilizing the O-ring? Are all the parts on the carb gasketed and tight? Finally..is the carb clean?

And dude....the crank in that photo?? I wouldn't bat an eye!! That thing is fine. I'd be slapping that thing back together and running the hell out of it!! Make sure that your backplate gasket is intact, and that it is completely tight.

Did you run an air filter on those? I run 1/10 scale glows a lot on baseball diamonds and in the dirt and I mean I wail on them!! I kick up major dust and dirt, run right through it..jump it, flip it, you name it...when I pull the filter boot off the venturi is clean as a whistle.

I can imagine with no filter these motors would check out in no time..

Have never used a air filter as I am told that there is loss in performance. Recently I saw a specific review wherein the reviewer used a piece of cotton stocking in top of the carb inlet held in place with a wire tie. Does that help and are there any more suggestions? I dont mind spending a bit if it improved engine life. As for the points that ArcticCatRider raised, checked all of that except pinching lines with engine running as the engine (75AX) was cowled

Ameya

The airfilter is intended for cars and trucks.....you really don't need one on an airplane. It wouldn't hurt but it's certainly not going to remedy your situation.

Take the cowling off so you can work on your engine. You'll need to adjust your low end needle valve, and you'll need to be able to pinch the fuel line while idling to assist in determining this adjustment.

How hot is the engine after it's ran for a few minutes and died? How hard is it to restart?