Evolution 46 problem (general question)
 

I have a Evolution 46 problem, however, I believe my question is of a general nature.

I bought this engine new back in May and have run about 5 gallons of fuel through it. This is my first engine.

As of lately, it has started to act up. There is a rattling noise coming from the engine especially when flying fast at full throttle.
I have had several people at the field take a look at it, but none of the suggestions seem to be the cause of the problem.

Another clue to this is that the engine has always left a black residue on the plane after each flight. Not knowing better, I thought this was normal, but a seasoned guy at the field told me this was not so. It might due this for the first few flights while the engine breaks in, but this has not been my case.

I just took the engine apart and here are my observations:

1. The inside of the back plate is scratched in a circular pattern. Looks like the connecting rod is rubbing against it. This could not possible be normal??
2. There seem to be a lot of play in the crankshaft when the piston is at TDC. i.e. the piston is not moving at all, but I can rotate the propeller ca. 35-40 degrees. Is this normal?

What else should I look for to figure out why the engine is rattling and deposits this black residue after each flight??
Also, I have balanced all my propellers.

Is there anything I can fix?

Thanks for any help.

RE: Evolution 46 problem (general question)
 

A light swirl wear pattern on the backplate is normal, as the rod can slide back on the crank pin during climbs and vertical manuvers.
Check the rear ball bearing for "slop" or "play". The bearing should have no noticeable play in it. I just put new bearings in an Evo that exhibited similar symptoms. Mine had gotten to the point where the bottom of the rod had rubbed the bottom of the inside of the case and that's probably where some of my black exh. oil was comming from.
See if you can wiggle the prop fore and aft while looking at the rear bearing.
Black exh. oil can also sometimes come from the muffler "fretting" against the exh. stack, and that's nothing to worry about really, just check the tightness of the muff. screws. It also might just be comming from the flat aluminum baffle plate inside the muffler. Take the muffler apart and remove the baffle and see if the black oil problem stops.

RE: Evolution 46 problem (general question)
 

"1. The inside of the back plate is scratched in a circular pattern. Looks like the connecting rod is rubbing against it. This could not possible be normal??
2. There seem to be a lot of play in the crankshaft when the piston is at TDC. i.e. the piston is not moving at all, but I can rotate the propeller ca. 35-40 degrees. Is this normal?"


The circular pattern on the backplate IS in fact a sign that either the rod big end, or the crank pin is rubbing. It's sometimes the result of using an electric starter and forcing the crank assembly rearward while starting the motor. This really shouldn't happen in a ball-bearing engine, but it's possible. If there was excessive fore-aft play in the crank itself however, the assembly would be pulled forward in flight and contact with the backplate is then unlikely.

The "play" you note at TDC is a characteristic of any ABC type motor. It's not a sign of a defect, but rather a designed-in tolerance
to allow the crank to keep moving even though the piston actually comes to a complete stop for an instant at TDC while it's travel reverses. The "play" also allows for adequate lubrication of the rod.

Black oil after 5 gallons isn't usually a sign of well-being. Hot, lean running, loose mufflers, or even a off-grade of castor can cause a dark colored, or black oil to emanate from the exhaust. If it's truly a "black" oil...that usually signifies aluminum is grinding someplace. Make sure your muffler and any hardware on it are absolutely tight.

I'm shooting in the dark here a bit however. If the motor has run 5 gals of fuel while exhibiting these issues...it's probably going to keep on running. If this is something that is the result of disassembly of the motor, or a crash or some other undisclosed issue...then all bets are off.

I hope I've been able to clarify at least a few issues....

'Race

RE: Evolution 46 problem (general question)
 

Tycho,


About the rotational 'free-play'; if you can rock the prop over a span of 35 degrees, without the piston moving down from TDC, this would indicate an accumulative clearance of 0.44 mm. if it is 40 degrees this accumulative clearance grows to 0.57 mm.

This is calculated by deducting the cosine of half the number of degrees (since 40 degrees is 20 either way), from 1 and multiplying the result by half the engine's stroke.

It is accumulative since it adds up the clearances of the rod bottom end on the crank-pin, the rod top end on the wrist-pin and the wrist-pin in the piston. If rear bearing slop is also in the issue...
(I know some might say I did not take the rod angularity factor into it, but this is a much smaller number, since the rod is over 3 times longer than half the stroke, so the cosines are much closer to 1.)

This amount of accumulative clearance, when taking into account the 5-6 mm diameters of the shafts involved, is excessive!

I would say 0.1 mm is the maximum you want per location, in a sport engine, or 0.3 mm for all three.
This, calculated back for degrees, would be 14.4 degrees either way, or about 29 degrees total TDC rotational 'free-play'.


Five gallons would be about 16 hours on the engine.
You did not indicate what fuel you are using. This is an ABC, tapered-bore engine and it needs some Castor oil in the fuel; I would say 8% of the fuel as the minimum.

Klotz BeNOL forms less soot than Baker's AA.

RE: Evolution 46 problem (general question)
 

I've been using PowerMaster 10%nitro with 18% Castor oil.

Regarding the muffler, I have had lots of problems with it coming loose. There are two parts to the muffler, and the back part from day one would rotate when running the engine. I tried to tightening the screw that runs through the muffler and add lock-tight, but it didn't fix the problem. The threads became worn. I then bought a new muffler (same one) and that worked for a while, but it too started to become loose and the back part would rotate. I then put a threaded rod through the whole muffler and used two nuts at both ends to tighten it down. This seems to have fixed this problem.

The fact that the muffler keeps vibrating loose seems to indicate excessive vibrations from the engine.

RE: Evolution 46 problem (general question)
 

Tycho,


Please do a search on RCUniverse for engine balancing.

There are several threads about this subject, in which I participated.


The point is a single cylinder engine cannot be balanced (unless you want contra-rotating balance shafts, Etc....).

The aim of balancing in this case is to minimize the vibrations, not to cancel them out.
It is a trade-off between up-and-down and side-to-side vibrations.

When one is zero, the other is maximized and vice-versa.

There is no reason your Evo should vibrate more than the next guy's engine.
Just mount it as solidly as you can.

Using non-nylock locking nuts should solve your problem too and lock-tite only works if there is absolutely no oil, on both the nut and the bolt.
Both must be bone dry, or it will just vibrate loose all over again.

RE: Evolution 46 problem (general question)
 

Mine did the same thing on the .45 Evo trainer engine. I think that your thread locking compound may be your problem. Get the red label Permatex as it is for high heat applications. That cured the .45 problem and my .46NT hasn't started coming loose as I put Permatex red on it after removing the baffle. This is thicker stuff and seems to last much better on engine mount bolts too.

RE: Evolution 46 problem (general question)
 

A common wear point on 2-stroke engines, especially engines run a little lean and hot, is at the wristpin. The small end of the connecting rod and sometimes the piston pin bores will get wallowed out. This is one of many causes of black gunk coming out of your muffler. If I am not mistaken, I think the Evolution engines do not have a bushing in the small end of the connecting rod. Someone please correct me if I'm wrong.

RE: Evolution 46 problem (general question)
 

Tycho,


I wrote the free play your engine has seems excessive.

If your engine does suffer from what Chuck described above, use your warranty and have it replaced/repaired.
Make them cover the shipping too.

That is what the warranty is for.


Next time, break it in as described in [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]this thread[/link].

RE: Evolution 46 problem (general question)
 

Just gonna toss in my experiences...Chuck, the rod does have bushings at both ends. My Alpha engine came out of our club trainer, and didn't always have a balanced prop on it. I replaced the bearings because I couldn't stand the noise any longer. It made clunking noises when you flipped the prop, and when hot it sounded awful! Anyway, even though the rear bearing was total poop, the rod still measured o.k. as far as out of round, or excessive clearance. (but I changed it anyway along w/ the wrist pin while I had it apart because the bottom of the big end had rubbed the inside of the case)
FYI, that sucker turns a 12x4 APC @14,100 w/ a Tower-Aquacraft muffler burning 10% Powermaster (the sleeve mods I did helped a bit too :D )
I think it's a pretty good engine when you get rid of the stock ( cork [:'(] ) muffler.

RE: Evolution 46 problem (general question)
 

So after cleaning and assembling the engine again last night, I just tried it out and I think there are two issues.

1. The black stuff comes from the muffler. Seems like the two muffler halves rubs against each other and this black sooth oozes out from that joint as well. I did remove the muffler baffle inside to eliminate this as a source.

2. When the engine was disassembled I couldn't see any back and forth play in the rear bearing, however, now that I've assembled it again, there seems to be more of a up-down movement of the shaft. Not much, 2/10 of a mm, however there is a clear movement when I grab the propeller and rock it up-down. I can also hear and feel a !QUOT!click!QUOT! when doing this. Does this point toward the front bearing being worn out?

Thanks,

Tycho

RE: Evolution 46 problem (general question)
 

I HAVE A EVO .46 AND MY ENGINE MAKES THE SAME NOISE. HAS MADE THAT NOISE SINCE I BOUGHT IT NEW. I LOOKED AT EVERY THING COULDNT FIND ANYTHING WRONG OR LOOSE OR OUT OF BALANCE. SO I PUT IT BACK IN THE MY PLANE AND I HAVE ABOUT 8 OR 9 GALLONS OF FUEL THROUGH IT NOW STILL MAKES THE NOISE BUT RUNS GREAT. THE MUFFLERS ARE JUNK I AGREE YOU HAVE TO PUT ALLTHREAD THROUGH IT SO YOU CAN GET IT TIGHT . AND BLACK STUFF IS FROM MUFFLER RUBBING TOGEATHER MINE DID THAT ALSO. I TOOK THE BAFFLE OUT OF MINE AND IT IS LIKE A DIFFRENT MOTOR. JUST THOUGHT THIS MIGHT HELP.

RE: Evolution 46 problem (general question)
 

Hi Tycho... Hmmm, 2/10 of a mm is about .008" and while not as much as I had, it's getting loose. You can probably (?) get away with running it for awhile yet. Just how long is anybodys guess though. Is that the crank pin (while trying to rotate the crank) or the whole shaft (counterweight included) moving up and down? "Radial" play is what I'm talking about, in the bearings. The loosness between the balls and the inner/outer races.
I had a 10x7 prop on my Evo before I re-built it, and after running it, while still hot I could move the prop fore and aft probably an 1/8" at the tip, so my bearings (rear especially) were REALLY bad...I however had the attitude that if it blew up I wasn't gonna bum out about it, and just let 'er rip. It got to the point however that I just couldn't stand the noise any longer.
Does the shaft spin smoothly, or is there sort of a "grunchy" feeling/noise when you spin the crank?
I went to a local bearing supplier and got both bearings for $16.50 + tax and did 'em mysef in less than an hour.

RE: Evolution 46 problem (general question)
 

It's the whole shaft moving up-down.

From reading other threds I now know that I have been running the engine hot most of the time, which I'm sure have contributed to this.

Do you have recomendations for another muffler to get? This is my second evolution muffler and I'm very unhappy with it.

The engine still seems to run fine i.e. lots of power etc., but the noise bugs me and just doesn't feel right. If changing the bearings will fix this, It's worth a try. I saw that replacement bearings from Horizon hobby are running about $9 a piece.

Tycho

RE: Evolution 46 problem (general question)
 

Get a Tower/Aquacraft muffler. They're about 14 bucks, and will "free" some horsepower too! Check Towerhobbies. Get the one for the Tower .46

RE: Evolution 46 problem (general question)
 

UPDATE:

So I decided to try a warranty repair. I boxed up the engine and sent it back to Horizon Hobby including a long letter explaining my problems. Just got the engine back yesterday. They basically rebuilt the whole engine for free. They replaced the crank shaft, both bearings and piston sleeve/liner as well as providing a new glow plug. Now that's great service.

I put the new tower muffler assembly on and now I should be good to go.

RE: Evolution 46 problem (general question)
 

I had the same problem with my evolution PS 46. I was using fuel with 16.4% oil content and 4% nitro, when I noticed a black residue with the oil exhaust. I try to increase for 18% of oil content but the oil exhaust continued black.

Second Dave Gierke, the black residue is from piston wear due the little oil content in the fuel, that is not giving the proper lubrication to engine. This engine should have a minimum of 20% oil for lubrication. Also, for a maximum performance with this engine; use at least 10% nitro.

Them I increase for 20.5% of oil content... the black residue stopped and the oil exhaust is clean.

RE: Evolution 46 problem (general question)
 

My .46 NT does have the black ooze at the muffler halves, but doesn't seem to have any out of the exhaust. I run it a bit on the rich side. No noises or grinding. I was running 15% Coolpower, but recently switched to 15% Omega for the castor.

RE: Evolution 46 problem (general question)
 

It's can be the aluminium dust created by friction in muffler halves. Try tightening the muffler.

RE: Evolution 46 problem (general question)
 

That is what I was thinking.