Trouble with evolution 46 engine. need help!
 

I'm having trouble with my evo, as the title suggests. I've been using it for over a year now (bought used on a plane; was 2 years old when purchased) and have never experienced this since I've had it. All of you people who hate evo's, please don't post here. I'm here for help, not to hear how bad evo's are and your bad experiences with the engine.

It's being wierd. It runs fine for a second on full throttle, then it bogs out. It goes through these cycles (it is high rpm then low rpm and fluxuates back and forth about 2 time a second and eventually dies).

Also, after idling for a while, it tends to die when throttling up. It just stops firing and turns until it stops. I've adjusted the low speed setting from lean to rich about 20 times by now. Sometimes, It won't run after the ignitor is removed. It seems to be losing heat (engine fires slower and slower until it stops).

If it makes much of a difference, it has a OS A3 glowplug running on cool power 15% nitro. These problems started after a hard crash from 500 feet up and down into the woods at the end of last summer (caused by radio failiure, not the engine).<br type="_moz" />

RE: Trouble with evolution 46 engine. need help!
 

Yeah, youi "have a problem Houston". Probably, a leak in the "O" ring at the spigot into the engine case, causing lean runs and not letting the engine shut down with closed throttle. ? [8D]

Sincerely, Richard

RE: Trouble with evolution 46 engine. need help!
 

how do I check that?<br type="_moz" />

RE: Trouble with evolution 46 engine. need help!
 

and whats the spigot? sorry, i'm not an engine guy.

RE: Trouble with evolution 46 engine. need help!
 

You should see an improvement by using an OS A3 plug. You probably do this first, because it would make troubleshooting easier, such as looking for the o ring leak that Richard mentioned.

As for the wet idle condition, go to the hotter plug and then let the engine idle somewhere around 2600 rpm for about 30 seconds. See how it acts when accelerating. Lean the low speed needle if it gurgles or bogs down. You may need to go thru this a few times, but that engine should put out some good power. Then, set your idle rpms where you.

RE: Trouble with evolution 46 engine. need help!
 

Okay. I'll try that, although I was running the A3 when it started to act funky. I replaced it with a new one and it seemed to help. I guess I'll see tomorow. I've had enough messing with it for today. How exactly do I replace this "O" ring that you guys keep telling me about? Where is it? If I'm thinking of the right one, then you guys are talking about the one on the base of the carb, right?

RE: Trouble with evolution 46 engine. need help!
 

I missed a couple of points in your original post, like your using the A3 already.

You can check the external things first, like Spaceworm suggested. I would also tighten down the backplate and change the fuel line from remote needle to the carb. Change your vent line from the muffler, even if it looks good. They can get hot and collapse after a minute or so of running.

The engine is easy to disassemble, and parts are cheap. Have you checked the crankshaft to see if it is still true? Inspect all around the crankcase with a magnifying glass and look for tiny cracks, especially around the mounting tab area.

Have you tried fuel from another jug after emptying your fuel tank?

RE: Trouble with evolution 46 engine. need help!
 

Thanks for the tips. I fixed the idling problem. Now, I'm left with an engine that dies or struggles at about half throttle. All of the internal parts checked out to be fine. I did have to tighten the muffler and put some thread locker on it; I think that was part of the problem. I had it out flying yesterday and didn't realize that the muffler was loose until it was in the air. It flew almost perfect until the muffler popped out of the cowl, then it shut off. That tells me that it was running to rich. However, when I leaned out the mixture and tightened the muffler, I couldn't get it past half throttle before it stalled. I've had this problem in the past, but I cannot remember what exactly I did to correct it.

RE: Trouble with evolution 46 engine. need help!
 

Are sure that you do not have some blockage in the line coming into the needle valve or the needle valve itself?

If you have access to an air compressor take both lines off the needle valve and blow air through the end where the needle valve screws in.

After you do that put the valve back together and hook the feed line to the engine. Once that is done hook a piece of line to the input to the needle valve. Open the needle valve and blow into the line and make sure that air flows through the system.

If you are not using a fuel inline filter, I highly recommend that you install one. Blocked fuel lines and needle valves can cause you to have big issue with engines.

Note I have an Evolution 46 that has many many hours on it. So many that I had to replace the bearings. The engine still runs great and is one of my favorite engines.

Todd

RE: Trouble with evolution 46 engine. need help!
 

I pump fuel in reverse thru the needle valve. I also let the fuel drain into a coffee filter to check for garbage. I had to do this to an Evo .45 that ran into high weeds.

RE: Trouble with evolution 46 engine. need help!
 

If you're running muffler pressure (~3psi), then you lost that pressurization when the muffler fell off that resulted in the engine going very LEAN. Conventional venting (or Uniflow) wouldn't exhibit that kind of behavior, but muffler pressurized systems will.