JL .28 connecting rod

[RCN]

Well guys I've had my hyper 7 with the 28 engine for a little over a week and took all day to break it in and today I was running it in some grass and it cut out after it passed me (mind you all this happened in about 75 feet) I went over to it thinking it had just flamed out or something simple. I went to pull it over and the pull cord wouldn't even move. I figured it was just really hot so I let it cool down for a little. While it was cooling down I inspected everything and noticed the flywheel would move but not the piston when I looked down through the head button. Instantly knew it was the rod. Got it home took it apart and took pics of all the damage. I've run it rich as its cooling off here temp wise. I've been through about 2/3 of a gallon of fuel and looking at the rod itself it looks like part of it that wraps around the bushing shattered and then it just went to hell from there. There's no damage to the bushing except where the rod stopped it while running. Also parts of the piston are missing and theresmetal dust everywhere in the engine and pipe. I'm thinking its a defect in the metal itself as I inspected this engine about 4 days ago out of pure curiosity AMD everything was tight and as it should be. I even oiled it at the bushing and pin.

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Let me know if the pics don't show up

 

[griff7373]

no pics, you may want to try for a warranty claim.

 

[RCN]

I missed the 10 day window to register the buggy with ofna so I'm sorta screwed there but I emailed the hobby shop I purchased the buggy from with pics so I should hear back on monday. This just really sucks because I know I wasn't too lean or anything like that. The engine wasn't even abnormally hot after it locked up on me :/ I'll let y'all know what happens and I'll try and post a pic of the damage..

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Its still not letting me upload a pic :/

 

[RCN]

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Here's a link to the pic before I pulled it apart all the way. I hope it works, I'm using photobucket so I'm not sure what's going on with the pics..

Also I should hear back about the buggy tomorrow. Hopefully something can be done. If I have to fix it myself do you think I would be better off getting a different engine (same engine but 100% new or another brand engine) or rebuilding this one? I've read mixed reviews on this engine and I was happy with the performance of it but I hated 2 things about it, it was a bear to start when cold (engine temp wise) and it would load up really fast on bottom end whether I leaned it out or not. Yesterday was the second time I had run it in grass and then boom all this happened.

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Here's another pic.

One thing I noticed that I thought was really weird was all the metal dust in the engine. I'm not a novice mechanic by any means and with all the blown up engines I've ever messed with I've never noticed metal dust like that. Especially when connecting rods go out like this. Could a piece of the piston broken off and just pulverised everything else in the engine? I can only find one piece of the piston skirt. The other piece is long gone. There was a lot of metal on top of the piston but after wiping it down its evident that 90% of the metal fragments stayed in the bottom end.

 

[griff7373]

Anything is possible, it looks like the conrod also is bent along with it blowing apart. Should it not be handled under warranty I would definitely go with another brand engine.

 

[RCN]

What brand engine would you recommend? I'd like to stick around the .21 range actually. Plus how would I determine if I need a different exhaust manifold? What's the difference between a true big block and a small block exhaust manifold size?

Oh and yes the connecting rod is rippled above where the bushing would be

 

[2revo1maxx]

Sorry, but it was run too lean.

 

[RCN]

Its not possible seeing as how I had a full tank from start, and was still running a very rich tune. My HSN was 3 1/4 turn out and my LSN was a few hours shy from a full 2 turns out from flush. The glow plug had oil/ unburnt fuel on it and the top of the piston was starting to get the brown coloration to it. The smoke trail was very thick and it was consistant. Plus I'm sure that if it was too lean it would have failed much much sooner.

 

[2revo1maxx]

You said you had dust inside the engine, but didn't show a top view of the piston, so I guessed it must have been lean.
Now I'm going to say you never allowed it to warm up. All that "pinch" is extremely hard on an engine. You must allow it to reach 200 degrees while still running rich. It must have ran tight all that time causing the rod to fail.

 

[RCN]

Metal dust. Meaning possibly the piece of the piston skirt that I can't find. And during break in I got my temps up to around 210 to 220F and before I even tried to start it I preheated the engine to over 200F. There is no damage to the top of the piston. Its still smooth and flat and the piston was slowly turning a brown color on the crown. As for letting it warm up I give it anywhere between 30s and a minute to warm up before I even move it. Then after that I run around gently until I can feel heat throughout the engine. Then I run it like I normally would and even then I don't run it hard for very long. As for the amount of pinch left it was 99.9% gone. The engine had great compression and there wasn't a stiff spot in the engine when the glow plug was out. I'm not trying to start a war or anything but dropping $300 on this and having this fail so soon in such a horrible way was not my idea of a good Saturday afternoon :/ but on a good note the dealer is replacing the whole buggy for me seeing as the damage caused seems more like a manufacturing defect than something I did intentionally or unintentionally. It will hopefully be shipped out today and I may have a new one by Friday at the earliest. I'm not 100% sure on that yet.

 

[Bashing_Nitro_Carnage]

Hello You noted something about your skirt being damaged. Let me ask, did you open the back plate at all (to seal it or whatever prior to this happening)? Irregardless of if you did, do you recall how much play was in the crank shaft. When I hear the skirt was damaged I'm just wondering if it was damaged when removing/re-installing the back-plate...thus causing this catastrophic failure...OR if perchance you lost one or more bearings during break in--it can happen--causing such extreme play with the shaft rod moved past it's insert, pulling the skirt with it enough to get damaged? The inside of these nitro engines are among the most violent places the earth has to offer so you can imagine being off a mm or two. The main thing is you are up and running again (at least so I hope).
With that, we've all snapped a few roddies in our day, no? I sure have. I seem to be the only one who was responsible for snapping his as well ha ha .Oh, it was all my fault. Ran the engine too hot for too long, too early. Lesson learned. I'm leaning toward you running it too hot as well as that is by far the most likely scenerio. Not often they self implode.

 

[RCN]

I pulled the backplate just out of curiosity and I checked over everything. There was plenty of oil over all the internals and there was no noticeable play in the crankshaft and when I reassembled the engine the piston was at TDC as to avoid any contact with the backplate. As for the new one it has had exactly 10 tanks through it and hasn't been run in about I'd say almost a month now. 3 reasons. Money is thin. It's getting colder faster than thought outside. And I've sort of lost interest in the hobby seeing as after searching for a long time there's not many other nitro guys around here. So I cleaned it up and stored it in its box. It was really exciting at first but with the way things are I'm on the fence about selling it or keeping it. Not sure what I'm gonna do yet but if I did sell it I'd like to get at least $300 for everything seeing as its still practically brand new. There's one small scratch from a kicked up rock on the underside of the chassis but with the "used" stuff from around here mine looks brand new in comparison.

 

[Bashing_Nitro_Carnage]

Gotcha. Well, sorry to hear this, but it probably is for the best. It's better to know now than after you really invested...the more you put your hands on these vehicles the more often things can go wrong. I'm new here so can't speak for anyone else, but as deeply twisted as it sounds...the more I am fixing the better I am getting. Because this hobby is not for everyone. It's like having 'heart' in boxing, Because regardless of what type of chin anyone might think they have...this nitro rc hobby will knock you down, and upside down, and laugh, when its conquered and won 1 Like I said, I;'m new here but imagine there are many dedicated to holding down fort so in the event you decide to come back and handle unfinished business....it's here for you. LOL
One other thought is it could have bee running sloberring rich (3 turns out on the LSN is a lot. Normally that is leaned in a tad to keep the vehicle running, followed by HSN to raise temps). Perhaps you were running quasi-hyrdrolocked. Did your sleeve ever get suck a TDC? That is not damaging in itself, but freeing of the sleeve can put strain on a young rod-bushing. Just another consideration on the event you do go in for round two.
JF

 

[olds97_lss]

I watched two bulletproof engines grenade like that before. One at a gallon and one after about a quart. Neither really made sense as it was a newer guy to the hobby, but I ran pretty much every tank with him at the time and the engine was an OS21RG, which if anyone has had one knows you can nearly fill it with gravel and it will be fine. Don't know if it as a manufacturing defect or just bad luck, but after the second one grenaded just like yours at 1 quart, he got a hot bodies powerhouse 26 and beat the crap out of it and it was fine.

As a basher, I can see how it's somewhat defeating and lost some of it's luster. I've put my rigs on a rack for a year or two, then get a bug up my butt and start running again. I run alone all the time now. Been in the hobby for 15+ years and out of those 15, I've had maybe 3 years where I ran with other guys. Trust me, it can still be fun on your own. After not running since last year, I fired up my revo a month or so ago and decided to throw another fist full of money at it for a new engine. Kind of reinvigorated my interest again. Now I'm trying to figure out which rig I want to adjust for winter running...