need help my engine's connecting rod snapped how can I prevent it - RC Groups
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Mar 13, 2005, 10:50 PM
Registered User

need help my engine's connecting rod snapped how can I prevent it

I am 15 and have an evader, I just have ran about a quart of tower hobbies 10% nitro, with a duratrax hot sport plug. Since I didn't order more fuel I bought some at a hobby store O donnel 20% nitro racing fuel with the same plug. I was driving around, and noticed that the fuel line from the exhaust was brownish, and the fuel coming out was not the usual purple, but brown. Then at mid rpm it just died, I checked it and the rod snapped on the top, scratching my piston. Is it that I didn't use after run oil or too much cause this, or the Donnel fuel was a bad combo with a hot plug.

good thing warantee covers it
thanks for the help
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Mar 13, 2005, 10:55 PM
Deletedfor proving Nauga wrong
most likely you forgot to retune the engine for the new fuel and overheated it.

More nitro = hotter burning in the combustion chamber = you need to richen the fuel-air mix or you get all kinds of bad effects on engines.

I'm suprized the warantee would cover...

MAYBE the engine was just defective and failed. But the description is typical of an overheat caused failure. You can fry any engine in under 3 min by running it too lean.
Mar 15, 2005, 11:42 PM
Registered User
it says 1 3/4 out how about the brown stuff from the exhaust, after I took out the p/s it wouldn't even go up like the piston grew or something
Mar 16, 2005, 12:22 AM
Deletedfor proving Nauga wrong
scraps of the shattered con rod probably got between the piston and cylinder wall... That can freeze the piston in place so bad its only able to be gotten out by driving it out with a hammer and punch (destroying the piston and probably the cylinder... total loss engine in that case.)

Its also probable fragments got in the crankshaft bearings.

Brown, black orsilver exhaust are signs of metal-on metal wear. (silver is extremely serious... it means you may as well be using a grinder on its insides)

Brown is the least serious of the metal-metal wear indicators as its possible to gett brown exhaust just from partially burning somee oils (especially castor.. but if you are burning castor like that... you are WAY too hot.)

Every indication you describe is overheating and /or inadequate lubrication damage.
Mar 21, 2005, 10:26 PM
Professional Crasher
Brown oil discharge is a sign you're running hot and singing the oil. Richen it some when you notice that. Other than that, all I can tell you is to drop in a new power plant and watch its temp.

The piston and sleeve are a matched set and have to be inserted in the right orientation to each other. I put a small mark on the top of my piston toward the notch in the sleeve. Try to turn the piston around 180 degrees and see if you can fit it all the way up.
Mar 27, 2005, 01:21 AM
Registered User
The connecting rod snapping is a sign that the engine has been running too fast and something in the end had to give. How can you prevent it? don't run the car too lean, make sure it is fully run in before giving it a 'hot' fuel and don't rev your car with the wheels off the ground the engine needs the weight of the car too stop it going too fast also make sure their are sufficient holes in the body too keep the engine cool.
Mar 27, 2005, 09:34 PM
Professional Crasher
Exactly, whatch that engine temp as it will tell you if the engine's OL'd or lean, and keep the RPM's in check. Richen it when you see that brown oil discharge, as that means it's too lean for what you're doing, so it's getting too hot. I "roll the window down" to give mine cooling air, that also looks better than cutting a hole in the windshield and may also give more cooling air.
Mar 30, 2005, 11:51 PM
Registered User
thank you guys
Mar 31, 2005, 12:00 AM
Keep 'em Flying
freddy warbird's Avatar
Sounds like it overheated and the rod said @^^#&!*#!*#$!
Mar 31, 2005, 09:53 PM
Professional Crasher
Originally Posted by freddy warbird
Sounds like it overheated and the rod said @^^#&!*#!*#$!
Watch the language now.

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