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Dirty fouled plugs?

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dino451

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Hello everyone, new to the forum not to nitro (10 years). My buddy is having an issue with his Axial .28 engine. It keeps fouling plugs even brand new ones. Another issue the engine turns off as soon as you remove the glow starter or sometimes stays running for a few seconds.

it seems very rich, but the last time is was ran (one week ago, about the same weather) it was fine and the needles were not changed. The plugs come out dirty, oily and the coil is not aligned or a little mangled. He recently took apart the engine because his air filter failed and possibly let dirt into the engine. He reassembled put a used plug in ran fine a week ago now since then its been going through a few plugs under one tank each, and now it wont stay running without the glow starter. let me know of any more details that you need. Anyone got an idea?
 
Think your kinda answering it yourself with it running rich. The only thing I would be concerned with would be the mangled coil. If your burning the right glowplug than it shouldnt be touching the piston or anything else. Is it possible he forgot to put the shim on the head when he reassembled it? Otherwise I'm stumped.....
 
I agree with Phines about the shim and it running rich. the motor dieing when you take the ignighter off means bad plug .plug is probably only getting hot enough to start with the ignighter on it when you take it off only part of the plug is still glowing and the motor dies.does the bottom of the plug look like the piston is hitting it .allso look in the hole with a flash lightt to see if the piston has any marks on the top.
 
Ballen said:
I agree with Phines about the shim and it running rich. the motor dieing when you take the ignighter off means bad plug .plug is probably only getting hot enough to start with the ignighter on it when you take it off only part of the plug is still glowing and the motor dies.does the bottom of the plug look like the piston is hitting it .allso look in the hole with a flash lightt to see if the piston has any marks on the top.
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Thanks! I will double check his work and ask him about the shim. The thing is he says he didn't touch the needles. Will also check the piston and plug to see if they are hitting.
 
Bearings are a lot cheaper than multiple glow plugs. Nitro engines need tuned every outing. If the engine was forced to run excessively rich, that puts stress on all the internals. Which kills bearings. A nitro engine can not run correctly with worn out bearings.
 
Nitro engines need tuned every outing
I disagree with that. My XL sits for days and even a week or two sometimes and I can't remember the last time I took my screwdriver with me for an outing and it still runs great.
 
If the weather is the same then yeah, little or no tuning needed. But if there's a 20 degree difference outside, or even ten, you need to tune. Same goes for humidity and barometric pressure.
 
2revo hit it right. If theres little to no change in the ambient temp than theres little to no change with the tune. I cannot think of anyone I've come across who ran a car in say July and put it away until say December and it fired right up with no adjustments. You will always need to adjust to your atmosphere. The temp severly affects the oxygen% and how much or little your powerplant will need to breath:p:
 
You'll have to pop it apart and check the crank bearings. How's the top of the piston look? Anything stuck to it? Is it pitted?
 
2revo1maxx said:
You'll have to pop it apart and check the crank bearings. How's the top of the piston look? Anything stuck to it? Is it pitted?
Click to expand...

I haven't had a chance to follow up with him yet. The first chance I will get wont be until Sunday. Thanks for everyone's quick responses I will try to update as soon as I can.
 
Just followed up with him. He bought a new plug, reset the needles to factory settings but I couldn't be their when he ran it so I don't know what happened. He tells me that he put the shim back, he did not notice any pitting, sleeve and piston were fine and shiny. He went to our local hobby shop and mentioned to them mid speed needle kept backing out even with threadlock. I knew about this but forgot to mention it. Could this be the cause of his problem? They told him he might need a whole new carb because that needle should not have been touched at ALL.
 
The engine seized on him. Removed the head and lots of small chunks of metal on top of the piston. Don't know right now what broke but the piston could not be moved and he told me that he had to lean it way out (1.75 turns! From closed) just to run correctly, yeah so he's really bummed out now. Thanks for everyone's help on this.
 

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