No Engine Start After Air Filter Popped Off While Driving In Sand

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SSSears

RC Newbie
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Hello,
I recently bought an Exceed Madfire 1/8 Scale .21 4WD Nitro RC Buggy. I broke it in and it was performing well and I began moving on to tuning it a bit more lean after running rich for a few tanks. The other day I was driving and my air filter flew off, but i was unaware since the car's cover was on and there was alot of sand being kicked up by the car. The car shut down so I uncovered it to check for the problem to realise that the air filter was off. There was traces of sand grains on the carb and the carb was sticking, i eventually got the carb free by lubricating it with some nitro fuel and opening and closing it manually. I then proceeded to clean the engine, I flooded it and drained it out to remove the dirt, the waste from the engine was black, i did this about 3 times and then got the engine to start. It shut off again and i never got it started. I tried flooding and draining again and the waste is still black. I am positive that:
1) The carb is opened/closed enough (1mm opening)
2) Fuel is going to the carb
3) The mixture is properly set
4) The glow plug is not fogged up (glowing bright red)
5) The glow starter is very well charged
6) Compression is being made in the engine

Also, one other thing, I am not too sure how the flywheel is supposed to behave. The flywheel can be moved freely anti-clockwise by hand but not to the right and when the pull cord is pulled the flywheel also spins anti-clockwise. I was just wondering if this is correct or if there is a problem with the flywheel.

I am unable to come to a conclusion of what the problem is. Is the engine damaged? Do you guys know what the problem is and how I can fix it?
Any help is appreciated.
 
First off, I would not even try to start it if you suspect some sand got inside the engine. I would take it completely apart to clean and check it out first. Also seal it when re-assembling it. If all is well,then re-try starting it up.

For not starting,one of your six items above has to be false. An engine only needs 4 things to run. Correct air/fuel mixture,igniton,compression and proper timing. I suspect fuel or compression.
 
I see, I realised that I should not have tried starting it. When it comes to fuel/air mixture I am positive that it is correct because I have been running on the same settings all the time. For ignition, the glow plug and starter is working quite well. I am also sure that fuel is getting to the engine, because if I prime while turning the engine over a few times, the engine becomes flooded. Also, I am not quite sure what you mean by proper timing, and how can I tell if i'm getting compression? If compression refers to the engine turning over properly and giving feedback through the exhaust, then i'm having compression. So I am unsure to what the problem may be.
 
If you sucked sand into the engine, it's most likely destroyed. You may have been able to tare it a part and clean it right after the first stall. But by flushing it and turning it over with sand in it, you only finished the destruction. Tare it a part and observe the carnage. I bet you'll find deep scratches in the sleeve at least. Chunks of metal wouldn't surprise me.
 
If you sucked sand into the engine, it's most likely destroyed. You may have been able to tare it a part and clean it right after the first stall. But by flushing it and turning it over with sand in it, you only finished the destruction. Tare it a part and observe the carnage. I bet you'll find deep scratches in the sleeve at least. Chunks of metal wouldn't surprise me.

Agreed.


i always make sure my air filter and kneck are secure at all times, saves this kind of hassle. a cable tie or 2 is a must.
 
a cable tie or 2 is a must.

Absolutely. Secure it with a zip tie. Cut it off when you need to, but keep plenty of spares. NEVER run without it.
(Not even during extended periods of waxing and storage) :hehe:

sav9a.jpg
 
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I keep a bag of 300 in my spares/tool box. To get them on nice and snug I hold them were they loop around the carb throat and use my needle nose pliers to pull them nice and tight. Never had one pop off.
 
I like the PINK zipties, they seen to hold the best.
DSC07906.gif
 
Thank you for your responses. Even though everyone claims that the engine is 'toast', I am quite positive that the engine is in good condition. I opened the engine, the piston moves up and down properly, the is no space on the sides for pressure to be reduced and the compression chamber just looks good overall. I am still unsure to what the problem is.
 
The flywheel can be moved freely anti-clockwise by hand but not to the right and when the pull cord is pulled the flywheel also spins anti-clockwise. I was just wondering if this is correct or if there is a problem with the flywheel.

The flywheel shouldn't be able to move freely in any direction. When the piston nears the top of the cylinder, the flywheel should be pretty difficult to turn over with just your thumb and index finger. If you can spin it freely, in either direction, there's little to no compression in there.

Just my two cents.
 
The flywheel shouldn't be able to move freely in any direction. When the piston nears the top of the cylinder, the flywheel should be pretty difficult to turn over with just your thumb and index finger. If you can spin it freely, in either direction, there's little to no compression in there.

Just my two cents.

I see. I am convinced that this is the problem but are you sure that the flywheel has the same setup on all nitro rc cars? Because if the flywheel is loose wouldn't it be able to spin freely in both directions? Mines spins freely anti-clockwise and if you spin it fast enough you get a little compression out of the engine, and if you spin it clockwise it locks up and pulls the pull cord into the engine. So is it indeed the flywheel? If so, how do I go about fixing this problem with the flywheel?

Also, the engine sounds the same way as before when the pull cord is pulled. Doesn't that mean I'm getting the same compression as when the car was working?
 
The flywheel will turn in the same direction that the pull start pulls it - that is normal. You should have compression though and it should get tight at TDC. You won't be able to turn it backward due to the one-way bearing. It will grab the starter shaft and try to pull the pull-start in but the handle stops it. You can break the string doing that.
 
The flywheel will turn in the same direction that the pull start pulls it - that is normal. You should have compression though and it should get tight at TDC. You won't be able to turn it backward due to the one-way bearing. It will grab the starter shaft and try to pull the pull-start in but the handle stops it. You can break the string doing that.

I see. When I say freely I actually meant with compression but I am positive that my problem is the compression in the engine. When I spin the flywheel and the piston goes up to the top (the point where it has the most compression) the flywheel tightens but barely a bit. When it tightens at this point I can spin it through this tension using my index finger from the bottom of the car with no added strength whatsoever. Does this mean that the engine is getting too little compression? If so, how do I fix this problem?
 
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I see. When I say freely I actually meant with compression but I am positive that my problem is the compression in the engine. When I spin the flywheel and the piston goes up to the top (the point where it has the most compression) the flywheel tightens but barely a bit. When it tightens at this point I can spin it through this tension using my index finger from the bottom of the car with no added strength whatsoever. Does this mean that the engine is getting too little compression? If so, how do I fix this problem?

new piston / sleeve is usually the only way.


you can get your sleeve pinched ( slightly reduced diameter ) but if your piston has scores its wasted money and time.
 
new piston / sleeve is usually the only way.


you can get your sleeve pinched ( slightly reduced diameter ) but if your piston has scores its wasted money and time.

Well I have no way of getting the sleeve pinched, so I'm guessing my option is to replace the piston and sleeve. But the engine is not much more expensive so I should probably replace the entire engine. But, did this problem come about from the sand that the carburetor ingested? Like did it damage the engine causing the lose in compression?
 
have you taken the engine apart yet??


look through the exhuast port ( remove exhaust ) the piston might have scores ( usually the exhuast port side is the first to go )

really you need to strip the engine and get the piston / sleeve out for inspection.


if an engine was not run in properly, it wont last long ( gallon or so if your lucky ) a terrible tune on the lean side on every run will kill it / wear it out fast.



the fact you had sand enter the carb tells me the piston is more then likley buggered along with the crank bearings and possibly the con rod bushes.
 
I see. I'll open the engine when I get the chance to, the furthest I opened it was remove the head and gasket. Can you give me a bit more detailed list of damages to look for before deciding wether anything needs replacement or not?

It's appreciated. I'm new to the nitro stuff.
 
I see. I'll open the engine when I get the chance to, the furthest I opened it was remove the head and gasket. Can you give me a bit more detailed list of damages to look for before deciding wether anything needs replacement or not?

It's appreciated. I'm new to the nitro stuff.



lines on the piston side's= scores

chips on top of piston = damage by debris

lines on the inside of the sleeve = scores



the deeper the lines, the worse it's scored but ultimately all 3 will lead to loss of compression together and individually.



the only other things i can think of are:


glow plug brass washer / gasket leaking.
head shim/gasket leaking.
cracked crankcase / head,
 
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