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General air leak detection?

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Boosted2000si

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Can someone explain signs of an airleak? How do you find where its leaking, and how do you fix it? Are you able to put a sealant on?

I ask cause I have had this aftershock that I can't get figured out. Its been a nightmare out of the box, so it has sat around with no run time on it for almost a year.

I can get it to start, but it always hits this high pitch screaming idle. Not all the time and not at start up, but it after a few pulls on the gas(trigger) it will start screaming high idle. Sometimes I can bump the gas and get it to come down, but most the time I just have to shut the truck off just to keep it from overheating.


Any help would be great.
 
First thing you need to do with the aftershock, is remove the fuel tank primer. I have not had/heard of one that has not leaked. If that dont fix it, get new fuel lines. Stock ones arent that great. That should do it. If not, repost up here, and we'll throw out some different ideas.
Good luck.
 
I have replaced the lines already and pulled the filter off just for testing and it hasent got any better. How can I pull the primer out, I would love to do it, as its junk anyways. I have to hold my finger on the exhaust for prime anyways.


Thanks for a speedy response.
 
Throttle linkage working ok? Not holding the throttle open on you? Sometimes the stock servos go crazy.

When the motor is not revving up real high does the motor surge while idling?
 
Yes the linkage is working fine. The electronics work fine, and the receiver has been upgraded to run on my pro remote.


When the motor idles longer than 20 seconds will just die. The truck has been a pain out of the box.
 
Boosted2000si said:
Yes the linkage is working fine. The electronics work fine, and the receiver has been upgraded to run on my pro remote.


When the motor idles longer than 20 seconds will just die. The truck has been a pain out of the box.
Click to expand...

That sounds like a classic air leak. I still have my priming plunger in my LST but don't use it. I did have to replace all the lines due to air leaks though. You will know for sure if you have an air leak. Just watch the fuel line to the carb. If you see air "gaps" in the fuel stream its time to look into it. Also, you may want to check the o-ring around the fuel cap. If it isn't sealing you will still have the same issue after you remove the primer.

Also, if your fuel filter is routed next to the head as mine was when I got it you might want to re-route it as well. I ended up with a vapor-lock condition where the fuel was getting too hot in the filter when the engine got up to 275-280 degrees. Some say that is too hot for a nitro engine but it is where mine runs best so I'm not going to be too worried about temps. Just don't let it get over 290 degrees!

Good luck and please let us know if this helps or if you need anything else!
 
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I replaced the lines already, rerouted them and removed the fuel filter.


I'm thinking its more of an air leak on the engine. Carb, needles, back plate, head. Something in there. I think I am just going to tear the engine down and RTV the seals.
 
Also check the carb; I use canned air and some after run oil to test for leaks.

Just put a few drops of oil in the carb, and hold it so the intake and venturi (part that goes into the block) are sealed (with your thumb and forefinger). Next, using a little bit of fuel line and the straw, connect your canned air to the fuel inlet, and gently pressurize it. If you have an air leak, you'll see oil bubble out of the spot.
 
If you wanta get serious about testing for air leaks watch this (I swear I did this a week ago)

And for fixing air leaks....
 
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So I did like the video and saw a small leak on the carb, and could feel the loss of pressure as I was blowing into it. So I "sealed" rtv the carb and pull the exhaust off and notice the header gasket to the engine was toasted. So I replaced that gasket and reset the tune to factory and the thing ran a tank of gas with out having any issues. Other than being SUPER rich and wouldnt run with out the glow plug for the first minute, I feel confident its going to be fine. I can't wait till tomorrow to get some tune in on it. I'm am going to break it in a little(Heat cycles) before I start bashing.

Thanks for all the help guys! I honestly am in ahh it took me all these years to find this website. I have tried other forums but nothing like this place!
 
Boosted2000si said:
So I did like the video and saw a small leak on the carb, and could feel the loss of pressure as I was blowing into it. So I "sealed" rtv the carb and pull the exhaust off and notice the header gasket to the engine was toasted. So I replaced that gasket and reset the tune to factory and the thing ran a tank of gas with out having any issues. Other than being SUPER rich and wouldnt run with out the glow plug for the first minute, I feel confident its going to be fine. I can't wait till tomorrow to get some tune in on it. I'm am going to break it in a little(Heat cycles) before I start bashing.

Thanks for all the help guys! I honestly am in ahh it took me all these years to find this website. I have tried other forums but nothing like this place!
Click to expand...

Glad you got 'er done!

BOUTCH said:
Thanks for the vids!!!
Click to expand...

:post_count1:
 

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