R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro Off-Road

Reply
 
Thread Tools Search this Thread
Old 10-16-2008, 02:00 AM   #1
Tech Adept
 
Join Date: Jul 2008
Posts: 234
Default air leak?

i had my motor out for a few weeks while i gathered parts for diffs and big bores and i put the motr back in and the thing revs real high but the carb is closed as normal as it used to be. coult this be a result of a bad o ring under the carb? its a v spec. rc8
ruggydriver is offline   Reply With Quote
Old 10-16-2008, 03:49 AM   #2
Tech Regular
 
bjr48's Avatar
 
Join Date: Apr 2008
Posts: 274
Default

If the carb is closed and the engine revs it is almost for sure an air leak but where? You could have just as easily torn some fuel tubing when you removed the engine.
I would remove the fuel tank and every last inch of the lines and pressure check them in a tub of water. If you don't find any leaks, get a set of those rubber caps from the hobby store, take off the air filter and exhaust and cap them off. Put a small length of fuel tube to put on the fuel nipple on the engine that you can blow into and use something like plumbers leak finder from the hardware store or soapy water. Just don't submurge the eninge in water, spray something like that all around places it could leak (carb neck, any of the needles, front bearing, backplate, etc.) and blow into the tube to pressurize the engine looking for bubbles. Make sure you clean all of what you use off the engine with whatever you normally clean it with and dry it off when you are done. good luck! If you don't find anything, replace the fuel tubing and check the engine one more time. They can be very hard to find sometimes. Put the engine back in a try it again. Also check your seals on your manifold and pipe but I don't think those can cause as much trouble as you are describing.
bjr48 is offline   Reply With Quote
Old 10-16-2008, 07:59 AM   #3
Tech Elite
 
jpalessi's Avatar
R/C Tech Elite Subscriber
 
Join Date: Feb 2008
Location: SoCal
Posts: 4,747
Trader Rating: 55 (100%+)
Send a message via AIM to jpalessi Send a message via Skype™ to jpalessi
Default

also check your carb boot for any pin holes.. that's all it takes.

http://www.amainhobbies.com/product_...ducts_id/25728
__________________
Joe Alessi
www.Lucky7RC.com
jpalessi is offline   Reply With Quote
Old 10-16-2008, 08:51 PM   #4
Tech Regular
 
xyzyx00's Avatar
 
Join Date: Oct 2008
Location: SoCal
Posts: 251
Trader Rating: 4 (100%+)
Default

-brainstorming- i was running an external fuel filter with mine and every now and then my engine would start to idle high while i was running and then trail back down a few seconds after comming to a stop. turns out it was leaning on the top end due to my restrictive filter, it wasnt even dirty. i have one in my tank so i just removed it and the think runs like a champ...
xyzyx00 is offline   Reply With Quote
Old 10-17-2008, 09:38 PM   #5
Tech Adept
 
Join Date: Jul 2008
Posts: 234
Default

how to presure check the tank and fuel line in a tub? im bit confused on that part
ruggydriver is offline   Reply With Quote
Old 10-17-2008, 11:46 PM   #6
Tech Master
 
Join Date: Aug 2006
Location: Oceanside CA
Posts: 1,075
Default

Take tank out of car. Put fuel line on pressure tap. Put finger over fuel outlet. Submerge tank in bucket of water. Blow on line connected to pressure tap. Any bubles means bad. Lid should not pop up & leak bubbles,humans cant blow that hard, if it does that mean bad. This will not tell you if theres an internal leak where the plastic line inside the tank going up from the filter meets the the line inside the tank that turn 90 degrees & exits through the back of the tank. Internal leaks suck(just ask an RC8 owner,OH wait a second) as the fuel level drops below the leak the exaust coming in from the pipe goes in that leak & leans the crap out of the motor randomly because the filter is now not the only place pressure can go through. You may get lucky if the leak is real bad & see air bubbles in the line coming out of your tank if this is the case. I couldnt see bubbles in my line but puttiong a mugen mbx5r tank in fixed the problem. Its a direct fit if you want to bend the tank mount posts at the bottom 3-4 mm. Now that I got rid of that piece of crap I gave the tank to a friend that still hasnt wised up yet. You can see pictures & descriptions of how to install 3-4 different tanks in the RC8 if you search the ass website forum. They will give you a new tank if you send yours in but say theres no problem with the tank even though their on their 3rd revised tank. Scroll 1/2 way down the link,the pictures of the white car is mine(was mine now some other suckers).

http://www.aeforums.co.uk/forum/inde...opic=2061&st=0
butch man is offline   Reply With Quote
Old 10-18-2008, 12:05 AM   #7
Tech Adept
 
Join Date: Jul 2008
Posts: 234
Default

i think tomarrow morning im going to fill the tank up completly and try it


then iif it still happens
new fuel line

if it still happens ill start going into more depth lol
ruggydriver is offline   Reply With Quote
Old 10-18-2008, 12:19 AM   #8
Tech Master
 
Join Date: Aug 2006
Location: Oceanside CA
Posts: 1,075
Default

Its your time to spend how you like but you've seen the ae forum results how it will end. I can tell you one thing though those big bore will make the RC8 a whole new car so dont waste too much time.
butch man is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
OC CIRCUIT v.2 Intelligentsia California Racing 10451 06-15-2015 10:29 PM
This V-spec is driving me insane. Jonro Nitro Off-Road 95 03-30-2009 02:35 PM
V-Spec front bearing issues Jonro Nitro Off-Road 35 09-06-2008 10:04 PM
engine air leak?? oderem Nitro On-Road 13 07-12-2006 01:55 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 07:59 AM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net