Air Leak Question

Old 04-28-2011, 08:47 PM
  #1  
Tech Addict
Thread Starter
iTrader: (8)
 
Jake C6R's Avatar
 
Join Date: Jan 2011
Location: Simi Valley, CA
Posts: 557
Trader Rating: 8 (100%+)
Default Air Leak Question

My TRX 3.3 engine was running great and then started burning out glow plugs like crazy. I thought I'd test it for air leaks.

Even with the glow plug issue it was running fine, the HSN and LSN were fine, temps running about 210-230, good smoke trail.

I checked very carefully for leaks using soap bubbles. The bearings aren't leaking at all. The carb neck and bolt is fine and so is the back plate. The only place I found a leak was at the dust boot around the carb slide. I found it had a hole in it so I replaced it and that slowed the leak a lot. However I am still able to blow a little air past it. I don't thing there is any way to completely eliminate it, is there? There is no leak past the LSN itself, only the little bit of air that gets between the carb slide and the carb body, which gets past the dust boot on the end nearest the linkage. Seems normal to me, anyone have any thoughts? Thanks!
Jake C6R is offline  
Old 04-28-2011, 08:59 PM
  #2  
Tech Elite
iTrader: (24)
 
Join Date: Jan 2009
Posts: 2,147
Trader Rating: 24 (100%+)
Default

Air leaks are not likely to pop out plugs like you describe. Air leaks generally mess with your tune, make it hard to find and hold a tune. Time to open it up and have a look.

EDIT, Carb slide boots do not seal a engine, they are only there to keep dirt and debris out. To answer that question, there is nothing you can do about that.
got_nitro is offline  
Old 04-28-2011, 09:39 PM
  #3  
Tech Addict
Thread Starter
iTrader: (8)
 
Jake C6R's Avatar
 
Join Date: Jan 2011
Location: Simi Valley, CA
Posts: 557
Trader Rating: 8 (100%+)
Default

Yeah I am thinking it is something else. I also checked the fuel tank, no leaks there either.

I am not having any erratic idle or problems once it is running, it's after I run out of gas and try to restart after refueling, the plug is dead.

I pulled the head and the piston looks great. Gold/tan color, no signs of a lean condition or detonation. I have always used MC-59s with good results. Maybe I got some bad ones. I'm pretty much out of ideas.
Jake C6R is offline  
Old 04-29-2011, 05:38 AM
  #4  
Tech Elite
iTrader: (24)
 
Join Date: Jan 2009
Posts: 2,147
Trader Rating: 24 (100%+)
Default

Originally Posted by Jake C6R View Post
I am not having any erratic idle or problems once it is running, it's after I run out of gas and try to restart after refueling, the plug is dead.
What color is the element when you pull it out? What kind of fuel are you using?
got_nitro is offline  
Old 04-29-2011, 07:36 AM
  #5  
Tech Addict
Thread Starter
iTrader: (8)
 
Jake C6R's Avatar
 
Join Date: Jan 2011
Location: Simi Valley, CA
Posts: 557
Trader Rating: 8 (100%+)
Default

Originally Posted by got_nitro View Post
What color is the element when you pull it out? What kind of fuel are you using?
The plug looks a little wet, a little more black than silver. When they die they look almost new. I am running Byron's 20% fuel, that is the only kind I have used.
Jake C6R is offline  
Old 04-29-2011, 08:07 AM
  #6  
Tech Addict
iTrader: (8)
 
Join Date: Mar 2010
Posts: 614
Trader Rating: 8 (100%+)
Default

To much rod slop or rear bearing shot or tune waaaaaaay off.
bacchus is offline  
Old 04-29-2011, 08:44 AM
  #7  
Tech Regular
iTrader: (16)
 
Join Date: Mar 2011
Posts: 479
Trader Rating: 16 (100%+)
Default

Originally Posted by bacchus View Post
To much rod slop or rear bearing shot or tune waaaaaaay off.
i agree with the rod slop. check the bushing at the end of the rod . i had same issue several years ago when i was in florida. turned out to be the rod bushing on the crank. wasn't much left of the brass ....
GASSPRINT1 is offline  
Old 04-29-2011, 08:52 AM
  #8  
Tech Addict
iTrader: (1)
 
Join Date: Apr 2009
Location: Surprise
Posts: 633
Trader Rating: 1 (100%+)
Default

How old is the fuel and where do you store it? If you keep it in the garage and it is hot it will mess your fuel up. Your tune may be way off. Go bact to factory settings and tune from there. Your top end may be way lean and the bottom fat or vice versa. Good luck.
Sparky4u is offline  
Old 04-29-2011, 09:06 AM
  #9  
Tech Master
 
nitroexpress's Avatar
 
Join Date: Sep 2006
Posts: 1,919
Default

Originally Posted by Jake C6R View Post
My TRX 3.3 engine was running great and then started burning out glow plugs like crazy. I thought I'd test it for air leaks.

Even with the glow plug issue it was running fine, the HSN and LSN were fine, temps running about 210-230, good smoke trail.

I checked very carefully for leaks using soap bubbles. The bearings aren't leaking at all. The carb neck and bolt is fine and so is the back plate. The only place I found a leak was at the dust boot around the carb slide. I found it had a hole in it so I replaced it and that slowed the leak a lot. However I am still able to blow a little air past it. I don't thing there is any way to completely eliminate it, is there? There is no leak past the LSN itself, only the little bit of air that gets between the carb slide and the carb body, which gets past the dust boot on the end nearest the linkage. Seems normal to me, anyone have any thoughts? Thanks!
What fuel are you running and how much fuel has been run through the engine?
nitroexpress is offline  
Old 04-29-2011, 09:06 AM
  #10  
Tech Addict
Thread Starter
iTrader: (8)
 
Jake C6R's Avatar
 
Join Date: Jan 2011
Location: Simi Valley, CA
Posts: 557
Trader Rating: 8 (100%+)
Default

Thanks for the replies, I'll check the rod slop as well. The thing has not even 2 gallons through it yet. Fuel is about 4 months old, about 1 quart left on the gallon that was stored on a shelf in the garage with the excess air squeezed out. The fuel works fine on my other cars so I think it's fine. I'm also going to clean and rebuild the carb then start over on the tune from the factory settings. If that doesn't do it then I may have to resort to violence on this engine and get a new OS
Jake C6R is offline  
Old 04-29-2011, 10:59 AM
  #11  
Tech Master
 
nitroexpress's Avatar
 
Join Date: Sep 2006
Posts: 1,919
Default

Originally Posted by Jake C6R View Post
Thanks for the replies, I'll check the rod slop as well. The thing has not even 2 gallons through it yet. Fuel is about 4 months old, about 1 quart left on the gallon that was stored on a shelf in the garage with the excess air squeezed out. The fuel works fine on my other cars so I think it's fine. I'm also going to clean and rebuild the carb then start over on the tune from the factory settings. If that doesn't do it then I may have to resort to violence on this engine and get a new OS
Being a TRX, just wondering if you use Traxxas fuel (bad idea). Traxxas fuel with a break in at too low a temp could blow out your rod easily. Get an OS and properly break it in.
nitroexpress is offline  
Old 04-29-2011, 11:03 AM
  #12  
Tech Apprentice
iTrader: (5)
 
Join Date: Jan 2011
Posts: 53
Trader Rating: 5 (100%+)
Default

i read another post on another web site guy had same problem and there was a small piece of (dirt steel) floating around in his motor so i think a tear down and rebuild will possibly fix ur issue!! it fixed his
tnxman is offline  
Old 05-01-2011, 10:11 AM
  #13  
Tech Addict
Thread Starter
iTrader: (8)
 
Jake C6R's Avatar
 
Join Date: Jan 2011
Location: Simi Valley, CA
Posts: 557
Trader Rating: 8 (100%+)
Default

Originally Posted by tnxman View Post
i read another post on another web site guy had same problem and there was a small piece of (dirt steel) floating around in his motor so i think a tear down and rebuild will possibly fix ur issue!! it fixed his
I have it completely torn down and I didn't find anything inside. The piston and sleeve look good and there is good pinch. The only thing that may be off is that the connecting rod bushing looks like it may be a tiny bit more worn on one side than the other. However when I put it on the crank I can't really get any noticeable slop. Even so I am going to replace it - I should have the new one in a couple days. I'm also going to seal it up with Lucky 7 sealant once I put the rod in. I will post the results when done.
Jake C6R is offline  
Old 05-01-2011, 09:55 PM
  #14  
Tech Initiate
 
cbengsch82's Avatar
 
Join Date: Jul 2010
Location: Reeseville, Wisconsin
Posts: 29
Default

I had a problem similar to this with my sportwerks .26 v2. Couldn't figure out the problem and even opened it up multiple times. I finally noticed that where the one-way bearing assembly rode on the backplate, pieces of the backplate were chipping off. Don't know why it was but after a cleaned it all out and put in the new backplate, I never had the problem again. Sounds to me like there is something bouncing around in your engine. It doesn't take much to do any sort of damage. Try washing out the engine.
cbengsch82 is offline  
Old 05-01-2011, 10:28 PM
  #15  
Tech Elite
iTrader: (55)
 
jpalessi's Avatar
 
Join Date: Feb 2008
Location: SoCal
Posts: 4,747
Trader Rating: 55 (100%+)
Default

What glow plugs are u using?
jpalessi is offline  

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


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.