Excessive fuel out the front bearing  
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All Forums >> RC Airplanes >> Pylon Universe - RC Pylon Racing >> Q-500 Racing >> Excessive fuel out the front bearing Page: [1]

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Excessive fuel out the front bearing - 4/2/2002 3:20:48 AM   
Bozarth


 

Posts: 185
Joined: 4/30/2004
From: Centennial, CO, USA
Status: offline 		Would someone address what a normal amount of fuel leakage out of the front bearing is for a Nelson? I aquired a used motor and it seems excessive. Runs strong but seems to spit out more raw fuel through the front compared to my others. Thanks.
       Post #: 1

Excessive fuel out the front bearing - 4/2/2002 4:44:44 AM   
Randy Smith


 

Posts: 133
Joined: 1/3/2002
From: Calgary, AB, CANADA
Status: offline 		Hey Kurt,
You might have one of the old Nelson engines from five or six years ago. Many of these engines spit a lot of fuel out of the front bearing. From what I know, there is nothing wrong with your engine and it's perfectly normal for this vintage.

I do not know what the reason for this is. Something in Henry Nelson's design at that time. If you want the real answer or have further concerns, contact Dave Shadel at Performance Specialties. Dave's email is [email]perfspec@775.net[/email]


Randy

(in reply to Bozarth)
       Post #: 2

Excessive fuel out the front bearing - 4/2/2002 9:09:06 AM   
pylon racer



Posts: 66
Joined: 3/6/2002
From: Vienna, VA, USA
Status: offline 		I believe the fuel out the front was to help lube and cool the bearings.

(in reply to Bozarth)
       Post #: 3

Excessive fuel out the front bearing - 4/2/2002 11:52:56 PM   
splatt



Posts: 651
Joined: 1/30/2002
From: splattsville, MN,
Status: offline 		The rossi's I have dont have a sheild on the front bearing so there's plenty of lube for the bearing. I have an old jett that I can take a shower with when I'm behind it, same thing no sheild on the front bearing. I got a boca bearing for the rossi that was sheilded for a sport plane, but maybe check with the nelson guru's for maybe a better bearing

(in reply to Bozarth)
       Post #: 4

Excessive fuel out the front bearing - 4/3/2002 3:15:22 AM   
R.Bridge


 

Posts: 128
Joined: 3/22/2002
Status: offline 		I have also seen some motors spit more fuel out the front bearing than others. I think this would be more due to the clearance between the outside diameter of the crank and the inside diameter of the case. The more clearance between the two the more fuel would be able to pass through. I can't really confirm that this would be a bearing problem, I would lean more towards crank and case clearance.

I believe I got that right from Shadel a few months ago after I noticed one of my friends motors doing the same thing. Call him to verify.......

just a thought ??

Randy Bridge

(in reply to Bozarth)
       Post #: 5

Excessive fuel out the front bearing - 4/3/2002 3:19:17 AM   
Bozarth


 

Posts: 185
Joined: 4/30/2004
From: Centennial, CO, USA
Status: offline 		Excellent responses. Thank you. Kurt

(in reply to Bozarth)
       Post #: 6

Excessive fuel out the front bearing - 4/3/2002 7:08:30 AM   
daven



Posts: 7004
Joined: 12/7/2001
From: Andover, MN, USA
Status: offline 		I'm thinking its an older Nelson design.

I believe the older nelsons had a hole or path for fuel to run towards the front bearing for lubrication and cool down.

Not positive, but I thats my take.

_____________________________

Dave Norman

klasskote.com
supertrc.com

(in reply to Bozarth)
       Post #: 7

Excessive fuel out the front bearing - 4/3/2002 8:44:13 AM   
PylonWorld



Posts: 1346
Joined: 12/29/2001
From: Monroe, NC, USA
Status: offline 		I was holding a Quickie Jett powered plane and getting more cold spit than warm spit, and the engine was erratic. Changed the plug, and it changed. Checked the engine front to rear and something was loose on the RNV or the airvalve carb. And it was only a little loose ... Sorry I can't remember what it was.

But check all of the fuel feed system. It happened with a pinhole in the fuel line one time also.

You can actually feel the difference in the temp of the spit from different locations ... so take a spit temp test on one of the others and see how it compares.

_____________________________

Don Stegall
RCPRO Chairman of the Board

(in reply to Bozarth)
       Post #: 8

Being spit-on by a ST X Series 40. - 4/3/2002 10:25:18 AM   
MaxQ


 

Posts: 91
Joined: 2/10/2002
From: Santa Clara, CA, USA
Status: offline 		I have a ancient ST 40 X series that passes lots of "cold" spit out the front bearing. Still runs strong, but always wondered, if its pumping raw fuel out in one stroke what is it pulling in during the other stroke?? Confused. Is this a sign of bad things to come? Is Boca bearing my best shot at replacements for a 15+ year old engine?

(in reply to Bozarth)
       Post #: 9

Excessive fuel out the front bearing - 4/3/2002 7:31:50 PM   
splatt



Posts: 651
Joined: 1/30/2002
From: splattsville, MN,
Status: offline 		I think these older hi-rev engines have either a groove or a hole in the crank to allow fuel to cool and lube the bearings. Thinking that bearing technology wasn't what is was compared to today with plastic cages and todays alloys designers made sure to keep there engines alive with plenty of lube.
I dealt with boca bearings a couple of times and its a one phone call deal and your done.
My old jett spits and surges whens it on the ground, but let it go and it sings a fine song, can't wait to get out, this bench racing is driving me crazy

(in reply to Bozarth)
       Post #: 10

Excessive fuel out the front bearing - 4/3/2002 8:25:10 PM   
PylonWorld



Posts: 1346
Joined: 12/29/2001
From: Monroe, NC, USA
Status: offline 		Speaking of bench racing, my new G2 will be here today, and I'll finaly be able to race you on the G2 racing server in full capacity ... watch out ... for my planes that is.

_____________________________

Don Stegall
RCPRO Chairman of the Board

(in reply to Bozarth)
       Post #: 11

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