VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-7/7A
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 03-05-2017, 11:25 AM
ELEDSALL ELEDSALL is offline
 
Join Date: Sep 2007
Location: OKLAHOMA
Posts: 10
Default ROUGH ENGINE - POOL OF BRAKE FLUID

My latest attempt to run mogas in my Superior O-360 was not good. I had good luck running it until the temps warmed up and then problems. I suspected that my rough idle was due to mogas so I drained one tank and replaced the gas with 100LL. No problems in the flight around the patch. After landing, I switched to the mogas tank to see if it was indeed the problem. Sure enough, before I could return to the hangar my engine was barely running; coughing and loopy idling. Super I thought; no engine problem just mogas.

After I limped back to the hangar, I felt my right brake go soft. After shutting down, I noticed an ever larger pool of brake fluid forming around the right tire. I rolled the bird back in the hangar and within a few minutes, I had a pool around the left tire. I thought that the vibration might be enough to brake the al tubing that runs down the gear leg. I ordered braided lines and installed them this a.m. As I went to reverse pump/bleed the brakes, fluid immediately started running out of the brake caliper. I had not found any breaks in the al tubing so I was already questioning my analysis.... now I am baffled. Ideas please.
Reply With Quote
  #2  
Old 03-05-2017, 11:31 AM
flightlogic's Avatar
flightlogic flightlogic is offline
 
Join Date: Nov 2013
Location: Prescott, AZ
Posts: 1,289
Default choices

One of the upsides to your experience is getting good braided lines right away. I have been suspicious of the solid lines on any RV.
When I look at my total investment in my plane, insurance, training and so forth... I voted against mo-gas. When all is said and done, not having any stinky residue around... a known, clean highly refined gas makes me happy.
When it comes to oil changes and fuel... I just chalk it up to the cost of aviation. And your engine will go back to smooth.... I hope.
__________________
"Kindness is never a bad plan."
Reply With Quote
  #3  
Old 03-05-2017, 12:07 PM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,093
Default

In all probability its leaking from the O-ring on the caliper piston. Take it off for a look see.
__________________
David C.

RV-10
Flying as of 12/29/2013
Howell, MI

SOLD 08/23/2016.
Looking for a project!
"Donor Exempt" but donated through Dec. 2017
Reply With Quote
  #4  
Old 03-05-2017, 12:13 PM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,093
Default

Quote:
Originally Posted by 9GT View Post
In all probability its leaking from the O-ring on the caliper piston. Take it off for a look see.
As far as using mo-gas: I built my RV-10 with that in mind and made sure I routed and insulated all the FWF lines against heat, and also used a blast shield around my engine mounted fuel pump. I was careful in my testing but eventually found that even on hot days, I had zero issues with the fuel vaporizing. I would still keep fuel separated in the tanks: Left tank mo-gas and right tank 100LL. I would take off and land on the 100LL and cruise on the mo-gas. The engine never stumbled or missed a beat and I save a lot of money!
__________________
David C.

RV-10
Flying as of 12/29/2013
Howell, MI

SOLD 08/23/2016.
Looking for a project!
"Donor Exempt" but donated through Dec. 2017
Reply With Quote
  #5  
Old 03-05-2017, 01:43 PM
John-G John-G is offline
 
Join Date: Jan 2012
Location: Northeast Ohio
Posts: 343
Default

ELEDSALL -

I suspect you have run into the issue of auto fuel that has been formulated for winter. The winter formula allows the fuel to vaporize easier in lower temperatures .... as long as winter temps are cold you are in good shape. However, it gets really dicey when using the winter formula fuel when it gets warmer in the Spring.

I have read that when the temperatures get warmer, the vapor lock issue can be mitigated significantly by adding 30% of 100 LL to the winter fuel blend.
__________________
John
www.dogaviation.com
RV-12 Wings, Empennage, Fuselage, Finishing, Avionics and Powerplant kits all completed
Now Flying!!

Dues paid until September 2017
Reply With Quote
  #6  
Old 03-05-2017, 01:57 PM
ELEDSALL ELEDSALL is offline
 
Join Date: Sep 2007
Location: OKLAHOMA
Posts: 10
Default

Thanks everybody for your thoughts and comments. Is it possible that the engine vibration caused both brake calipers to leak?
Reply With Quote
  #7  
Old 03-05-2017, 02:05 PM
Ralph Inkster Ralph Inkster is offline
 
Join Date: Feb 2008
Location: Calgary, Alberta
Posts: 265
Default

Murphy's Law.
Brake O-rings can go anytime. Same with over tightened brake line flares. Be thankful it happened at your home field.
__________________
Ralph
Maintain lots, upgraded & repaired some, modified more, rebuild a few, & built 4 of 'em
Reply With Quote
  #8  
Old 03-05-2017, 03:13 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 4,110
Default

Have you, or anyone, had the brakes apart? It is possible to re-install the piston backwards, so the O ring is very near the top rather than well down in the cylinder. After the pads wear just a bit, applying brakes can let the O ring come out of the cylinder, and leak fluid.
Reply With Quote
  #9  
Old 03-05-2017, 03:32 PM
N941WR's Avatar
N941WR N941WR is offline
 
Join Date: Jan 2005
Location: SC
Posts: 10,666
Default

You didn't give any details about the auto fuel.

What octain did you try and did you test it for ethanol?
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
Reply With Quote
  #10  
Old 03-05-2017, 04:14 PM
N427EF N427EF is offline
 
Join Date: Oct 2005
Posts: 1,462
Default 2 different issues.

Although your 2 issues happened about the same time, it is not likely that either of those are related in any way.
Quote:
My latest attempt to run mogas in my Superior O-360 was not good.
I don't know anything about your history and "attempts" to run mogas.
It is quite simple to run mogas and it appears that I have company in fellow RV-10 pilot 9GT as well as many others. I run mogas 91E10 all year round and my experience is the same as 9GT's mentioned above.
However, careful attention was paid to fuel system installation and using mogas was not simply an "attempt" but a deliberate and carfully considered plan.

Mogas will do exactly what you describe if the fuel gets overheated, especially
during taxi when flow is minimal and nearly stagnant.
I see that you have a carbureted 0-360 and I would be surprised if you did not also have a "fuel cooker" gascolater mounted in the engine compartment.
Please tell us more about your installation and a little history with details on your "attempts" to use mogas
__________________
Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 400 plus hours
Over 2500 Gallons of E10 mogas burned
Don't believe everything you know.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 03:57 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.