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  #41  
Old 10-11-2011, 07:08 AM
jthocker's Avatar
jthocker jthocker is offline
 
Join Date: Jan 2005
Location: Cincinnati, Ohio
Posts: 1,060
Default Fuel lube, EZ turn

Quote:
Originally Posted by prkaye View Post
So I spent some time yesterday tracking this down.
With the engine off, I started the boost pump and fairly quickly got a whiff of gas. So I started checking fittings.
I found a leak through the pipe-thread on the elbow fitting that penetrates the firewall into the gascolator. Gas seeped out through the tapered pipe thread when the fuel pump was on (this is the first fitting downstream of the fuel pump, so probably a fair bit of pressure there). I could actually tell that the carpet underneath that fitting had been getting gas on it.
I replaced the elbow and put Loctite 567 Thread Sealant on the threads this time (i had previously just used fuel lube). Waiting a couple of days for the sealant to cure and then I'll pressurize the system and check again.
I HATE TAPERED PIPE THREADS!!!
It's been my experience in the past, that every time I used Fuelube/EZ turn for a thread sealant, that fitting eventually leaked!!!!! I now use anything that says "thread sealant" on the tube for my pipe threads. I think I use loctite 561 with good success.
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  #42  
Old 10-11-2011, 07:17 AM
prkaye prkaye is offline
 
Join Date: Jun 2006
Location: Ottawa, Ontario, Canada
Posts: 2,116
Default

Quote:
that every time I used Fuelube/EZ turn for a thread sealant, that fitting eventually leaked!
Ok, yes, this has been extensively discussed earlier in this thread and in many others. As I wrote in my final post on this thread a few weeks ago, I solved the leaky pipe thread problem using Loctite 567.
Today's post is an update and a question - I am now getting only whiffs (only noticeable with auto gas), and I only seem to get the whiffs in a climb (no smell in cruise at any power setting). I suspect that this suggests a venting issue - am looking for validation of this suspicion.
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Last edited by prkaye : 10-11-2011 at 07:26 AM.
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  #43  
Old 10-11-2011, 07:45 AM
Tom Martin Tom Martin is offline
 
Join Date: Jan 2005
Location: Ontario, Canada
Posts: 1,544
Default

Phil
It is possible, as you suggest, that you are getting vent fumes into the cockpit at climb angles. Is it the same at full fuel vs lower fuel levels?
Also what about directing the vent outlets and away from the cockpit area to test that theory. If you do this you should experiment the technique with one tank first to make sure that the tank is still properly venting.
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Tom Martin RV1 pilot 4.6hours!
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EVO F1 Rocket 1000 hours,
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  #44  
Old 10-11-2011, 04:06 PM
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Mark Burns Mark Burns is offline
 
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Location: Ruston, Louisiana
Posts: 879
Default Maybe ??

See post #31
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  #45  
Old 10-11-2011, 04:55 PM
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jbagley jbagley is offline
 
Join Date: Sep 2009
Location: Aloha, or
Posts: 282
Default

Symptoms are exactly the same as my recent bout with a fuel leak. Fuel smell in the cockpit at low airspeeds and low power settings. I was told that the vent tube is the likely cause...

Turned out to be a fuel leak at the wing root, tank end rib. Wasn't leaking enough to make fuel stains, but at low power settings and low airspeeds the fuel vapor would find it's way into the cockpit. I did finally find some fuel stain near the vent tube fitting on the tank itself reinforcing the false belief that the vent system is at fault. Pressurizing the tank with over half a tank of fuel revealed a leak coming from behind the tank support bracket. I don't know what the tank is pressurized to in flight by the vent system, but it didn't take much for the tank to start leaking on the ground (it wouldn't leak otherwise); really just closing off all the fittings and squeezing the tank by hand was sufficient. Talcum powder is a great idea and wish i'd thought of it when I was trying to find the leak.

I removed and repaired the tank last week. Flew it for the first time since the repair today. No fuel smell.
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  #46  
Old 10-12-2011, 07:18 AM
prkaye prkaye is offline
 
Join Date: Jun 2006
Location: Ottawa, Ontario, Canada
Posts: 2,116
Default

Quote:
See post #31
Hmmm... what I was trying to explain (unclearly it seems) in my recent update post yesterday is that my symptoms are DIFFERENT now after my fix of the one seeping fitting. Now the smell is much weaker, and it's not low power settings that triggers it now - these new wiffs now seem to occur at low airspeeds. I get them in a climb (at high power), and a little bit when taxiing or idling (low power). In cruise I don't get the whiffs.
Suspecting either venting, or a subtle leak on the inboard end of the fuel tank(s) as in the case of the previous post (although I had the fairings off recently and found no obvious leaks there). In cruise, it seems whatever it is gets blown away unnoticed. The hunt continues. At least now it's only occasional mild whiffs.
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