Fuel system sealant

Discussion area for builders of Pietenpol aircraft, both beginners and experienced folks. Share ideas, ask questions and help build the Pietenpol community.
Post Reply
User avatar
KenBickers
Posts: 128
Joined: Tue Mar 07, 2017 7:00 pm

Fuel system sealant

Post by KenBickers »

Folks,

This is a pirep on fuel sealants. About 4 years ago, I had my fuel tank out and reinstalled it with EZ Turn Lubricant at each of the threaded joints. With winter temps, the Piet has been mostly sitting the past several months. As I began the condition inspection, I discovered slow weeping of 100LL at each of the threaded joints in the fuel system below the fuel tank. I've attached photos with the tell-tale blue dye at each joint.

After some sleuthing on the internet, I found mentions of this same problem. What I found is that, as the name suggests, EZ Turn is a lubricant. It is not a sealant. Loctite 565 or, if in a high temp environment, Loctite 567 is a preferred sealant to use (there are other products also mentioned).

It's kind of pain in the backside to dissemble all these bits, but I'll be doing that this weekend to get them good and clean to reinstall with Loctite 565. Hopefully that will work better for the future.

Cheers, Ken
Attachments
IMG_0498.jpg
IMG_0500.jpg
tom kreiner
Posts: 71
Joined: Sat Feb 25, 2017 9:49 am

Re: Fuel system sealant

Post by tom kreiner »

Several years ago we had a speaker from Loctite deliver a lunch and learn at our EAA chapter. (If any of you other guys in EAA chapters would like to do the same thing, Loctite reps always seem to be willing - and have a small budget - to put on a nice program like that.)

During the program we specifically asked about sealing fuel lines. Loctites recommended sealant is Loctite 567 which is filled with tiny Teflon particles and semi hardens, becoming what I’d term a Slightly stiff gel.

You simply coat the threads with a small bead on the male, screw it into the female and make it snug. It doesn’t have to be extremely tight. If you need to take the fittings apart they come apart with just a little bit of torque and they unscrew easily. No heating required.

I have since used it on hydraulic fittings, water fittings, and, yes, fuel fittings.
User avatar
KenBickers
Posts: 128
Joined: Tue Mar 07, 2017 7:00 pm

Re: Fuel system sealant

Post by KenBickers »

Tom,

Thanks for this information. It appears that over several years, the 100LL slowly dissolved enough of the EZ Turn to allow it to weep its way along the threads. Were it not for the blue dye in 100LL, I doubt I would ever know it was leaking.

My source tells me that Loctite 565 should work just as well as 567 in the cool air of the front cockpit. Maybe I'll pick up a package of the 567 and use that instead.

Cheers, Ken
tom kreiner
Posts: 71
Joined: Sat Feb 25, 2017 9:49 am

Re: Fuel system sealant

Post by tom kreiner »

Your sources ar probably giving you good info, as the 565 is for a lower ambient temp. For FWF, the 567 is recommended.

If I had to grab only 1 tube, I'd make it the 567, as it can be used it without question in both environments. I also keep a tube at the house, for plumbing fixtures, etc. LOL We are such GEEKS!
User avatar
taildrags
Posts: 637
Joined: Tue Mar 07, 2017 10:39 pm

Re: Fuel system sealant

Post by taildrags »

Ken; great info, since I am using EZ Turn on my threaded fuel fittings too. I'll keep an eye on those until the next time I feel like twisting myself into a pretzel again, when I might just get back down there under the fuel tank and pull my assembly of fuel fittings apart to clean them up and re-do with the Loctite product. Your pix show a ball shutoff valve exactly like mine, which also brings to mind that I've been wanting to rework my fuel shutoff because sometimes the ball valve doesn't close quite all the way and I end up with a tiny seep from the carb air box as the bowl overflows. We have pretty good diurnal shifts around here certain times of the year, in the range of 50 degrees, and that's when the problem occurs as the fuel expands in the heat of the day. I fabricated a metal 'horn' that I riveted to the handle of my shutoff valve to enable the Bowden cable to just make a 90 to approach the valve from the right side without making a 180 to approach the valve from the back like yours is. The geometry doesn't quite let the wire push as hard as I'd like on the valve handle to shove it to the stop readily. Yet another reason to take the assembly apart to rework it.

By the way, I do have to plan well ahead when I'm going to get down under the front, way up under there, as I approach 70 years of age and am not as bendable as I used to be. But I've found a pretty good way to speed up the process. Before I start working, I put a pop music station on the radio and just listen through a couple of songs when I'm ready to climb back out and -without fail- some kind of rap or hip-hop will come on and I can't wait to climb out of there and change the station ;o)

Oscar Zuniga
Medford, OR
Air Camper NX41CC, A75 power
User avatar
KenBickers
Posts: 128
Joined: Tue Mar 07, 2017 7:00 pm

Re: Fuel system sealant

Post by KenBickers »

Oscar,

I hear you about the pretzelling required to work under the front instrument panel. Still, I think I'll take my chances with a bit of country western. Egress by rap might lead to even worse damage than what I'm trying to fix.

Wish me luck, Ken
Post Reply