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timjet

Guru
Joined
Apr 9, 2009
Messages
1,920
Hey guys, whats the best sealant to use on thread fittings used for diesel fuel.*

Also hows the best way to attach a fitting if it needs to be in a certain position but the threads aren't tight enough. I have a squeeze bulb priming system and I need the fitting to point in a certain direction. When tight they are not in the right direction. What to do??
 
There is YELLOW teflon that is fuel rated.

To use teflon do not cover the first 2 threads , otherwise bits can come loose.

Unskilled folks will prefer tefflon paste.
 
I like Permatex #2, the kind that never gets hard. To point a fitting exactly where you want it you'll need to use some sort of compression fitting. IMHO Swagelock makes the best out there; they use them on the space shuttle and other aerospace. http://www.swagelok.com/products/fittings.aspx

They should have a local distributor.
 
Here at work we use Loctite 242. We assemble thousands of fittings every day and they don't leak. The fitting only has to be snug and the loctite seals it. You don't need much, just a thin bead about 3/4 of the way around the fitting.

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I built my entire fuel filter and polishing rig with Permatex Blue and it's working great. Even the fittings I could not get fully tight. With no more pressure than it sounds like you will run, it will do fine (and you can get it anywhere).
 
Also hows the best way to attach a fitting if it needs to be in a certain position but the threads aren't tight enough. I have a squeeze bulb priming system and I need the fitting to point in a certain direction. When tight they are not in the right direction. What to do??

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I have run into this and one way is to use JIC hydraulic fittings.* A straight adapter with a male jic taper on one end and a pipe thread on the other.* The pipe thread screws into the port you have.

Then an elbow with* with a swivel female jic end on it and a female pipe thread on the other.* The two jic will align in any direction you want and when tightened are leakproof and will not loosen.** Then you can use any pipe thread hose end you want in the other end of the elbow.

Examples:***** http://www.fairviewfittings.com/techdata.html?id=64235
http://www.fairviewfittings.com/techdata.html?id=64042

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Take a look at the two link I've shown to see how they work together and figure out the sizes you need..** Most hydraulic fitings mfgrs. will offer these. There are many other combinations allthough*it will take a lot of looking.* If you*have a hydraulic supply house nearby they should be able to help particularily if you print out the photos.**

*i didn't look but they may be available from someone like McMaster Carr.
 
teflon tape is never a good idea on fuel systems I dont care what you do , pieces still find there way into the system
 
What I ended up doing is using a paste sealant, I think it was Rector, but made especially for fuel connections. I was modifing a squeeze bulb priming system and did not want to spend the money for the swival hydraulic type connections. On two connections they are just barely hand tight and do not leak. I will observe them frequently to make sure they don't leak, however the only time fuel flows past these connections is when I reposition the valves to allow fuel to go through the squeeze bulb. So not much to worry about even if they did leak a little during the very rare time I use the squeeze bulb.
 
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