Fuel System Connections

[Rockfish]

There was considerable discussion in a recent thread on which method was best for sealing metal fuel fittings on Al marine gas tanks, cut off valves etc. Basically the liquid sealant method vrs fuel rated thread tape.

As a result of that discussion I have decided to switch to the liquid method and had a product recommended that comes in a hand squeeze tube called Permatex Form-A-Gasket Sealant. Apparently this is what a local shipyards uses. When I went to buy it, I found there are two types called (not surprisingly) Permatex 1 and Permatex 2. Both types are gasoline resistant.

Permatex 1. is fast drying and hard setting for sealing rigid materials and flanges.

Permatex 2. is slow drying and non-hardening for sealing flexible assemblies.

All the screw together fittings I have acquired are Al fittings to prevent dissimilar metal issues with the Al tank. So my question is, which would be best for rigid metal to metal Al fittings. Logic would suggest Permatex 1. However, I don’t want these fittings permanently bonded together as at some point in the future I may need to unscrew them and take them apart to say clean out an internal tank pick up tube for example.

So if I use Permatext 1, will I still be able to get them apart or would Permatex 2 be a better choice ???

Even if I use Permatext 1 on the hard fittings would it be a good idea to use 2 on soft connections such as where a fuel hose clamps to a metal fitting or is it best to use high end marine type hose clamps only??? There are some cases where I may need to remove a hose and put it back such as the filler hose, without cutting off the hose making it too short. On the other hand for actual fuel lines I usually just cut them off if its easier as they should be replaced periodically anyway and are a lot cheaper than the very high end filler hose that should last decades and is a ***** to install.

So what do the experienced/mechanic types recommend???

 

[Wild Bill]

Well only 40 years experience however threaded fittings I would use something like this.
https://www.permatex.com/products/t...d-sealants/permatex-thread-sealant-with-ptfe/

 

[Rockfish]

Thanks Wild Bill I understand you have done a lot of Mechanics, Midway had the two types of Permatex I got but not the thread type. Did not know it existed and perhaps I misunderstood the type of Permatex they were recommending. Interesting that on the two types I have, the say it is resistant to gasoline but on the thread type they say oil and diesel but omit gasoline. I assume you have used the thread type for gas fittings without issues. I worry a little that the sealant not dissolve into gas and cause problems with the motors/filters.

 

[Wild Bill]

Are these national pipe thread fittings? I was told by a locktite engineer pipe sealant is mostly a lubricant so you can get the fittings tight enough to seal, male NPT fittings are smaller at one end and bigger at the other. Not sure what brand we stocked however never had an issue. Anaerobic sealants work well,also.

Looking at the specs and since you already have it I would probably use No. 2. Use it sparingly so you don't get any in the system.

 

[bones]

Use just enough to coat the threads, its all you need. Any more will just take longer to to clean off next time. Guy that used the thread seal on my stats used to much and by the time I got it off the plastic nut didnt look so good. Then there was all the scratching off the old stuff

 

[triplenickel]

Like you were thinking #1 will make for awful dissaasmbly. Use #2.