testing for air intrusion

[Ranchdweller]

This has probably been discussed before but i couldn't find a thread on it. I see a lot of people using clear return line to help narrow down the air leak. Would I be asking for trouble if I block off the return and put regulated air (5 to 10 PSI) in the schrader valve and checked the system with soapy water?

 

[Big Bart]

Never tried so no expert. 5psi should not be problematic. 10psi might create an issue because you are blocking it off.

 

[Ranchdweller]

Now I know why you don’t use compressed air to test for air intrusion. 1. It didn’t work. 2. It made my lift pump go bad. I replaced the return caps and lines using the Standard Products kit, then couldn’t get it to prime. Found the pump wasn’t working. The caps were all OE international gray, the hoses were cracked and brittle. Made me think ALL the hose needs replaced. It was getting dark by the time I got it running, so we will know in the morning if that fixed it and give it a good once over for leaks.

 

[Big Bart]

Now I know why you don’t use compressed air to test for air intrusion. 1. It didn’t work. 2. It made my lift pump go bad. I replaced the return caps and lines using the Standard Products kit, then couldn’t get it to prime. Found the pump wasn’t working. The caps were all OE international gray, the hoses were cracked and brittle. Made me think ALL the hose needs replaced. It was getting dark by the time I got it running, so we will know in the morning if that fixed it and give it a good once over for leaks.

What psi did you use?

So you replaced your fuel pump too?

 

[franklin2]

Air intrusion is air going from outside to inside the system. Pressure testing would force air inside the system to outside. Might make a difference and cover up a problem.

 

[Ranchdweller]

Between 5 and 10 psi. My thinking was if air could get in, it could get out. I still think it could work 90% of the time. But everything would have to be blocked off. In my search for knowledge, I came across a bulletin from ford that said to block off one end and use a hand vacuum pump on the other. However, if you have a leak, you have to test smaller and smaller sections of the entire system until you find the leak.

 

[Cubey]

Between 5 and 10 psi. My thinking was if air could get in, it could get out. I still think it could work 90% of the time. But everything would have to be blocked off. In my search for knowledge, I came across a bulletin from ford that said to block off one end and use a hand vacuum pump on the other. However, if you have a leak, you have to test smaller and smaller sections of the entire system until you find the leak.

Was the engine cold? If so, you didn't account for the engine heating everything up. After driving it, rubber bits get more flexible and may let air in after driving. Maybe it eventually shrinks back sealed after a few yours, after air has already gotten in.

 

[IDIBRONCO]

All in all, I just don't feel like using air pressure to try to find an air leak is a good idea. Reading all of this just reinforces that feeling. It may work just fine, but I do feel like the vacuum method mentioned in the Ford bulletin would be a much better method.

 

[Big Bart]

Well it was worth a try, now you know.

Is everything working now?

 

[Ranchdweller]

Yes! Everything is working normally. Starts every morning like it should. I guess the true test would be to let it sit for a few days and try it again.

On to the other (less pressing) issues! Such as Fuel Selection Valve and fuel gauge not working.

 

[franklin2]

If you want to really test it, park it nose up for a few days. That is a lot of fuel hanging up in those lines just wanting to roll back into the return on the tank.

 

[Cubey]

If you want to really test it, park it nose up for a few days. That is a lot of fuel hanging up in those lines just wanting to roll back into the return on the tank.

Mine has that problem at times but the electric fuel pump seems to compensate for it. The last couple places I camped, I had no choice but to park nose uphill. The first was one night, and it took giving it some throttle and only a few short runs of the starter to get it going. It smoked a bit and idled unevenly until it smoothed out. Second time was after a week, same thing. I made sure to park nose downhill here I am now so I don't have to strain things when I leave after 7-10 days.

 

[Big Bart]

Yes! Everything is working normally. Starts every morning like it should. I guess the true test would be to let it sit for a few days and try it again.

On to the other (less pressing) issues! Such as Fuel Selection Valve and fuel gauge not working.

I think may of us are are stuck on one tank and no gauge. If my odometer (Current fuel gauge) breaks I am really screwed!

I have the valve but more pressing projects to do.