8450 question

[Andy P]

Small pressure line on intercool has T at intercool,one side goes to aneroid on fuel pump. The other side goes to T between top of fuel tank crossover vent line, I would think to pressure vent fuel tanks a little. Can anyone give me more info on this line and possible updates as 8430 and 8440 did not have this setup. Original line was quarter inch. plastic hose running through rubber hose. Problem is plastic hose melted inside rubber hose next to oil cooler. JD dealer doesn"t seem to know too much , finally found replacement line but its a foot and half too long. And very similar plastic line that goes from hydraulic pump and transmission on two wheel drive JDs. If anyone knows any history and possible updates on this line could you enlighten me? Thanks.

 

[rexhellwig]

I think you already have it figured out.

I'm guessing they sold you an AR79711 line? The reason this looks like a pump bleed line from a row-crop tractor is because that is exactly what it is. The original hose you took off has not been available in many years. The replacement should work fine. Its job is to SLIGHTLY pressurize the fuel tanks and help out the lift pump.

In the tee you described, there should be some sort of restriction between the manifold and the tank - an orifice, a specially drilled fitting, or a washer with a tiny hole. The restriction is usually protected from plugging with a small felt filter. Don't lose any of this stuff. Even though the tanks are steel, it isn't a real good idea to give them or the crossover hoses a full 25 psi manifold pressurization. It only takes a couple psi to raise the fuel to the engine.

If I understand correctly, this cap is slightly vented.