John Deere 620 tractor leaking gas cap

Farmer MM

Member
The vent in the gas cap allows gas to travel up vent, out the lower plates, and on to side of the tractor, when operating on rough terrain. It's a newer gas cap, and I added another gasket to be safe. Some people said JB Weld the breather hole, but that could cause negative tank pressure, with bad results. Is there a NON-leaking replacement JD gas cap?
 
Well you need to FIX the gas tank vent system. The hole in the cap is to let air INTO the tank not fumes/fuel out. On the front of the gas tank filler neck is a fitting that a line is supposed to be hooked to that then goes over the front of the tank then it connects to another line that goes down to under the frame rails. Look on page 35-4 in the JD parts book PC0528. Look at items 17 and 18 these lines are the vent lines for the fuel tank. (This is the standard tank but all fuel tanks have a similar setup)

I will bet yours are not working. Many of them get plugged up with dirt/rust. Even more get took off or crimped shut by some one that has ZERO idea of what they do. FIX this ASAP!!!! This is not just an issue because of ruining your paint job. I personally know a fellow that darn near burnt to death on an IH tractor that was leaking like your talking about. That gas running down the side of the tank can ignite on the exhaust or the distributor. Then you will be the first guest at driving your tractor while on fire party!!!

P.S. Does anyone know how to copy the darn PDF files the old JD parts books are in??? I can copy the page on the new books but not the PDF ones.
 
THANK YOU all for the info! I just finished plowing 40ac, and it worried me the whole damn time! It'll be fixed this weekend!
 
I had a 620 with the same problem. Kent Kaster with K&K tractor sold me a non vented cap that fixed the problem. I saw him at Portland In. and told him about my problem and I did what he suggested and it worked.
 

On the gas tank vent tube...I blow compressed air in to the end pipe, but I don't hear anything coming out in the gas tank. Should there be a noticeable air discharge, or is there a one-way flap/seat in there? I also found the original gas cap buried in the junk-box, and it is NON-vented. I'm concerned about simply reusing it, as the tractor used to starve-run out of fuel, after using it for a period. Obviously, it is lacking air-venting.
 

It's FIXED!!! I pulled the copper tube off (fits over the smaller tube attached to gas tank breather), and behind it, on the bottom, there were 3 holes (from hitting the fan-belt pulley), and PLUGGED with dirt/grease! Cut the lower piece off, put on a long gas-hose, and NOW the air blasts in to the gas tank!

Thank you all for your insight!

F-MM
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top