John Deere 820 (3 Cylinder Diesel) Fuel Leak

[TurnerJR]

I restored by Dad's 1970 model John Deere 820 (3 Cylinder Diesel) tractor. I am 60 years old now and I drove it brand new right after they unloaded it when I was 10 years old. It was the worse for wear after my Dad passed away in 2008 but, I brought it back to life and use it every time I am at the farm. It has become a Texas-Sized riding lawnmower with the addition of a finishing mower.




It runs great but, I am having one persistent issue I can't seem to fix. It had been leaking diesel under the tank near the fuel shutoff valve for some time. It has a fiberglass fuel tank and I tried a couple of times to fix it to no avail. I finally broke down and bought a new tank (they like that thing--it cost $500), new fuel gauge sending unit and gasket, new fuel valve, new drain valve, and new fuel connection hose. I installed everything properly including putting Teflon tape around the valves when I screwed them into the tank. Unfortunately, even after literally replacing everything, I still have a very slight leak, enough to drip on the floor of the barn and create a mess. I have an old fuel cap I am planning to make into a tester so I can pressurize the tank and use soap to see where the leak is coming from.

I think all the John Deere tractors of this vintage with fiberglass tanks had a leaking problem. Does anyone have a similar experience with a John Deere tractor of the same vintage with a fiberglass tank? They could be found on 820s, 1020s, 1520s, and 2020s of some model years and perhaps even the later 830, 1030, 1530, and 2030 models as well. I'm about to pull my hair out in frustration trying to fix that darn leak!

 

[beenthere]

:welcome: to TBN

Hope you have an idea how little psi that tank can take... without exploding. I don't, but maybe you or others know better.

I'd just go back and re-do the fittings.. and hope they haven't been over-tightened and caused a crack.

Beautiful restoration job. That really looks good, and understand your frustration with the fuel leak.

 

[Peter 315]

Very nice tractor.... If its all clean under the fuel tank and you spray foot powder the canned stuff it goes on white and will turn dark when the fuel touches it ,You should be able to find the leak then..........

 

[Tx Jim]

Very nice looking 820 I sold JD 820 utility tractors when they were brand new. I sure thought they had a metal fuel tank.

 

[Zebrafive]

Not any help, my 2030 has a metal tank, my worry is rust. I had to replace the tank on my ford F250 a little over 20 years ago.

 

[TurnerJR]

It seems the John Deere 820 and 1020 were almost the exact same bill-of-material. The main differences were the injector pump and injectors. The 1020 is rated for a few more horsepower. Another difference is a metal vs. a fiberglass fuel tank. The 820 was manufactured in Manheim, Germany while I believe the 1020 was manufactured in Dubuque, Iowa. You're right that it would be important not to blow up a fiberglass tank by pressurizing it. My intention is to pressurize it only slightly--perhaps 1-2 PSI--with air and do a soap check for leaks. My current thinking is the leak is coming from between the metal fitting embedded in the fiberglass at the bottom of the tank. If that's the case, it will be relatively easy to seal from the exterior. The metal tanks are even more expensive than the fiberglass tanks. But, in retrospect, I wish I had gone for a metal tank when I replaced mine in lieu of going back with a fiberglass one.

 

[TurnerJR]

I have looked at the illustrated parts catalogue for both the 1020 and 820 in detail. The 1020 was rated for about 38 PTO horsepower while the 820 was rated for about 31. The injectors and injector pump appear to be potentially the only differences. Mine has a Roosa master injection pump. I changed out the injectors when I restored it and the new ones now are listed as the same P/N for both the 1020 and 820--so, I may have souped-up my 820! Do you know of the differences between the 820 and 1020?

 

[TurnerJR]

I wish I had gone back with a metal tank in lieu of another fiberglass. Oh well, hindsight is 20-20!

 

[TurnerJR]

I can give that a try. I'm determined I'm going to find and fix that leak. The darn thing has probably leaked for 20 years!

 

[TurnerJR]

Somewhere I read it is possible to screw the fittings in too far. They bottom out in the boss on the tank but, perhaps I should stop half-way. I assumed they were like pipe threads but, perhaps not.