I have a 1995 case 580 sk, and I think I have the infamous "crack" type leak. I have the leak pretty much tracked down to a spot under the "drivers" side of the cab, right behind the step where you step to get in the cab. I will most likely be selling the backhoe next spring and upgrading to a newer used one, but I would like to sell it in as good of condition as I can make it. I dont want to take it to a dealer, and I was thinking maybe I could lift the one corner of the cab, and maybe weld the spot (I would drain the tank, wash it with soap and water and make damn sure there were no fumes) or possibley JB weld it, or something along those lines. Anyone ever fix this problem, without actually having to take the cab off, or splitting the backhoe?
Depending on the position of the crack - I've cut out a piece of the floor with a grinder, carried out the repair, tested it over a couple of days & then welded the cut out floor piece back in.
I have cracks on both the fuel tank and the hydraulic tank. I drained the hyd below the level of the crack and tried JB weld the first itme and a fiberglass fuel tank repair kit the next and neither worked. I had to weld a crack around the pin boss that runs through the top of the fuel tank. Talked to a dealer about the possibility of exploding. They said not to worry, they have welded fuel tanks with burning fuel spitting out like a flame thrower- "Just keep welding" was the advice. For what it's worth, An old guy told me he used to weld gas tanks by putting a hose on the tailpipe of his truck and fedding it into the tank. Evidently replacing the air in the tank with exhaust keeps the fumes from igniting. I've never tried it but it probably wouldn't hurt.
I have repaired alot of these cracks on the fuel and hydraulic tanks of the K series. The best thing I have found is once you have removed whatever to gain access is to put a vacumn pump or shop vac on the tank and weld it while it is full. The vacumn will keep the fluid pulled out of the crack so it welds good. Some times the tank vents have to be plugged to get the tank sealed up to hold a good vacumn. One of the most comman spots for leaks is the seam above the rear engine mounts on both sides.
I have been taught that a fire needs two things, fuel and oxygen. If you remove either of these you will not have any risk of an explosion. As I see it, pumping in exhaust is the easiest way to go to eliminate the oxygen and your hazard. I have used the exhaust trick a few times.
The K was famous for this failure. The L had most of the problems that caused it redesigned. I had the same problem 2 or 3 times when I had a 580 super K. If you use the loader a lot in hard conditions, or if you run a breaker, vibra plate, or in my case it was a compaction wheel. Puth te wheel down, and stand it on the bucket to get as much weight on the wheel as you could to get compaction. We had to pull the engine out to get to all the crack one time. The second time we caught it before it was so bad. JB weld will stop the leak, but only untill it gets used and makes the cracked area flex. then it leaks again. Depending on where it has run to, you may not reach all of it by going in the cab route. I had an open cab machine, so it was a little different. Been 12 years ago, so my memory is a little foggy on the details, but we reinforced the problem area and it lasted untill we sold it a few of hard years later. If you upgrade, get a 580 super L and you wil be happy. They are pretty cheap now, and you can still find some that are not used up. As I said, most of the weak points on the K were fixed on the L, like the frame, the loader arms, the diff, and the brakes. Those were all the problems I had with the K in over 7000 hours of hard use. It would still out dig a 10 year newer Cat hoe.
There is more to to the exhaust method than what you guys are telling - Before Somebody gets hurt The Tank is suppose to be empty , dry ,Rinsed out - then put exhaust to it - bring tank up to a temp. of not being able to leave your hand on tank- also no choke on - BEFORE YOU WELD The heat from exhaust is suppose to burn fumes from metal , the lack of o2 prevents explo.- I am not a fan of welding gas tanks Diesel tanks , I have welded both with and without fuel have never caught one on fire- But you can do a much better job ,a lot quicker if they are empty and steamed clean
Just to add, -make sure you prep (vee) out the crack to within a mm or two of the internal surface, if it's not a full penetration weld, you will probably have to reweld it again, and again. -Drill the ends of the crack with a 6mm drill. Do a root run first (with no porosity) and then subsequent runs to fill the vee. -As OneWelder mentioned, preheat the repair area to prevent hot short cracking (hot weld vs cold base material) -Use an appropriate, low hydrogen electrode Eutectic 6666 work well, 650 tensile strength, 20% elongation. I have welded hundreds of DIESEL tanks, as full as possible, purged with CO2gas, from a CO2 cylinder, without a problem. Although: Petrol tanks=empty/steam clean/co2 purge.
Thanks for all the replies fellas. Sounds like something I should really hire out to get done. Im a decent welder, but definately not a pro. I would also hate to blow myself up lol. For you guys that have welded with diesel in the tank, does the small diesel leak affect how well you can lay a bead down, or does it just burn the diesel up and lay a good bead? I was thinking of upgrading to at least a 2000ish model, and im not gonna be picky whether its a case, cat or JD, but thats still in the future yet!
make sure the diesel level is a few inches (6) below your weld area. Prep the crack (as above) and spray some contact cleaner (non-flammable) into the crack to clean any residue away. The diesel may bleed down onto your first root run of weld. If your weld shows porosity (small holes) just grind it back and reweld. The heat will evaporate any remaining residue. The co2 purge is important, if you aren't comfortable with doing this repair, you should probably get a professional to do it.