Brazing a hydraulic oil tank

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I'm a long time lurker but first time poster and I need some advice. A few years ago my son and I built a log splitter and used 8" square tube as both the axle and the oil tank. The splitter works well with one exception. We put the intake for the oil in the center of the back side of the tube. At certain angles the pump sucks air because the fluid level drops. It's gotten to be real aggravating. I want to move the intake to the bottom of the tube so that it will always have oil but I no longer have a welder or money to buy one. I do have a small Mapp gas/oxygen kit and thought about brazing a steel elbow (cast iron?) to the bottom. There would be no pressure on the fitting. I guess my concern is the flash point of the oil. I talked with a local welder who thought it would be safe to weld it. I don't really have a way to get the splitter to the welder and brazing will suit my purposes. Will I be safe enough to drain the tank and go at it? What do you folks think I should do? Thanks for any advice.
Reply:You can braze it, but..... Clean out all the oil.  Its the white vapor that catches on fire and goes BOOM!The tank needs to be vented well, so unhook all lines and remove any thing you can to vent it.  You can also purge it with Co2.  A continous flow in the tank escaping out the vents or ports will help.No matter what clean out the oil as best as you can with soap and water or take the tank to the car wash and stick the wand in it on soap.You could fill it with water up to just below where you have to weld.  This limits the amount of oil and white smoke it will hold.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Mine is built the same way..I have figured out that it has to be level..And I run it a little over full at all times..If it's tilted sideways the fluid just pours out the vent hole..It should be level at all times anyway..Much safer that way.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Thanks guys. When we built it my thinking was that if I ever had to move over the road I wouldn't want something snagging the fitting. What happens though is when it begins pumping through the lines the level drops just enough to require it to be level. If I fill it more it just blows out the vent hole like Zapster said. I should have given it more thought originally. It was one of our first father/son welding projects and in the merantime my welder broke so I'm down to brazing now. I'm thinking I could somehow tack it on enough to hold it in place and then use JB weld to seal the opening. Or just use it like it is.
Reply:Put an extension on your vent to raise it up and add more oil.Tim Beeker.
Reply:Can you raise the vent? Put a combo vent/reservoir chamber up higher?  Putting a tube on as the vent helps get 95% fill but you'll get a little burp every now and then. Wouldn't take much for the cubic inches to add up. Cubic inches equal reserve.
Reply:Now that's a good plan. The vent is also the filler though and that will present a problem. If I can I'll try to post a photo to show you what I'm facing. I live on pretty uneven ground so it's difficult for the splitter to be level all the time. What we've been doing is placing it so the back end is downhill and that keeps the fluid level up. It's just a shame because the splitter is exellent otherwise. My son did the welding and did a great job. It was really one of the first things he ever welded. He has a knack for it.
Reply:I just thought it might be easier and longer term to find a little room for extra reserve and plumb it through the top or vent. A 6"x6"x8" box would be over a gallon.
Reply:Suppose you drill and tap a hole in the bottom of the tank, (keeping it as small as possible for the size fitting used, so it won't screw in way to far [assuming tapered threads]) and attach the input that way? Is the tube thick enough for that? Maybe use a pair of 90* bends so your hose still comes from the back or side and won't snag.I like the idea of just  adding a higher surge tank and await pictures to see how that might be done; also, we all just need to see the splitter for its own sake! BTW, what part of the world do you live in and what kind/size wood do you have to split?What kind of welder is it that broke, what is wrong with it, and what is needed to fix it? Any advice needed on that??Last edited by Oldiron2; 07-13-2008 at 01:05 PM.Reason: Added sentence
Reply:Originally Posted by hvw...I want to move the intake to the bottom of the tube so that it will always have oil...
Reply:I like the extra tank idea also. I have room for it on top. I'd have to figure out the best way to attach it. It'd almost have to be mechanical though as I'm minus a welder. This splitter  was originally a three point type sold at Northern tools. Somebody had stripped it of everything but the beam, cylinder and 3 point attachment so I bought it as scrap and rebuilt it as a traditional type with it's own engine but left the 3 point attachment so I could also carry it around on a tractor or tow it behind a truck.. I live in the hilly part of middle Georgia. We cut oak mostly for  firewood. The splitter has a 4x24 prince cylinder so we split 22-24 inch lengths. I have split wood, including sweet gum, as thick as 30 inches in diameter with it. It will bust anything I'm man enough to put on it. I used a 6.5hp engine with a two stage pump and a Prince control valve. I probably could have bought a new one for a couple hundred more dollars but that's not the point. We enjoyed making it! Thanks for all the suggestions. They've pointed me in the right direction.
Reply:Good, hope it works out, let us know.Beware of  "swimmers" after working on a hydraulic system reservoir, especially  if the suction line is not filtered. Metal chips, slag, etc. will tear a pump up fast.Good Luck
Reply:That is why any hydraulic tank should be made with some sort of suction strainer in the tank even if a spin on filter is used. Without a strainer the fluid can make a vortex and suck air even if the fluid level remains somewhat above the pick up bung. Likewise the tank should have at least one baffle in it. The baffle keeps the hot oil from going straight back to the pump before it mixes with the rest of the fluid and cools. The baffle allows the junk in the oil to settle to the bottom of the tank instead of getting circulated with the oil.Now a strainer won't cure your problem but it still a very imporant part of the system. Adding volume will help but this type splitter/tank will always have to somewhat level. i would thionk about adding a swinging trailer jack so the splitter could be made level no matter where you might have to use it.Last edited by tresi; 07-13-2008 at 05:22 PM.
Reply:The tank on this splitter is about four feet long. It has the return on one end with a spin on filter ahead of that, the intake also has a good interior filter. I put in two because I was worried about rust inside the tank.  I didn't put in any baffles. One of my concerns about moving the intake is having to eliminate that filter without doing some major modifcations. I've learned now that with a tank of this type the splitter will always work better while fairly level. I got a lot of great suggestions to think any of which would solve the problem. It's plain from reading the responses that like most things there is a lot to consider before you build something like this. We were kinda like cub bears playing with our you-know-whats when we did it.
Reply:That great that you put a suction strainer in that narrow of a tank. I wouldn't worry about not having a baffle if you have the return and suction near opposite ends of the tank. Another thing you can do is make the return a pipe that extends close to the bottom of the tank so that the returning oil doesn't splash into the tank and cause a great deal of foamy oil in the tank.
Reply:if you 're going to add a tank,just stop using the original . i used a freon tank for mine. it's 2 1/2 or 3 gallons.