How to fix this crack

[Mysfyt]

Here is what I would do: Remove the tank, drain it, flush it with solvent such as mineral spirits, flush it again with water, then let it sit in the sun with an air hose blowing on the inside to dry it out. Then I would purge it with a backing gas such as argon, grind the old welds off and take a cutter wheel and follow the crack to vee it out. Tig weld it with 309 rod and then pressure test with air and soapy water. Be careful with the air pressure that you don't explode the tank. Only takes a few PSI.

Reinstall the tank with an oil resistant neoprene pad or vibration isolators so the tank isn't getting stressed by the chassis.

Some are going to say this is over kill, but I'm speaking from a LOT of experience fixing tank leaks.

 

[Egon]

From the picture the tank seems to be an integral part of the frame. Mysfyt; like the method of weld prep for the tank.

Seeing that there seem to be high stress points would exterior beefing up of the frame other than fish plates be advisable? Something like adding Chanel or angle top and bottom on both sides?

 

[IslandTractor]

Powertrac must have dealt with this type of cracking before. What do they recommend?

I've never had to fix a crack in a tank that is structural but I think I favor Mystyt's thorough approach. Maybe some bondo/jbweld until the mowing season ends and then fix the tank properly as a winter project????

 

[jack707]

Well you could use job weld! and you won't have to worry about the oil blowing up!!!

 

[Gary Fowler]

I have fixed a lot of leaking oil (diesel) tanks in oil refineries and the recommended way is to have liquid covering the weld area and circulation of the liquid to keep the hot liquid distributed. For such a small repair, the heat input isn't going to be that bad if you let it cool between passes.
Hydraulic oil is not explosive although it will burn. Be sure to keep the tank vented so that any pressure buildup can be dispersed.
Another way to do it would be to keep the liquid level well below the weld area but fill the vapor area with inert gas like argon or CO2. I think this would be my way since welding over oil is pretty hard to get a good weld which likely has something to do with the crappy weld on it now.

Clean the weld area up by removing all the old weld, slightly Vee the cracked area but not so much that you will burn thru the tank when welding. Wipe it down good with a solvent like Acetone to remove all the oil residue and allow to dry. Then weld up the cracked area so the weld is just slightly above flush then grind it flush. Put on a reinforcement plate on top and side to handle the stresses better. A 6"+long piece of 2x2x1/4" angle iron laid in a horizontal direction over the top so one leg is facing down the side would give good strength to the joint. I would do the same thing to the other side with the angle iron reinforcement prior to it breaking. Round the end corners of the angle iron and weld it all the way around with a 1/4" fillet weld using the welder of your choice. I would use 7018 since I don't have wire feed welder but a MIG would work well also as long as you keep all the oil away from it.

 

[truckdiagnostics]

Powertrac must have dealt with this type of cracking before. What do they recommend?

I've never had to fix a crack in a tank that is structural but I think I favor Mystyt's thorough approach. Maybe some bondo/jbweld until the mowing season ends and then fix the tank properly as a winter project????

run it till winter then fix it right. When i looked at it the tank did look integral, so coming up with way to flush before you weld on it is going to take some thought. You may have to go as far as to cut large hole in the bottom with a hole saw, then come back and weld in drain plug. Do not weld on that tank unless it is cleaned out and purged! It is amazing, how little it take in a takes left in a tank to make it pop. Like mysfit said you might be able to put positive pressure in take with gas like argon or nitrogen. I have heard of guys flowing car exhaust through the tank when welding also. If I was doing it we would pressure with nitrogen, as that is what we use to positive pressure HVAC lines before brazing. It is going to take sometime to do it right.

 

[jwmorris]

Back gas the inside with an inert gas will keep you safe and put a plate on top and oval/diamond shaped ends would be best or if you use a rectangle just don't weld the ends, only the sides.

 

[dickfoster]

So I have had this crack in my tractor since I bought it. After a couple of years I took it to a machine shop, they slapped a weld on it and within a year or so it cracked again.

This crack is over top of the corner of the oil tank, and goes into the engine tub. When I am on steep slopes, oil will weep out.

Not completely sure why / how this crack formed, its in an odd area. Probably a bad weld which happens with my type of machine now and then.

So, when I took it to the machine shop to weld, they guy popped the top of the oil tank and welded away, saying there was no issue, it would be very hard to catch the oil onfire.

Now I am going to probably attempt the repair myself. I have some 2" angle iron that I think is 3/8" thick. I am going to just weld it down overtop of the crack (doing it to both sides and for a distance for rigidity). I will, of course, grind down the old weld and apply a new weld underneath.

My questions are this:

Is there a better repair you guys can think of. There is stress in this area, typical tractor flex.

Can I do this weld with the oil tank full (it is not at the top, it is around 3" down). I do not want ot drain the tank as I am afraid of more contamination in the oil, as well, it may make the whole situation more flamable.

Should I drill relief holes (If I do, then I am probably going to have to drain the oil due to contamination falling in the tank).

So basically, how would you experts do this?

I'm no welding expert by any stretch but even my buggerfied welding is better than that garbage. What did he use, a car battery and coat hanger wire? LOL

 

[MossRoad]

MossRoad great ideas! For the fish plates I would not use 90-degree corners! The frame is already stressed. I would use large ovals. In this situation stress riser will be a huge problem!

I can't draw ovals! :laughing:

 

[MossRoad]

On Power Trac machines...

The hydraulic tank is integral. Its part of the frame and tub of the machine. There are also usually drain plugs built into the hydraulic tanks. It would be a simple (yeah, right, nothing's simple) matter of:
- Drain the hydraulic oil into clean containers for re-use.
- Disconnect and plug all of the hydraulic hoses that run to that tank.
- Fill the tank with some other liquid that's not flammable.
- Clean, prep and weld the cracks.
- Add the fishplates.
- Drain, clean and dry (maybe flush, too) the tank with kerosene, maybe?
- Reconnect all the hoses and put the fluid back in....

Yeah, simple! :laughing:

Anyhow, that's all guessing, as I've never done it before.