OzVMX Forum
Clubroom => Tech Talk => Topic started by: tony27 on November 16, 2011, 05:10:54 am
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My CZ tank has developed a weep along the front seam over the weekend, not 100% sure where exactly but the paint has lifted/dissolved in 1 spot
What's the best/cheapest/quickest option for repairing it before the Taupo round of the MrVMX series at the start of the month?
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Sounds like a steel tank?
Get somebody who nows what they'e doing [still alive] to oxy weld it.
I have oxy welded a few in my time without incident BUT you MUST de-fume the tank first.
DON'T do it yourself until you've seen somebody else do it properly.
Tanks that have seams like ridges [like steel gerry cans] that hold fuel residues are particularly hard to de-gas.
Once I did a 250 XL tank near the bottom edge but the material was subject to vibration I think 'cos after 2 tries it kept splitting so I had to bronze weld it instead to fix it.
cheers pancho
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Mate of mine [ still alive ] runs Argoshield through them while he welds them.
As I said he's still alive. ;D
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what about filling them with soapy water or sand........ and leave the cap off
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I have oxy welded a few in my time without incident BUT you MUST de-fume the tank first.
DON'T do it yourself until you've seen somebody else do it properly.
cheers pancho
Good advice from Pancho
I've done a few leaky petrol tanks by soldering or brazing after first washing them out with HOT soapy water then connecting them, through the filler aperture with a piece of suitable tubing or whatever , to an exhaust outlet of an idling over vehicle for about ten minutes or so , I'm still here as well, oh yeah, take the tap out to allow the exhaust fumes to pass through.
BE CAREFULL
Foss
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Or coat the inside with fuel tank liner compound. Have not used it myself yet, but folks with classic cars rave about this stuff.
Check Caswell, Blue Lightning, Kreem etc...
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PORS
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Yep steel tank, I think the front righthand seam above the mount is the culprit
Do you mean POR15 Freaky or is there another product?
Haven't ever used a tank liner before & until this problem it wasn't a consideration as the inside of the tank is clean & rustfree
Will look into what is available locally over the next few days
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dont forget after the soapy water and welding swill out with meths and leave to dry out
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Tony I have solder them before no problem, wash the tank 1st then blow the vac into for hour, have used POR15 before as well it works great kit is about $100 Resto Spares stock it locally.
Cheers
Tony
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If the tank does not need re painting then i would use RED-WHITE-BLUE tank liner kit. It will fix it for good. Would be a shame to weld and then have to repaint the tank if it did not need it.
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do not run petrol engine fumes through a tank! i had one explode. it has to be a diesel engine. runnings diesel fumes through a tank for a few hrs first is what they taught us at mechanic school 30 yrs ago.
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do not run petrol engine fumes through a tank! i had one explode. it has to be a diesel engine. runnings diesel fumes through a tank for a few hrs first is what they taught us at mechanic school 30 yrs ago.
You are right, Kenny,
I forgot to include that to my post, the length of time is a moot point as I have had no problems with shorter periods, however better safe than sorry !!!
Foss
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shite,diesel!!,geezas nobody told me! :o,i always left the car running with large hose into the tank whilst i welded,was more concerned with gassing self,than exploding tanks ::), :P
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I’m not a big fan of these liner kits. They can be great for fixing small holes but I feel they don’t offer any structural strength. So if the tank is splitting at the seams it may need the strength of a weld to keep it from cracking further.
The main reason I hate the likes of chemical liners is that it make it nigh impossible to weld afterwards as the liner material will keep trying to come up into the weld causing porosity in the weld.
There are some ‘chewing gum’ type fuel tank repair kits around that may be a good fix until you can find a welder brave enough, if the crack in the seam looks like it might need to be structurally repaired. I generally hate these too as they can be hard to get out of the little nooks and crannys before welding, but at least on the outside of the tank it can be done.
If soldering be aware that if you use a soldering iron that has a gas torch mounted behind it the gas torch may set off an explosion.
I’m not so sure about running engine fumes for hours before welding as the purpose of the fumes is to take away the oxygen which will stop any explosion. Run it long enough to completely fill the tank with fumes.
As for the petrol / diesel thing, it may be that if petrol engine is running rich then it will fill the tank with more combustible material.
Still alive, just,
A repeat post from somewhere else on here…
I have welded many alloy tanks over the years, without a problem, the alloy doesn’t seem to hold the fumes like steel tanks and as it doesn’t glow when welding it has no ignition source.
But steel tanks, that’s another story. I had welded a couple successfully by filling them with water but this can cause dramas too.
You can’t weld when the water backs onto the weld area as you can’t create a decent weld pool, so you need to leave a small air pocket in the weld zone. This worked okay a couple of times but then quite a few years back now I was asked to weld up a small crack in a seem of a stainless steel boat tank. No problem I thought. I filled it full of water, left a small air pocket behind the weld area & proceeded to weld.
I was kneeling down at the time, resting my elbow on the tank. I was doing okay and I just had to get the last little bit when wooooooooopppfh.. It seemed like the blast lifted me to my feet and knocked the welding shield off my head. My heartbeat was suddenly elevated to that of a 20-minute moto, although without the burning lungs.
I then had a very real fear of being electrocuted as the 40 litres of water from the tank gushed over the factory floor and headed for every extension lead. I had to quickly pick up the leads out of the way and then grab a broom to divert the water away from other machinery. Some guys from the factory next door came running in to see what the blast was. It didn’t seem that loud to me, I think I must have been in the epicentre.
And the tank, well it was completely rooted. It used to be rectangular but now all six sides were rounded and every seam had a crack in it.
I had to make a new one from scratch.
In hindsight, I realise now that what traces of fuel that was in the tank floated on the water, the welding heated it into fumes in the air pocket and then when it thought I wasn’t looking the ignition source of the weld pool did the rest.
I still weld many alloy tanks but refuse to weld steel tanks now. Life’s too short and I don’t need to speed up the aging process any more than what it already is.
I have heard that you can run a hose from the exhaust of your car into the tank. The fumes taking away any oxygen that a blast needs. It would confuse the Coroner though, wondering why you suicided in your workshop with your welder running.
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A while back I was working for a nut job mate who took on the repair of a large transportable diesel tank that had cracks in the bottom.
I said no but my boss said yes.
Asked the owner if the tank was empty and yes was the answer.
Laying on our backs in the hot sun chasing cracks good fun.
Bosses turn underneath when I heard a sound like the space shuttle warming up.
Yelled at the boss " f^^^n run " and took off.
He overtook me from a laying start.
The tank was not empty and diesel has a flash point just like everything else.
Lucky the tank had 2 vents but the fuel blew out and in the window of the bosses brand new Nissan Patrol which was parked near.
Never did get the smell out of that Nissan and we never finished the repairs on that tank ;D
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yeh as a young apprentice had a fuel tank out of a car to weld a crack. ran exhaust fumes out of a yz80 through it for a fair while. started oxy welding and wooompahh!! the rectangle tank was now a neat cylinder shape. used diesel fumes after that for years and no probs.
and i bet we also have stories about the split ring on truck tyres letting go when inflating!!
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O.K
More from me!
My old man old school mechanic, [and petrol head] told me, if you want to solder a petrol tank make sure the soldering iron is hot enough to solder BUT will not cause a piece of newspaper to light if held up onto it.
Plus good idea to defume it first. I welded several truck petrol tanks [the loader drivers ran into them a lot], my method of defuming as follows-
Empty all the petrol out DOH!
Take out the gauge tank unit and any removable fittings. The can hide a drop of petrol
Flush out with running water.
Get a piece of radiator hose and connect the exhaust pipe of a running truck to the filler neck, Ive used petrol engined exhaust.
Leave the thing running until the tank is to hot to hold your hand on.
This achieves evaporation of all the petrol left liquid in the seams of the tank and fills the tank with CO.
Now before welding I would stand aside from the filler neck etc, while the tank is hot and poke the flame of the oxy into the neck to ensure no surprise!
My method for soldering Motorcycle tanks, Remove all fittings ,flush out with water,Put your foot on top of the tank, lean back out of the way and stick the flame of oxy down the filler hole. It will flair. When its stops, instantly if you flushed it thoroughly, stick in again, and it mostly won't flair again. Leave it heating the tank till its hot to touch then weld .
Two points 1 I'm still around 2,But get someone else to do it.
cheers pancho
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I once welded the seam on a petrol jerry can using the "flair method" after washing it out several times with detergent and lots of water.
As those cans have seams that crimp together and form a substantial pocket I was a bit nervous about the deal so I left the gaarden hose flushing through it all night.
Next morning I lit up the oxy and it flaired as normal so I heated it up and welded it successfully.
After I finished it I decided I would never risk welding a jerry can again because of the seams.
The fact that it still flaired after running water through it all night proves to me that flushing alone is not good enough!
Cheers pancho.
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Well there you go Kenny, that's yet another reason why I don't like 2 strokes.
Come to think of it I'm not a fan of Diesel's either.
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Careful you don't receive the Dougie Mac award ! A bloke in our classic roadrace club had a leak in his Triton's alloy tank, drained it, ran the car exhaust through it and safely welded it up. Put it on the bike, hooked it up...and when he put a splash of fuel in to fire it up, discovered he still had a small but annoying leak. Incensed, he whipped out the gas torch, leaned in to the offending area and..kaboom !! :o
So much for the eyebrows... :D
No major damage done, but it could have ended much worse for him...
And he made the mistake of telling a couple of clubmates... ;D ;D
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I've done quite a few car tanks over the years, the funniest one is a 1934 Chev coupe we where restoring about 10 years ago, the tank was an oval shape and was full of dents so I figured I would do the heat it up with the oxy trick ala popping dents out of a chamber type of repair, I didnt have anything to block the filler hole etc up so smartie pants me had a brainwave.....went to Moorooka Yam and saw Boxy....yea mate, well have ago with the stuff we've got here.......I'd already done the flush thing for hours and waved the oxy in it so I thought sheee'd be right......we blocked up the ends, pumped her up with compressed air to I think 50psi and set to it with the oxy doing the circle thing on it.....all was going fine for about 10 minutes, the dents where coming out, it was a walk in the park......so we thought.......then boooom....bits of the blanking clamps flying through the workshop, blokes ducking for cover, ......faarrk.....what was that.....he looked at me, I looked at him .....we where both still intact..... and then we burst out laughing......we where rolling around the floor for ages.......lucky boys......the only downside was I now had a 10 gallon tank that held 15 gallons......off to the panel beater....argh Graeme old mate, I need to shrink this tank a tad....... ;D....it still cracks me up
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It’s not so much the fuel as the vapours that are dangerous.
It’s easy to be sucked in by getting away with that first weld but the heat from it will vaporize the fuel and then when you go to fill that last little pin hole….
Before attempting to weld a tank first check to see what fuel may be inside.
A torch may be beneficial for this check but it’s not something we often have handy.
If you can’t find a torch in your pocket then the trusty lighter will suffice.
http://www.youtube.com/watch?v=NtGOnbwxxiY
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Here's a funny one!
My first bike-500 AJAY I needed to check the oil level in the gearbox.
As this was a long way pre-unit [1952] the 'box has no connection to the engine. {except by chain}
So I unscrewed the filler cap to see the oil level, however I need light so my mate gave a match which I lit and held it over the filler hole and peered in the hole....WHOOMPER!!!!? Where the hell did that come from?
After I rubbed the remains of my singed eyebrows off my forehead I figured that the permanant feature of the petrol tap dripping on top of the gasket between the two gearbox housings had allowed some fuel to seep inside, enough to make an explosive mixture.
So I assume that those folk who restore these amazing machines with typical engineering of the old dart
where its acceptable to mount a tank on rubber and then use a short hard copper fuel line to the tap continue the tradition! Meanwhile I peer into all holes now days with suspicion! cheers pancho.
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Another one that springs to mind was from back in the 70’s.
My older brother’s mate was planning a trip around Aust. and wanted a long range fuel tank for his ute. For whatever reason my brother couldn’t be bothered making it ( probably because his mate was too tight to pay)
So his mate had some company make it for him. It was as wide as the tray and as high as the tray and around a foot deep along the length of the tray. I think he was planning to drive from Perth to Darwin with out fueling up.
So old mate rocks up to my brother with his new tank to get some bits of angle iron welded to the top and bottom corners so he could bolt it into the ute.
Apparently it was cheaper for my brother to do this than the company that made the tank.
They went through the process of fitting it into position and marking out where they wanted the brackets to hold it in place. It all looked really good with the rest of the tray still available for storage.
So they then took the tank into the workshop to weld the brackets on.
Funny how some sounds stick in your memory.
There was a mighty KaaaWooommmph and then a long whistling hissing sound.
The tank was well made. It didn’t split any seams, but it had gained instant pressure and the hissing sound was all that pressure whistling out of the filler tube.
These sounds were then followed by lots of swearing, some of which were new to me at the time.
Lots of accusations of “you must have put fuel in it already”, “you told me it was brand new”
They found out later that the company that made the tank swished some sort of chemical sealer around inside the tank to seal up any pinholes.
The sealer they used was flammable.
It took them quite a few hours of holding a piece of 2 X 4 on the tank and smashing it with a sledge hammer to try and get the rounded sides flat enough so it would actually fit back into the ute.
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Great stuff Geoff for some reason Banjo Pattersons "The Loaded Dog" springs to mind. Perhaps the sense of "build up" is what makes it funny! Cheers Jerry
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I was in a hurry to go riding one day and had to weld a coil bracket on my KX250, so I just wheeled the ute into the workshop with the bike on the back. I took the tank off and put it at the back of the tray and started welding the offending object.
All was going well until I noticed things were getting slippery underfoot............ because the tank had tipped over and fuel was runing out of the breather. I was oxy welding while standing in a pool of fuel! :o
How I got away with that one, I'll never know.................. ::)
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Yeah we had 4 painters killed down in the ship yard a couple of years ago, spray painting a hull section and one of then stood back to have a ciggy and admire the job...... whooommp .... don't know how many smoking related deaths I have seen in the shipyards over the years, saw 11 get wasted in Korea, but those Asian tank cleaning guys still love to smoke.
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1958. Nasho camp at Singleton.
All of us in our platoon were apprentice motor mechanics.
After a week or so the training officers were probably out of ideas so the got us all together with a bunch of 44 gallon engine oil drums and an oxy set.
The instuctions were to cut one end out of each drum with the oxy.
Who knows wot for [but that's the army]
Any how I was first cab off the rank so to speak so I cut the end off about 40 or so drums and one of the other blokes came up to me and said 'i've never done any oxy cutting show me how'.
So I obliged as I'd had enough and wanted to join all the other bored souls sleeping around the paddock.
I then took a seat on a near-by Jeep and dozed off against the steering wheel.
Note: The drivers seat on a Jeep is immediately on top of the fuel tank.
Meanwhile this other dude was on his third or fourth drum when KAAAWOOOMPH
I thought S#1+ I'm dead But actually I had run about thirty feet away from the Jeep before I woke from slumber.
What had actually happened was that the dude with the oxy came across an oil drum that had subseqently had petrol in it!
In true army fashion all the rest of the now wide awake soldier boys were paraded up to the far end of the compound and left to our own devices while the army ambulance carted the dude off.
The remarkable thing was no info concerning the incident was discussed with us regarding the injuries,where-abouts or anything about his condition was told to us.
About three years later I saw him, now a sales rep with quite an impressive scar on his right eye brow from the flying cutting torch and he said he recovered quite well from being blown about 30 feet onto his back and unconscious for some time. What did we do with the rest of the drums? we cut an end out of all the rest with a hammer and STEEL chisel!
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That is a bit of anticlimax... http://www.youtube.com/watch?v=jKezEwTwl0Y&feature=related
And this one welds the gas tank... with gas in it!! http://www.youtube.com/watch?v=hnz6s2g5HT8 Well, if it burns it wont explode right? The mixture is not right for the big bang.... Yet, quite scary!
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Picked up a Por15 kit today & will make up a couple of plugs to fit in place of the taps.
Couldn't find the leak at the front when I was flushing it, the seam along the top has been soldered at some stage & definately is 1 place giving problems
Will hopefully manage to seal it up this weekend but have been offered the use of a later aluminium tank for next weekend if I need it