Dent in the fuel tank

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skittles93, Jun 12, 9:11am
Hi guys I have a 72 roadrunner and I have a medium sized inward dent on the fuel tank. I have read in a few places to block off the lines empty all the gas and blow compressed air into the tank to pop it back out (it looks like it can be popped back out by hand). I am quite worried about blowing compressed air into a tank with gasoline residues haha. Would this be safe! Or better to take tank out and pop it out by hand!

plasticboys, Jun 12, 9:16am
not meanyroadrunners about my cousin had one over 25 years ago. good luckwith getting the dent out. l would do it the safer way

skittles93, Jun 12, 9:24am
Yeah too many mustangs and camaros in NZ thought I'd be a bit different ;) Cheers, yeah I don't mind doing it that way but if people have done this before and had good results then I will give it a go :)

skin1235, Jun 12, 9:32am
shet, on that I'd be doing it the long way, what chance have you got of getting another tank if something goes wrong and you balloon it, tearing out the baffles etc
if it is going to pop back out it will do so with less than 10lb of air in it so no danger of explosion ( petrol manages to stay stable at compression pressures of 180psi + in the engine) but as above why risk other damage

skittles93, Jun 12, 9:33am
Yeah true, I might just do it the long way. Do you think the tank would need to be replaced! Its not rusty or anything, but would a dent weaken that part enough to worry about!

skin1235, Jun 12, 9:35am
late thought, if you where really keen, mains pressure water is generally about 60psi, seal all outlets and wrap a towel around the garden hose etc, and use your hand arm pressure to hold it in the filler, stand well to one side when you release cos there will be a fair gush of water coming out
drain out the water chuck in a litre of meths and fill it up with petrol

skin1235, Jun 12, 9:37am
assume from your first post it is a simple push in type dent - you'll not get a creased dent out with air or water, close inspection of the rust protective coat will tell you if there is any damage, and another coat of goop will fix cracked protective coat - should have a new coat anyway just to be sure, at least in the dented area

toxicgreen., Jun 12, 10:02am
If creased more of a prob , but if shallow dent,there are various suction cups you cauld suck on to tank an pop dent out. Like glass companies ora panel beater or supercheep. Just an idea.

clark20, Jun 12, 8:24pm
Also check the pickup has not been bent up

budgel, Jun 12, 9:45pm
Also check the breather on your fuel cap. A blockage may be what caused the dent.

lookoutas, Jun 12, 9:48pm
Just chuck some air in it.
If that doesn't pop it out then you need to geta hand/lever inside. (Assuming the sender unit hole is big enough!)

If you put water in a tank, be careful chucking meths in as mentioned. This is only good on vehicles that are running every day - if petrol/water mixture is sucked through and left sitting in the carb, it will turn to white gunk, and you will not be happy! Need to run at least 3 tank fulls through in quick succession to avoid this happening. Even then, that might not be enough.
Too much of a risk IMO!

jsbike, Jun 12, 9:54pm
blow all the petrol fumes out of the tank with the exhaust fumes of another car

skittles93, Jun 13, 12:39am
Thanks guys :) I might invest in a heavy duty suction cup and try and pull the dent out, and the sender unit looks fine too!

lookoutas, Jun 13, 12:58am
It's not gunna blow-up if you poke a bit of air in it!

muzzaandmich, Jun 13, 1:01am
wait for it to BLOW,, its,another wind up or accident going out to happen

skin1235, Jun 13, 1:38am
not the sender unit thats the worry but if the pickup is now 3 inches off the bottom of the tank instead of the usual 1/2 inch, you're going to need a half a tank in it just to keep it running

dr.doolittle, Jun 13, 2:14am
You could try this.
remove the tank. Thoroughly rinse with water. Seal off all vents & make-up a temporary bung so you can fill with compressed air. Slowly & carefully heat the affected area with a blow torch or hot air gun. the dent should swell out.
Works well on 2 stroke MX bike expansion chambers.
Just be careful not to be leaning over any vents in case your bungs decide to let go.

lookoutas, Jun 13, 2:45am
Do this and you'll surely finish up with a pregnant tank and a head somewhere else.

lookoutas, Jun 13, 6:50am
Sorry dr doo - a hot air gun would be my limit. Naked flame! No way!

skittles93, Jun 13, 6:51am
ye true, I might just take the tank off and check if everything is fine in that case!

vjregal770, Jun 13, 11:47am
Mine's had a dent in the tank since I've had it. Never been an issue. It must mean it costs a little less to fill hehe

Not that it really matters at 27 gallons.

jono2912, Jun 13, 2:26pm
You'd be fine with no fumes, and he dealt with the fumes by cleaning the tank. Just sure you get it real clean, heavy duty degreaser will do.

mrfxit, Jun 13, 9:17pm
Ha ha h a h a h a ha ha ha LMFAO. BANG

mrfxit, Jun 13, 9:19pm
There are VERY SPECIFIC chemicals & cleaning methods for making fuel tanks SAFE.

lookoutas, Jun 14, 5:41am
That's right - and that means "Rinsing with water ain't good enough"
And just remember - If you do defume a tank, work on it straight away/continuously. If you go away and come back, it will have regased itself.