testing oil tank

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maylar

maylar

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A buddy of mine is trying to find the source of an oil leak on his 72 Interstate. He's wanting to pressurize the oil tank somehow (off the bike) to look for cracks. Has anybody done this? Any tips?

Thanks
 
I used a very unsafe method to test a gas tank. Stuck an air hose with valve into the tank, bled in some air while holding back pressure with a rag over the filler neck and looked for leaks with soapy water. Don't use this method, I'm surprised I didn't kill myself.
 
I would also advise against using air. My opinion would be to clean and dry it very well then block off the fittings and fill with mineral spirits or other very thin solvent. This will weep out if any problem areas easily. And is much safer than pressurizing something that is designed for no pressure.
 
Air pressure or sucktion could deform the tank, use alcohol or gasoline as its plenty thin at room temp ,or put filled tank in boiling water then remove and look and smell of leaks to solve. If at base mount boss, I'd be sorely tempted to clean and pout in a layer of JBW to beef up permanently.
 
I think you're all being a bit over-cautious regarding pressurising the tank, it would only need a couple of psi or so to show up a leak, I think the tank would cope with that ok. I'd use a max of about 5 psi,

Dave.
 
I was witness to an act of stupidity when I worked for Cessna. They resident yokel decided to leak check a rectangular aluminum brake resivor. As his crew chief noticed what he was doing, half way thru telling him to stop, the tank blew a seam. Luckily no one was hurt. I don't advise pressurizing anything not designed for pressure, even taking precautions, shit happens. There are plenty of safe ways to find a crack. As I stated before, clean and dry completely, plug outlets and fill with mineral spirits. You could dust the outside with flour to help identify the crack.
 
Duh, hicks just put it under water after plugging the vents and/or also blowing into a hose while under water, if need be.
 
I took mine up to the local rad shop, they sealed it up, pressurized it and put it in their dunk tank. No leaks. Cost me a coffee.
 
I have an old diaphragm air compressor for an air brush and I use that to supply the air while I hold it under water. It only puts out 2-3 PSI, certainly wouldn't want to use much more than that on an oil or gas tank, these are not a pressure vessels.

Dave
 
Both my oil tanks showed pin holes in the bottom around the support mount/bolt. If your tank is off the bike, I would weld/braze the bottom regardless. I think this a standard practice of CNW in their restoration.

Good luck.

Tom
 
I just tested mine, a brazed repair on the rear mounting tab made me suspicious. At the hardware store I got 2 expandable test plugs, 1-1/4, 1-1/2, for fill and big banjo fitting. Hose niples blocked off with hose. 3 PSI and soap bubbles, did a Triumph fuel tank the next day. Been doing this for years. Works fine, no drama.
 
I sealed mine up then used a foot pump. Soapy water soon showed it was a leak from around the bottom mount.
 
You could just submerse the tank upside down and treat it like a diving bell. Plug the oil return line, put in the drain plug and turn the feed banjo to point toward the top. Just push it under water and look for bubbles escaping from places they shouldn't. It will only test about the bottom 2/3 of the tank but that is the area that has the oil sitting in it. No pressure required.

Russ
 
Another method that worked for me was to seal off all the openings. OK to use the cap. Then submerge in soapy hot bathtub. The air will expand slightly because of the heating (PV=nRT) and provide some pressure to see the bubbles. Short answer... take a bath with it.
 
Anyone got a quick way to plug the banjo hole without actually having the screenbolt?
I've looked around the shop but Ive nothing that size or thread for the dunk test
*Nevermind found a rubber bung off something or another that'll do the trick
 
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