The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: rustedframe on March 10, 2021, 08:18:36 PM
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So, I've rehabbing/restoring an '83 R65. It's been a joy. I'm almost done. But the tank has been sitting on the shelf.
So, after I got both wheels back on, I decided I need to work on the tank. I thought, "oh, no problem - a little rust, I'll use metal rescue and it will all be good". I've used metal rescue in the past and had great results. It's cleaned up a few rusty tanks.
But. I discovered the PO had used some sort of tank liner. And, it looked like the liner was either mis applied or had failed somewhat. There were LARGE chunks of plastic like material loose inside the tank. insert swear words. Loose as in your could hear them rattling around if you shook the tank. Like there were rocks inside.
So what to do. I rattled the tank around and grabbed a few with needle nose pliers. That gave me an idea of the size. Then I spend 2 days with a "flexible grabber" (the thing you use to grab nuts that have fallen on your truck's cross member). That worked pretty well. I could grab the 2-3" pieces and then break them in pieces with the needle nose. But that's super tedious. I barely have that much patience.
I finally got the pieces down to the size that a small plastic hose connected to the shop vac could suck them out. And then a wash or two with water flushed out the remaining bits.
But wow. what a pain. I will *never* use a tank sealant. Never.
I've had amazing results with electrolysis, and vinegar. Vinegar being my favorite. Between those two no corrosion can stand. Vinegar is amazing given 24-48 hours. And Electrolysis will remove the cruftiest rust. I'm a huge huge fan of POR-15, but I'll never put goo in a gas tank. Never. I'd rather grind out the pinch welds and re-weld it back together.
Ok. This is a rant. Sorry. I just needed to vent.
The good news is tomorrow it will be almost 70F. And I plan to ride one of my bikes. And install the front brake line on the R65, which means I *could* start it (since, with the brake line in, I could connect the throttle cable). The Bings are calling me. Carpe diem. Time to tune the idle circuit - since we' don't idle on the mains.
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I've de-rusted three fuel tanks, I used 9% acid vinegar in two tanks, took about a week .
One had Kreem liner, needed muriatic acid and MEK to remove the failed liner .
Only issue I had, was flash rusting in rinsing out the vinegar with water .
I used a small amount of phosphoric acid and it removed the rust, washed out the tank with denatured alcohol used warm air exhaust from a shop vac to evaporate the alcohol .
I used POR-15 fuel tank sealer on all three tanks, so far 12 years later the liner is still holding up in all three tanks .
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Sounds like no fun at all! I just had the standard red liner failing. Multiple swooshes with hot soapy water until no more bits came out. Then a dry in the glorious UK sun.
I've not used reserve since, but have got a moderate sized inline filter just after the tap just in case.
I'm touching up the paint soon, so have let the tank run lower than usual, so will have a poke about when it's off and see what lies beneath :beehive:
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I did mine with vinegar and salt. Took about 4 days to get it to bare metal
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I had great luck with Ospho. It's phosphoric acid, but it's got some special herbs and spices that leave a better protective coating and produce less flash rust than plain old phosphoric.