Topic: 1977 CB550F Gas Tank Sealant Failure

[MLW9110]

I thought I had my CB550F pretty well figured out but yesterday it started losing power on acceleration and I couldn't maintain speed on hills. I checked the gas tank first and found that tank sealer done by a previous owner had failed. There were big chunks of loose sealant as well as large pieces of coating that flaked off. I got what I could out but there is still a lot left on the inside of the tank.

I took a piece of removed sealant and put it in acetone. I took another piece in CitriStrip. After soaking overnight, neither piece was affected.

I put the tank in an box and put it in the dryer. I packed another box and a bunch of towels and blankets around the tank. After an hour in the drier, there's a lot of sealant adhering still. I'm going to try some other kind of stripper, Aircraft Stripper is one choice.

I'm not sure what the sealer is. It's gray in color. I think it might be POR 15.

I checked with a local radiator shop and was told that the chemicals they used to have that worked were taken away from them.

The tank isn't pretty and has dents but I don't mind it that way, I just want it to hold gas without clogging things up!

Anyone have any suggestions?

An alternative would be to buy an aftermarket tank. I'm not sure what is available that would fit without modification though.

[BenelliSEI]

Checkout the “paint stripper” thread right below your post:

http://forums.sohc4.net/index.php/topic,195910.0/topicseen.html


I’d start looking for another tank……

[MLW9110]

Checkout the “paint stripper” thread right below your post:

http://forums.sohc4.net/index.php/topic,195910.0/topicseen.html
9mm

I’d start looking for another tank……

The paint stripper thread refers mostly to paint stripping, not tank sealer. I'm going to put some of the removed stuff in brake fluid overnight.

I am looking for another tank. If I could find an aftermarket tank that would fit I'd try it.

[MLW9110]

Checkout the “paint stripper” thread right below your post:

http://forums.sohc4.net/index.php/topic,195910.0/topicseen.html
9mm

I’d start looking for another tank……

The paint stripper thread refers mostly to paint stripping, not tank sealer. I'm going to put some of the removed stuff in brake fluid overnight.

I am looking for another tank. If I could find an aftermarket tank that would fit I'd try it.

I used MEK a lot when I worked on airplanes. It worked great for degreasing parts and removing PRC sealant from my hands. It's on my list of things to try.

We used to call it Methyl Ethyl Death when we had MSDS training.

[CycleRanger]

Is there rust under the liner? That's what usually causes them to fail.
If there's rust you might try some vinegar to dissolve the rust and lift the rest of the liner.
If it were POR-15 acetone should affect it.

[MLW9110]

Is there rust under the liner? That's what usually causes them to fail.
If there's rust you might try some vinegar to dissolve the rust and lift the rest of the liner.
If it were POR-15 acetone should affect it.

Thete is rust under the liner. It's not POR15 if acetone should affect it. I have a piece of liner in brake fluid. I'll check in the morning if it's working.

[newday777]

Is there rust under the liner? That's what usually causes them to fail.
If there's rust you might try some vinegar to dissolve the rust and lift the rest of the liner.
If it were POR-15 acetone should affect it.

Thete is rust under the liner. It's not POR15 if acetone should affect it. I have a piece of liner in brake fluid. I'll check in the morning if it's working.

Electrolysis cleaning method may break the liner loose as it removes the rust under the liner. Rust left in tanks is the usual cause of liner failure.
Is the liner a hard epoxy, or a soft liner that is flexible?

[Stev-o]

Is there rust under the liner?
If there's rust you might try some vinegar EvapoRust to dissolve the rust...

FTFY

[MLW9110]

Is the liner a hard epoxy, or a soft liner that is flexible?
[/quote]

It's soft and flexible. The big lumps break up into smaller chunks. I had a hard time getting the lumps out because they would break up as I tried to get yhem through the filler hole.

[bek1966]

I tried using MEK on a failed POR15 liner and it wasn't effective.  I ended up sending the tank to Fuel Tank Services in Ft. Lauderdale, Florida to have the old liner removed and a new liner applied.  They do very good work, but are not cheap.

[RAFster122s]

vinegar eats metal indiscriminately, I won't use it on a tank, metal is too thin and you just might cause a lot of pinhole leaks. The rolled steel has a surface treatment or a result of manufacturing and after the vinegar eats through that the tank rusts faster or more completely than it did before.
Acetone will destroy your paint but will dissolve most liners, in case of por15 if a huge chunk of it sets up in the top of the tank because the PO didn't follow directions or didn't drain out what didn't coat as described in the instructions then you end up with a thick chunk that is going to be difficult to dissolve. I have a CX500 tank with screwed up liner if POR15 and the kid that did it let a massive pool setup in the top but it didn't adhere properly because he didn't clean the tank correctly and neutralize the rust. So, when I stripped the liner I was rewarded by a huge chunk of liner separating from the top but too thick to dissolve.  It bounces around in the tank rear inaccessible. I haven't figured out how to remove it unless I cut the tank open.
The stopper I had in the tank full of acetone popped out and I lost 100$ of acetone as a result. Probably $150 now or more for 5 gallons today.

[MLW9110]

I put a quart of acetone in and am going to leave it for a few days and see if it does anything. I'm sloshing it around with the drywall screws in and letting it sit in different positions.

[seanbarney41]

vinegar eats metal indiscriminately, I won't use it on a tank, metal is too thin and you just might cause a lot of pinhole leaks. The rolled steel has a surface treatment or a result of manufacturing and after the vinegar eats through that the tank rusts faster or more completely than it did before.

This is not true if done properly.  Yes vinegar is mildly acidic and it does eat metal, but only very slowly.  I have de-rusted somewhat pitted tanks with off the grocery shelf vinegar for up to 14 days.  Most of the real action takes place when  you neutralize the acid with a baking soda solution, and then you gotta dry the inside of the tank asap and get it coated with oil.  I have tanks that have had this process done that have served great for 10+ years and tens of thousands of miles now.

[MLW9110]

"If it works good, it looks good..."

That's how I feel about my CB550F.

I have used vinegar with good results. I've used fogging oil in a gas tank after the vinegar treatment too.

[seanbarney41]

I usually use 2 stroke oil to coat the inside of a freshly dried, de-rusted tank...no real reason other than I usually have some around

[MLW9110]

I left acetone in my tank for a couple weeks. Didn't do much. It definitely did not dissolve the coating. Today I drained it and took the sheet rock screws out.

I put a quart of kleen strip paint stripper in with a length of chain. The stripper has methelene chloride in it. I'll let it work for a while.

[MLW9110]

It's working!

[CycleRanger]

I've not used that Klean strip on tank liner but I have used it for paint removal and it works very well.
Glad you're seeing some progress.

[MLW9110]

Well, the stripper got some of the remaining liner out but there’s still some material that won’t come out. I’ve had cleaning vinegar in the tank for about a week now, it’s not getting it all either. Also have sheetrock screws in.

[MLW9110]

Vinegar got a lot of the remaining liner after about 3 weeks of soaking and agitating with sheet metal screws inside. I drained the vinegar and put in muriatic acid and after a couple days of agitation and scraping off what I could get at I got the most stubborn remaining liner out. I drained the acid and rinsed with water. I put some evaporust in overnight and rinsed again. I was pleased with the way the tank interior came out.

BUT!
Rode the bike today, it’s still not running right. I’m going to have to troubleshoot that later. Meanwhile, there is a small seep at the lower left rear of the tank. Might be why the tank was lined. @#$&*!

I think I will see if I can get the seep welded before I resort to relining. Probably will use Red-Kote if I have to.

[CycleRanger]

Vinegar got a lot of the remaining liner after about 3 weeks of soaking and agitating with sheet metal screws inside. I drained the vinegar and put in muriatic acid and after a couple days of agitation and scraping off what I could get at I got the most stubborn remaining liner out. I drained the acid and rinsed with water. I put some evaporust in overnight and rinsed again. I was pleased with the way the tank interior came out.

BUT!
Rode the bike today, it’s still not running right. I’m going to have to troubleshoot that later. Meanwhile, there is a small seep at the lower left rear of the tank. Might be why the tank was lined. @#$&*!

I think I will see if I can get the seep welded before I resort to relining. Probably will use Red-Kote if I have to.

I would recommend POR-15 personally.

[RAFster122s]

Caswells epoxy liner is a little easier than POR15 and either are good choices
 Redkote would need to be reformulated from its older version which wasn't long term stable with the use of ethanol based fuels. While pure gas is ideal, sometimes you won't have access to ethanol free fuel.
The passages in carbs are very tiny and won't take much debris or buildup of deposits to cause carb problems.
Once you have your brass out of the carb then an industrial ultrasonic cleaner can break up any deposits or clogs in the carbs to get them clean again.

[rotortiller]

MLW9110, this is what my POR looks like after 8 years. Not sure if it matches up to what you have peeling away. Regardless the situation sucks.

[MLW9110]

I soldered the pinhole and haven't had any more leaks so far.
Thanks everyone for the input!
Mike