Does anyone have experience with the KBS Coatings or the Eastwood tank sealer kits? After a few years of faithful service my NWMP aux tank finally started to leak (the production date on it is 1991, and it spent most of its life in the salt belt before I got it). Right now it's mainly a strong smell and a little bit of tell-tale residue on the side and on my spare tire. It's leaking from the driver side mounting bracket, I would assume because the galvanizing on the inside was burned off when the bracket was welded on during manufacture. It's probably not widespread rusting on the inside, I would imagine just localized to where it was welded together so it should be repairable

I think the KBS kit has some advantage since I won't have to use muratic acid and acetone during treatment + they say the coating is a flexible urethane whereas it sounds like the Eastwood product is more of an epoxy. I would think a flexible is better since the tank is hard mounted to the rear cross member and probably sees a bit of flex now and then.

Oh yeah, since no one likes threads without pics, here's the leak


and it's mounted on this rig

 

For anyone looking in the future:

I sent NWMP an email explaining what was going on though (and to ask if I could get a discount on a new one even though this one is 20 yrs old). They suggested I try a radiator repair shop and said I could buy a tank without the install kit for ~$100 less than the regular retail price. Their tank guy didn't have any experience with the liner kits I linked above, so he didn't have any advice on which might be better.

I already tried a JB Weld type gas tank putty which helped but didn't stop it from seeping gas completely - I never really had a drip, just a strong odor and a wet spot trickling down to my spare tire.

I ended up going with the Bill Hirsch tank sealer kit: www.hirschauto.com/prodinfo.asp. I didn't read one bad review in any of my research about these products and it's supposedly the same type of sealer used in aircraft tanks, it that means anything. I went with this product partially because you can save any leftover product to put in a second coat if you want. Also, I saw plenty of restoration companies using this one. A side benefit is that it happened to be the cheapest at only $46 - now I just have to drop the tank and get it done.

I've read about instances where the POR and KBS Coatings separate from the metal, in effect creating a floating bladder within the tank. This may have been user error in the prep stage, but it seemed like a common possibility among most urethane based coatings with bits breaking off here and there and later clogging fuel filters. I read a whole bunch about a product called Kreem, most feedback was neutral but there was also a lot of negative. The main problem with Kreem seems to be that if you mess up the prep stage and it starts to come away from the metal you're only recourse to remove it is to burn it out. KBS and POR can be removed with muriatic acid.

All the products basically follow a 3 step process with thorough dry times in between:
1) some form of cleaner, often muriatic acid, to get the varnish out
2) some nasty chemical to rid the tank of rust and etch the metal in preparation for the sealer
3) the sealer itself, followed by a few days of dry time before re-installation

. . . when I get it done I'll update the thread with my thoughts & impressions on the product and process

 

I started the process by pulling the tank out of the 4runner. I'm REALLY surprised how clean it is on the inside, I was expecting a lot more varnish in this 20 year old tank. You can see the rust spot which is the source of my pinhole leak - I had thought I'd find rust where the welds are (burned off zinc coating) but that's not the case. You can also see the little bit of varnish that is inside the tank just below the welds and extending to the right.



I plugged or capped all the vents and openings before mixing the "Miracle Heavy Duty Marine/Industrial Cleaner & Degreaser" in a 1:1 ratio with some hot water. The instructions say to use the full quart bottle, but since it wasn't heavily varnished I only used 1/2 of the bottle. I let it sit for a day and occasionally shook it up a bit or rolled the tank around to get all the sides wet and let it do it's thing. The next step is to let it dry completely and then use the "Tank Etch" to prepare the surfaces and remove the rust so the sealer can have maximum adhesion.

This is what the Tank Etch looked like when I poured it out. It was as clear as water when I poured it in, now it's a rusty/grey color



This is not what I expected to see after the tank etch. It knocked down the mound of rust by the bracket on the far side, but it looks like it spread it everywhere else inside the tank now.



Here's another pic after the tank etch was allowed to dry for a few days, I also stuck my wife's hair drier into the filler neck for 20 min before the next step.


I shook up the sealer and poured it in, rolled it around for a few minutes and then hung it up to drain - the instructions are very explicit about not letting the sealer pool up, so drain it once all the insides are coated. BTW, there was some serious off-gassing when I poured it in (just like the tank etch) that's why the tape over the vent valve at the top allowed some sealer out


The sealer contains a healthy dose of methyl ethyl ketone and is very potent, so when they say "well ventilated" area they mean it. I could literally see the vapors pouring out of the tank filler and vents. As it's drying this stuff reminds me of rubber contact cement, but when completely cured its "dry" to the touch and still flexible - sort of reminds me of a white liquid latex. I wasn't able to peel away the bit that I got on my nitrile gloves, so it has good adhesive properties which gives me some confidence that it'll stay put in the tank.

Here's what the tank looked like after the first coat of sealer (not sure why the pic is so blue, the coating is actually milky white)


Here's the finished product after the second coat (still wet in this pic). The little chunks all over the inside are bits of zinc oxide from the Tank Etch - I probably didn't need to use the Tank Etch a second time and would advise against it in the future, though these chunks aren't going anywhere.


I let it cure for 1 day after the first coat and 2 days after the second coat before re-installing it. Now I'm just going to wait a few more days before putting gas in it again.

 

just curious when you went to all the trouble.

Was it to prevent more problems in the future that you didn`t have the tank welded. Was it fix one leak another in a few months. if it had been welded.

 

Hello Corax.. I just seen your thread. I used Red Kote and havent had any problems. I havent tried the brand you are using and am sure it is just as good. I have about 6000 miles on mine and no problems. But you are right, it is all about the prep time.

 

I think the leak/rust hole was caused by water getting between one of the mounting brackets and the tank itself before I re-coated it a few years ago. In order to weld it I would have had to strip off the spray on truck bed coating and a nice layer of POR to get to metal. Then there would still be rust to help blow a hole through the metal when welding.

 

I hope this works for you I don`t see why it wouldn`t.

Like you said it is all in the prep work