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Removing Tank Sealers

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Post Mon Sep 22, 2008 6:42 am
Pa Site Admin

Posts: 5841
Location: Ohio USA

My Buddy used MEK to remove Kreem from his fuel tank. MEK worked pretty well but it still left a little in the tank here and there. Thinking he could get it out with another chemical, he tried using laquer thinner on the remnants. The laquer thinner didn't do a thing so he went back to the MEK. The MEK won't do anything now. My question is, did the laquer thinner change the chemical makeup of the tank sealer so that the MEK can't touch it now ? What should he do to get the rest of the sealer out, now that he blundered by switching chems ? Thanks, Pa

Post Mon Sep 22, 2008 6:55 am

Posts: 426
Location: Tucson Arizona

Paint stripper.........unless the tanks are painted, then I don't know what to tell you.

Post Sat Sep 27, 2008 11:08 pm

Posts: 144
Location: Union, SC USA
Try some Acetone. I have to use it occasionally on screen frames at the shop, that have old crusty ink build up on them. Just a thought. I have since found a similar problem on another board. They had the same problem using Kreem and MEK. He left Acetone in the tank for about a week, and that got rid of all of the undissolved Kreem. Then check out POR-15. A lot of guys are swearing that it is the best tank sealer out there. We used it on a four wheeler tank with about twenty pinholes, and it has stopped them all. JMO. Good Luck Bro.

Post Tue Oct 14, 2008 11:30 pm

Posts: 1538
I agree with Psycobilly, + I have had good results removing Kreem with Acetone as well.. Long soak though...

Por15 is the way to go, IMO.......

Post Wed Oct 15, 2008 5:43 am
Pa Site Admin

Posts: 5841
Location: Ohio USA

Thanks Bro's ! I'll have him go that direction. Pa

Post Wed Oct 15, 2008 7:04 am

Posts: 3159
Location: Central Illinois, USA
I found the safest direction to be away from sealers.


Post Mon Oct 20, 2008 11:32 pm

Posts: 1538

But then ya have the issues of tank rust... No ??

Post Mon Oct 20, 2008 11:52 pm

Posts: 2688
Location: Los Angeles, CA
sleeper wrote:

But then ya have the issues of tank rust... No ??

Oil will stop any rusting. Gasoline is oil and as long as the tanks have gas sloshing around in them they wont rust.

Post Tue Oct 21, 2008 7:16 am

Posts: 3159
Location: Central Illinois, USA
We all know:
Water can separate from gasoline, and sit at the bottom to do damage if left un-attended for extended periods.

Tops of tanks don't rust through, the bottoms do.

Machines in service are shook up and purged often enough to prevent the problem.
It's garage queens that are at risk.

Since USA fuels no longer have a decent 'shelf-life', topping them off for storage might not be such a great idea any more. (Not to mention the fire hazard....)
I drain and swab them out dry.

Swab them with mineral oil if you are really worried.

(My flexible non-sparking swab is a length of soft copper water tubing flattened at one end. I split an eye in the end with a chisel, and loop a rag through it:


Post Tue Oct 21, 2008 11:36 pm

Posts: 1538

Agreed, the water (being heavier than P4Gas) does sit on the bottom..There-in lies that problem..

However, sealers have improved, ie: Por15

HD (modern) moco has been coating tanks (different coating) for about 2 decades that I know of..
Even in the Service Manuals it states if tank is dirty, wash it out with warm soapy water & let dry...No rust or worries..

Now that works for me..

Post Wed Oct 22, 2008 6:23 am

Posts: 3159
Location: Central Illinois, USA

My experience with sealers is that they were better in the past.
My wife's rat has had Kreem in it since the mid 80's, stained but otherwise in perfect condition to this day in P4gas. Modern Kreem doesn't seem to have a good reputation, however!

POR-15 lasted 15 minutes for me before it softened, then expanded and wrinkled into shreds in summer-blend Shell Premium.Cost me $$$$$$!

Caswell's epoxy lasted a few months.

I have witnessed a red rubbery coating suddenly melt out after many years of good service.
(Thin red varnish-like sealers from radiator shops may deteriorate over many years, but at least they don't glob up things!)

It would be nice to know what the Factory uses, but it still may only be a matter of time before digestive additives, or illegal dumping, take their toll.

It is a gamble to depend upon any sealer to stay put; Rust is the lesser risk!


Post Tue Nov 04, 2008 7:43 pm

Posts: 5
I have a repro set of J model HD tanks. Right side is half oil and half gas, left side gas. Put a double coat of Kreem in all of them. They are just primed, so now is the time to strip that stuff back out. Im thinking of leaving it in the oil tank and just stripping out the gas tanks.
or should I just get rid of it all? Kurt said to try paint stripper, anyone ever tried this? Got a paticular brand name?
All input appreciated....Rod

Post Wed Nov 05, 2008 12:01 am

Posts: 1538
Acetone will slowly dissolve Kreem..

Post Wed Nov 26, 2008 12:47 am

Posts: 1538

From what I've recently learned, HD may now agree with you..
As I understand it, starting for the 2006 & newer fangled harleys, the gas tanks are NO longer coated...

says even their oem coatings can possibly slowly dissolve away.. (or the bean-counters are doing away with the cost) ??

I don't know ? my daily rider is 15 yr old FL & still has the oem coatings & looks coated well in my tanks.....
Last edited by sleeper on Wed Dec 10, 2008 12:22 am, edited 2 times in total.

Post Wed Nov 26, 2008 12:47 am

Posts: 1538
:oops: hit da button twice (apparently)...

Post Wed Nov 26, 2008 5:33 am

Posts: 3159
Location: Central Illinois, USA
Staying one step ahead of the ever-increasing digestive additives in modern fuels is a real challenge.

Even the float material that I cut has been reformulated since 2006.


Post Thu Nov 27, 2008 1:41 am

Posts: 1538
"Staying one step ahead of the ever-increasing digestive additives in modern fuels is a real challenge".

Yep, seems that today's P4gas (your term) is pretty brutal.......& seems to go stale much sooner as well IMO..

Post Mon Dec 15, 2008 9:05 am

Posts: 3159
Location: Central Illinois, USA
I recently dragged a set of 3.5 '63-'65 tanks out of storage that I obtained in '75, and observed a drooling tar-like sealer applied to the seams inside.

After nearly a month of acetone soak, many days of of it tumbling with aquarium gravel and acetone, I find that although the sealer softened, it still adheres and does not dissolve.

Attached is a photo of some of the material after it is scraped loose.
(As always, external photohosting sucks; clicking on the thumbnail will enlarge it, but take you to imageshack)

Before the acetone soak, it resembled the adhesive used to secure the felts in Panhead valve covers. Anyone know what the felt adhesive compound might have been?


Post Sat Dec 20, 2008 1:34 am

Posts: 1538
Sorry Cotten, no answer here.. these days 3M makes the felt glue, I've used..

As to your treasure you found...looks like some gizzard guts from a post-mortem operation..

How bout putting it on ebay ?? gotta use the magic words "Old School" & of course obsolete...And any additional vernacular you deem fitting... :lol:

I still have a vivid mental image of you holding the 'pink goo' outta the last tank you posted the pic to...(yuk!)

Post Sat Dec 20, 2008 7:34 am

Posts: 3159
Location: Central Illinois, USA
I am continuing to tumble the tanks with acetone, and although the material expands dramatically and becomes gelatinous and transparent red/brown, it never dissolves or tints the solvent!

Upon drying, it shrinks to become the tough rubbery material shown.

Although temperatures are low in my shop, it is still ironic that a piece of it bottled in summer blend Shell Premium doesn't appear affected at all.



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