Deteriorating Gas Tank Lining

C

corey

New member
Jan 7, 2010
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Good evening GMC'ers, we've got the tanks out of our newly acquired coach and I'm trying to decide the best course of action. The gas tanks have
apparently been 'DIY' coated on the inside in the past. Both tanks have a cream-colored coating on the inside of the tank. The main (rear) tank was
NOT coated that thoroughly and has many exposed metal areas that look clean and rust-free. The areas that do have sealant on them have minor bubbles
in the coating, but so far none has broken free. I THINK this tank looks good at lest for another few years. The auxiliary (front) tank, however, Was
thoroughly coated, but it is beginning to peel. There are large sections that you can see have broken away and there is exposed rust underneath. We
are taking just the auxiliary tank to a shop that will tumble it tomorrow and hopefully remove all of the rust and old sealant. The shop tells us that
if the tumbling process does not remove all of the old sealant, they will not be able to apply their own sealant to the inside of the tank. My
questions for the group are: 1) Am I OK to continue with the main tank as it is? The sealant has just minor bubbles in it in the areas where it is
present. In the areas where it is not present, the metal looks clean. 2) If the shop tumbles the aux tank and is not able to remove all of the old
sealant - what are my options? Use the tank as-is with a lot of exposed metal? Ask them to try to seal it anyways? Try to seal it myself?

Thanks in advance,
Corey
--
Corey
1974 Unidentified GMC Trim
 
I am fighting a similar issue and resisting coating the insides of the tanks after received several reports from reliable GMC sources of peeling
sealant. I have not been able to find out what brands of sealant was used. One of the sealant companies has stated that when sealing, the excess
MUST be drained out completely before drying. Otherwise the sealant will not cure completely causing later bubbling.

If I was refurbishing a tank, I would take it to as stripper and have them chemically clean it. These places have a huge tank of chemicals unknown to
me where they can submerge an entire car if necessary and remove all foreign stuff including rust.

Tumbling is not going to work because there are internal baffles that will prevent the media from getting to all areas of the tank unless you cut them
open and later weld back access ports to the baffled areas. I have a friend that had an entire car frame done by one of these companies in
Indianapolis named Pro-strip. I do not know where you are located but there is a chain of these shops around here named Redi-Strip plus other
independent ones. I would take the tank(s) to one of these places and get their advice.

Tumbling is not going to do the whole tank and might damage it depending on what media they use.

Once you get it stripped I would solder up any leaks and paint the outside with POR-15 or similar product and top coat that with white Rustoleum on
the bottom at least. It is your choice if you want to re-coat the inside or not.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
The shop says that to get to the chambers outside the baffles, they would drill holes in the tank to get the media in, then patch them back up when
finished. Tumbling 'media' is metal bits... small nuts, bolts etc.
--
Corey
1974 Unidentified GMC Trim
 
Rust is an oxidation reaction, not unlike burning. The reddish powder that
comes off on your hands when you wipe your hand or a cloth over it, is the
ashes of that metal that was consumed in the reaction (fire) the tank
thickness is reduced by this process. That metal is lost back into the
environment that it came from. Ashes to ashes, dust to dust. Fact of life.
Can't change it. When holes rust through the tank, you need a new tank.
Just how it is.
Jim Hupy
Salem, Oregon

On Tue, Dec 17, 2019, 11:11 PM Ken Burton via Gmclist <

> I am fighting a similar issue and resisting coating the insides of the
> tanks after received several reports from reliable GMC sources of peeling
> sealant. I have not been able to find out what brands of sealant was
> used. One of the sealant companies has stated that when sealing, the excess
> MUST be drained out completely before drying. Otherwise the sealant will
> not cure completely causing later bubbling.
>
> If I was refurbishing a tank, I would take it to as stripper and have them
> chemically clean it. These places have a huge tank of chemicals unknown to
> me where they can submerge an entire car if necessary and remove all
> foreign stuff including rust.
>
> Tumbling is not going to work because there are internal baffles that will
> prevent the media from getting to all areas of the tank unless you cut them
> open and later weld back access ports to the baffled areas. I have a
> friend that had an entire car frame done by one of these companies in
> Indianapolis named Pro-strip. I do not know where you are located but
> there is a chain of these shops around here named Redi-Strip plus other
> independent ones. I would take the tank(s) to one of these places and get
> their advice.
>
> Tumbling is not going to do the whole tank and might damage it depending
> on what media they use.
>
> Once you get it stripped I would solder up any leaks and paint the outside
> with POR-15 or similar product and top coat that with white Rustoleum on
> the bottom at least. It is your choice if you want to re-coat the inside
> or not.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I would still prefer chemical to mechanical removal.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Applied has new tanks. Not cheap but I sure wouldn't throw good money at pinhole tanks and have to do the job again or leak fuel and lose the coach.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Best thing to do is take the tanks down to your local radiator/fuel tank shop and have them look at them....they will recommend the best solution. All
the classic cars i have restored they have "hot tanked" them to clean them inside and out then sealed the outside with a corrosion barrier paint. As
for the inside, unless they are heavily rusted they will leave them bare steel and as long as there is fuel in them they will stay in good shape.

As far as coatings i have tried the usual's that are commercially available and find they tend to cause more problems then they are worth inside a
fuel tank because unless the prep is done exctly as they say it doesnt stick [example: POR15 is a fantastic product and sticks like no tomorrow to
rusted or sand blasted surfaces but will peel off in layers on smooth steel].

YMMV but contaminated fuel systems are too much of a pain to deal with on the side of the road so let the experts deal with your tanks for the few
dollars it really costs.
--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
I do have a set of pristine Cinnabar tanks that I don't need. They're
expensive though and shipping would be as well.

bdub

-----Original Message-----
From: Gmclist On Behalf Of Corey via Gmclist
Sent: Wednesday, December 18, 2019 12:20 AM
Subject: [GMCnet] Deteriorating Gas Tank Lining

Good evening GMC'ers, we've got the tanks out of our newly acquired coach
and I'm trying to decide the best course of action. The gas tanks have
apparently been 'DIY' coated on the inside in the past. Both tanks have a
cream-colored coating on the inside of the tank. The main (rear) tank was
NOT coated that thoroughly and has many exposed metal areas that look clean
and rust-free. The areas that do have sealant on them have minor bubbles
in the coating, but so far none has broken free. I THINK this tank looks
good at lest for another few years. The auxiliary (front) tank, however, Was
thoroughly coated, but it is beginning to peel. There are large sections
that you can see have broken away and there is exposed rust underneath. We
are taking just the auxiliary tank to a shop that will tumble it tomorrow
and hopefully remove all of the rust and old sealant. The shop tells us that
if the tumbling process does not remove all of the old sealant, they will
not be able to apply their own sealant to the inside of the tank. My
questions for the group are: 1) Am I OK to continue with the main tank as
it is? The sealant has just minor bubbles in it in the areas where it is
present. In the areas where it is not present, the metal looks clean. 2) If
the shop tumbles the aux tank and is not able to remove all of the old
sealant - what are my options? Use the tank as-is with a lot of exposed
metal? Ask them to try to seal it anyways? Try to seal it myself?
 
I agree.  Did the inside tank coating;  it lasted 10 years before
leaking again.  Got lucky and found a local guy parting out a GMC and he
wanted $ 10 per tank.  I couldn't do that and gave him $25 per.  Not in
yet though and that is why our GMC can't move out of the pole barn!

> Best thing to do is take the tanks down to your local radiator/fuel tank shop and have them look at them....they will recommend the best solution. All
> the classic cars i have restored they have "hot tanked" them to clean them inside and out then sealed the outside with a corrosion barrier paint. As
> for the inside, unless they are heavily rusted they will leave them bare steel and as long as there is fuel in them they will stay in good shape.
>
> As far as coatings i have tried the usual's that are commercially available and find they tend to cause more problems then they are worth inside a
> fuel tank because unless the prep is done exctly as they say it doesnt stick [example: POR15 is a fantastic product and sticks like no tomorrow to
> rusted or sand blasted surfaces but will peel off in layers on smooth steel].
>
> YMMV but contaminated fuel systems are too much of a pain to deal with on the side of the road so let the experts deal with your tanks for the few
> dollars it really costs.

--
 
> I would still prefer chemical to mechanical removal.

On Ken's recommendation I googled chemical stripping (wondering what kind of results I would get :d ) and found a place not too far away. I called
them and they said that they don't typically do chem stripping for tanks, but instead they bake the tank at 800 degrees and that should turn the old
coating to ash, at which point that can wash and acid wash the inside. They then apply a water soluble rust inhibitor. $150. We just dropped it off. I
will report back on results
--
Corey
1974 Unidentified GMC Trim
 
Please let us know how it works out. I am very interested.

I have a pair of them here that have the opposite problem. Clean inside and badly rusted outside. I have not decided exactly what I will do.

In your case I like the idea of cooking them. One word of caution, if there are holes in the tanks that were soldered (like a radiator is soldered)
they will have to be re-soldered again. Solder melting points are in the 400F to 450F range. Pure lead is around 620F. Most radiator shops that
repair gas tanks solder them.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Ken im not sure if you could buy this over the counter but when the rad shop did our tanks they coated the outside in this silver looking paint
stuff....it was like rubberized paint..... the closest think i can think of as an example is Plasticote tool dipping rubberized products.

If i was playing around i might look at bed liner products to see if any of them would work as they are easy to apply and stick well.....a simple
walnut shell blasting of the outside of the tank to remove the rust without damaging the surface [sand blasting kills tanks and no one is gonna shot
blast them] and put on the bed liner product....probably out last the motorhome...might be worth a call to the manufacturer.

> Please let us know how it works out. I am very interested.
>
> I have a pair of them here that have the opposite problem. Clean inside and badly rusted outside. I have not decided exactly what I will do.
>
> In your case I like the idea of cooking them. One word of caution, if there are holes in the tanks that were soldered (like a radiator is
> soldered) they will have to be re-soldered again. Solder melting points are in the 400F to 450F range. Pure lead is around 620F. Most radiator
> shops that repair gas tanks solder them.

--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
I have Line-x on my 14 year old PU truck bed. That stuff is great. I also have used POR-15 for battery boxes and other stuff. The biggest problem
with POR-15 is it does not like sunlight which would not be a problem on a gas tank under the vehicle.

My biggest problem is the tanks are rusted on the bottom outside (inside is clean) and anything I use to clean it will open more holes. I have
available bead blasting and sand blasting cabinets at the airport but these tanks are too large to get into the blaster. I thought about soldering it
up, myself but I have never soldered any thing with that much of an area and so many holes in it. I have also looked as two alcohol tolerant epoxies.
They are very expensive.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
So I got the tank back from the 'Baker' and the filler Neck tube was handed to me separately. Im assuming this means it was soldered in originally?
--
Corey P /

Hilliard, OH /

1974 Glacier 26'

ION Wheels
 
They mistreated it. have them reimburse you for having a radiator shop
soder it back.
They do not come off by itself.

On Mon, Dec 30, 2019 at 9:24 PM Corey via Gmclist
wrote:

> So I got the tank back from the 'Baker' and the filler Neck tube was
> handed to me separately. Im assuming this means it was soldered in
> originally?
> --
> Corey P /
>
> Hilliard, OH /
>
> 1974 Glacier 26'
>
> ION Wheels
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmcrvparts.com
1-800-752-7502
 
yup i agree with Jim here...they messed up your tank and you need to get that neck soldered back on now....
--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
Well, I do not know if they are originally soldered in. If they are, then then the 800 degree baking process is definitely about the melting
temperature of every solder I have ever used. I guess it should be expected. I am surprised that they did not re-solder it back when they were done.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
I expect the shop that baked the tank is not in the business of tank repair. It will be a simple process for a decent repair shop to re-install the filler tube using solder. They will likely use solder to repair any other minor holes.

Les Burt
Montreal
'75 Eleganza 26'

>
> Well, I do not know if they are originally soldered in. If they are, then then the 800 degree baking process is definitely about the melting
> temperature of every solder I have ever used. I guess it should be expected. I am surprised that they did not re-solder it back when they were done.
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
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