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Jim Stabe
Jim Stabe
San Diego, Ca
(829 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

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Hirsch gas tank sealer rant
Posted by: Jim Stabe
Date: August 11, 2015 10:58PM

I fabricated the fuel tank for my car from aluminum. When I made it several years ago I pressure tested it and it held 5 psi overnight.

Tank6 (Medium).JPG

When I finally put gas in it several years later I found a couple pin hole leaks and I also had concern that the alcohol in the gas might attack the aluminum. The Hirsch sealer had some good reviews so I bought the kit to both seal the leaks and coat the inside with an alcohol proof barrier coating. [www.hirschauto.com] . I followed the instructions to the letter etching the interior with the material supplied in the kit. I took extra care to make sure the inside was completely dry (per instructions) and actually ran the heated air through the tank twice as long as specified. Next came the actual sealing solution which got thoroughly sloshed around and the excess drained. I allowed the material to cure several times longer than the instructions called for and when I filled the tank the leaks were no more.

Fast forward a year to this week. My fuel gauge was acting funny like the float on the sender was sticking so I pulled it out to check. What I found when I looked inside the tank was all the coating was peeling off the walls in large sheets. I was afraid that the peeling material could clog the fuel pump ( I have an in-tank pump for F.I.) so I removed the tank and pulled out the pump and filler neck as well. Good thing I did because the sock over the inlet was covered with pieces of the shed coating. Spent the whole day scouring the inside of the tank where I could reach (I put 4 baffles in it). I called Hirsch this morning and they told me that their instructions say that it does not adhere well to new metal (isn't that what the etch is supposed to do?). I reread all their literature and there is absolutely no mention of adhesion problems on new metal (I wouldn't have bought it if that were the case). I emailed them pointing out their oversight and am still waiting for a reply.

From all the online reviews of users sealing rusty tanks I have to believe it is a good product for that application but I strongly advise against using it on a fabricated tank. The picture shows what I have removed from the tank so far.

Hirsch tank sealer.JPG



Edited 1 time(s). Last edit at 08/11/2015 11:00PM by Jim Stabe.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: Hirsch gas tank sealer rant
Posted by: BlownMGB-V8
Date: August 12, 2015 12:47AM

I'll never use tank sealer again. I tried it out a couple decades ago on 3 tanks and all had peeling issues. My conclusion was that it is a temporary band-aid, and not a very good one at that. Maybe OK for getting a few more weeks out of a rusty tank but it's far far better to make sure of your welds and not count on a sealant. Where fuel tanks are concerned I even look at gaskets with a jaundiced eye. I certainly feel your pain, it's no fun dealing with the aftermath.

Jim


88v8
Ivor Duarte
Gloucestershire UK
(1041 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
1974 Land Rover Lightweight V8

Re: Hirsch gas tank sealer rant
Posted by: 88v8
Date: August 12, 2015 05:01AM

And after all your work. Well, I believe you have a few lawyers over there.
I bought an (expensive) alloy tank for my TR6. The maker indignantly denied that it would be affected by ethanol.
Yeah
Never got around to fitting it so I don't know, but I think you were right to be concerned. There's no shortage of scholarly papers on the subject of protecting against alloy corrosion, the difficulty lies in getting from lab to real world.
Meanwhile the politico ignoramuses who mandate this green crap drive around in their limos and don't give a hoot. I bet none of your GOP candidates mentioned getting rid of ethanol.

Ivor


Orange Alpine
Bill Blue

(45 posts)

Registered:
12/20/2010 07:36AM

Main British Car:
1967 Sunbeam Alpine 2.5 Ford Duratec

Re: Hirsch gas tank sealer rant
Posted by: Orange Alpine
Date: August 12, 2015 07:53AM

Very disturbing, especially the part about a dry tank developing leaks. How in the world can that happen?

The Hirsch literature cannot be believed. They say the silver sealers (POR 15?) will last no more than 6-12 months. They are confusing their product with POR. My POR lined tanks have been "wet" for 8 years and are doing fine.

Ethanol should not be mentioned. Hirsch says their product will resist the stuff. End of THAT discussion.

Bill


roverman
Art Gertz
Winchester, CA.
(3188 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Hirsch gas tank sealer rant
Posted by: roverman
Date: August 12, 2015 12:55PM

Jim S., I would peep "performance E85" website. They have been users of E85, for years. If you used 6061 aluminum, it's better for corrosion resistance. A.I.R., I used "Protec"gas tank sealer, only steel tanks, but worked very well. Forced dried with hair drier, definitely "Hi Voc". How about anodizing ? Good Luck, Art.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: Hirsch gas tank sealer rant
Posted by: BlownMGB-V8
Date: August 12, 2015 04:52PM

Anodizing will be tricky with the baffles. Hard anodizing would be the safest. If it's made of 6061 that will help a little on the corrosion problem with ethanol.

Jim


DiDueColpi
Fred Key
West coast - Canada
(1365 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
I really thought that I'd be an action figure by now!

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Re: Hirsch gas tank sealer rant
Posted by: DiDueColpi
Date: August 13, 2015 01:03PM

I think that now that the tank is contaminated. Your only real option is to reweld the affected areas.
And really, that was the only option from the start.
I'm right there with Jim. Sealants are just a disappointment looking for an opportunity.
To get all the old stuff out I generally use a bag of self tapping screws. Just dump 100 or so in the tank add a little water and shake the living daylights out of it. All of those little sharp points do an amazing job of cleaning it up.
Cheers
Fred



Jim Stabe
Jim Stabe
San Diego, Ca
(829 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

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Re: Hirsch gas tank sealer rant
Posted by: Jim Stabe
Date: August 13, 2015 04:14PM

There are areas where the coating is adhering and it is pretty durable. I'm happy with all the areas I can get to but there are 2 compartments that I can't see. I put everything back together this morning and will run it this way for a while. I'll take the fuel pump out periodically and see if there is any debris on the sock filter. If the shedding continues to be a problem, I may make a new tank out of stainless, there are a number of things I would change in the design due to changes I have made to the car since I built the tank. Gotta love those guys at Hirsch


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: Hirsch gas tank sealer rant
Posted by: BlownMGB-V8
Date: August 14, 2015 11:25AM

Yeah, the sad thing is that in a practical sense it's probably just as easy to make a new tank as to fix that one.

Stainless is a great idea, but thin stainless is a real challenge to weld. Gas shielding the back side becomes a real necessity. I just welded up a couple of small stainless cans and it was really tricky to get usable settings on the TIG machine and even then I was running too hot but if I turned it down any more the pulse function wasn't working. I wish you the best of luck with that, maybe your machine can handle lower settings better than mine. Stainless is also noticeably heavier than mild steel. Wonder how well titanium holds up to methanol? It is becoming almost affordable and is pretty easy to weld as long as you get a long enough gas shield. I watched a video of a company that makes pretty complex titanium tanks. They used an internal purge and a trailing gas shield about 3-4" long. Lots of warpage though.

Jim


Jim Stabe
Jim Stabe
San Diego, Ca
(829 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

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Re: Hirsch gas tank sealer rant
Posted by: Jim Stabe
Date: August 14, 2015 09:35PM

Actually, I looked up weights and stainless is less than 1% heavier than mild steel - I was surprised too. I was actually thinking about making a mild steel tank. I could bend the body out of one piece with just an edge weld at the top peak. I would weld nuts to the inside that would allow the baffles to be bolted in and the body, baffles and end caps could be zinc plated for corrosion resistance. I could bolt in the baffles and solder on the end caps. The mounting flange could be welded onto the body before plating as well as the nut rings for the filler, pump and gauge sender. I would also gain an extra couple gallons of capacity since the recesses for the original mufflers would not be needed. If I made it from 20 gauge with bead rolled stiffeners it would weigh slightly less than the current aluminum tank which is .090" 5051. I might incorporate a couple straps underneath to support the thinner material.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: Hirsch gas tank sealer rant
Posted by: BlownMGB-V8
Date: August 15, 2015 01:10AM

Never would have thought that.

Well, with a good coat of paint on the outside the main cause of steel tank failure was always internal corrosion, but with ethanol added to the gas it's like a constant supply of Drygas so that's become pretty much of a non issue.

I do like stainless though and it can be thinner than the mild steel it takes the place of, in fact for beading it just about has to be. Which means a stainless tank might be lighter than the steel one and perhaps the aluminum one as well. I didn't mean to put you off on the welding, I'm not saying it's a huge problem, just needs practice. Maybe a good bit of practice but the main thing is getting the welder set up properly. I have a pulse module in my old TIG machine and that really helps a lot, I'd hate to have to weld stainless without it. SS, oddly enough does not like a lot of heat. So what I did on this thin stuff was set the background current as low as I could get it, set the pulse frequency to maybe half a second between pulses, then gave it enough heat on the pulse (with the pedal) to form a small puddle while the pulse was on, then move and repeat. That keeps the metal cool enough that it doesn't burn. Once you get the hang of it, it's a lot like doing spots on sheet metal with the MIG. A lot of very bright light helps. You can simulate the pulse module just with the pedal, some professional welders are really good at that. But it does take some pretty good coordination. If I didn't have a pulse module I'd try it.

I'll try to measure the thickness of that metal I've been working with tomorrow. The job was a success. I did have to close up a few holes but it kept getting easier as I went along with fewer holes. By the end I was doing a pretty decent job of it. I'll try to post a photo too so you can see what it was.

For the back shield I bought the matching fittings to put a T and a small ball valve on the front of the welder where the gas line for the torch hooks in, then ran a 1/4" plastic line over by the bench which I can turn on and off with the ball valve. Most of what I've done the last few days was handled easily enough by sticking the hose through the hole in a holesaw cutout. It worked very well. Plenty of room for imagination there.

Another consideration if you weld SS is the chromium and nickel. You shouldn't breathe the vapors. On a big job it can make you sick, and a gas tank might be big enough to do that. I rigged a fan to blow fresh air into my helmet for a big job after I started showing symptoms the second day. You can buy those now but I just rigged something to bring in fresh air. It was cooler that way too.

The soldering was something I always had issues with unless it was galvanized to begin with. Plus once you solder you can't weld. Well, it's weld, then braze, then solder with no going the other way. (then sealants) I like to keep my options open by staying at the beginning of that list if at all possible, in case a subsequent repair is needed (or I find a leak or want to go back and change something).

Jim


Jim Stabe
Jim Stabe
San Diego, Ca
(829 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

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Re: Hirsch gas tank sealer rant
Posted by: Jim Stabe
Date: August 15, 2015 02:24AM

I've tried welding some thin stainless with pretty dismal results. If I can do a mild steel tank with just one edge weld along the long dimension I can just do a fusion weld with no rod and almost no chance of a leak. I would do the same with the end caps but if I have the parts zinc plated, the weld would destroy the plating. Are you saying the alcohol in the gasoline would prevent internal rusting and not require plating?

edit - I just did some reading and it seems that zinc (galvanizing) might not be the best corrosion protection against ethanol since the acetic acid produced by the water absorbed by the ethanol is highly corrosive to zinc. A better solution might be electroless nickel that is being used in Brazil that is very resistant to acetic acid. More research required.



Edited 1 time(s). Last edit at 08/15/2015 02:39AM by Jim Stabe.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: Hirsch gas tank sealer rant
Posted by: BlownMGB-V8
Date: August 15, 2015 10:48AM

Don't know for sure but if you think back to the days before they started adding ethanol, rotted out gas tanks were a lot more common than they are today. Any water would lay in the bottom of the tank and just about any tank ended up with some water in it from condensate if nothing else. We'd add Drygas when it started interfering with how the engine ran. Drygas was nothing but pure ethanol which absorbs water. So today with ethanol included in the gas, even at 10% that's a lot healthier dose than we could ever manage with the drygas. So at least in theory the tank stays dry, no water floating around, and internal rust isn't a problem anymore. When was the last time you saw a rotted out tank? I'd bet it was on an old car that was made before they started adding ethanol to the gas.

So you'd expect that a steel tank with a good paint job would be just fine. And that's what Moss and VB sell.

Jim


Jim Stabe
Jim Stabe
San Diego, Ca
(829 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

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Re: Hirsch gas tank sealer rant
Posted by: Jim Stabe
Date: August 15, 2015 10:57AM

Are they made with coated steel or just bare mild steel that's painted on the outside?


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: Hirsch gas tank sealer rant
Posted by: BlownMGB-V8
Date: August 15, 2015 04:13PM

Don't know for sure, I thought it was bare mild steel.

The thin stainless I was working with turned out to be .025" thick. It is definitely doable. Here is my practice piece, it was pretty gnarly:

IMG_0061.JPG

Here are the parts I made with that material:

IMG_0058.JPG

The cross tube bosses were the last welds, and the best, needing very little dressing up for a nice appearance. The butt seam welds were the first and also the ugliest but even they were acceptable. A little thicker metal would be noticeably easier.

Jim



Jim Stabe
Jim Stabe
San Diego, Ca
(829 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

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Re: Hirsch gas tank sealer rant
Posted by: Jim Stabe
Date: August 15, 2015 04:42PM

That top one looks like my try with stainless.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: Hirsch gas tank sealer rant
Posted by: BlownMGB-V8
Date: August 16, 2015 11:44AM

Yeah, it started out pretty nasty. No gas shield on the bottom which makes it worse too. (you get a burnt sugar appearance) The gas shield on the back side seems to help with not burning through also. You can use copper for a backing plate which helps a lot but oxygen will still get in.

The breakthrough point was the stuff at the top and the bottom dot. That was where I got the power under control. With this stuff it's best to creep up on the power level, and like I said earlier, the pulse technique really pays off. I forget which element it is that burns off and makes the nasty black oxide, maybe the chromium, but whatever it is you can basically boil it out of suspension by getting the metal too hot. So using a pulse, you establish your background for a stable arc and shield gas flow at a level which allows the metal to solidify. Then you use your pulse, whether auto or manual, to create a small puddle where you can bind the parts and add filler as needed, just a quick dab and shoot for decent flow at the edges before dropping back to the background arc and letting the puddle set up or solidify. Keep it short. Too much heat and you burn it and get a black oxide on the bead. I mentioned a half second cycle, some use less but that's the complete cycle so the actual pulse is much shorter, and you have to allow enough off time to let the heat flow away from the puddle. That's really the key.

If you don't have auto-pulse, I would try setting up a couple of stops on the pedal. One to set the minimum for the background arc and one to set the max for the pulse. If you have a switch on your torch handle that'd then be real handy for starting and stopping.

Also, naturally the part will heat up as you go so that less heat is needed and there is more risk of burning through. That's when you back off on your pulse a bit, same for thinner sections and bigger gaps just like any other welding.

For the pulse itself I lean more towards using a higher power and a shorter duration. The longer the puddle is molten the more it will tend to boil and you don't want that. Also the higher the power level the better job I get of wetting the metal being joined, and the better flow I get across gaps and holes. But with higher power a short pulse becomes pretty critical. Go a little too long and you burn through. So you are balancing the power against the pulse length. Pretty tricky if you are doing both freehand at the same time and requires a ton of practice. Once you get in the zone with it you can make beautiful beads that way, but still, I'd try to standardize one or the other. The time base determines the bead pattern. A shorter cycle means a finer pattern but gives less time to reposition between puddles and stable hands when the pulse hits is what you need for a pretty bead. On a lot of stuff that's just not easy enough to do to make it worth the effort but it's mostly a matter of how much time you spend on making it perfect. The good news is, that it is a very consistent metal to work with and will behave the same every time. So we have that going for us. And one advantage of doing manual pulse is that off pulse is free time. There is no reason you can't use that as you like and stretch it out for repositioning, getting a fresh grip on the filler rod or whatever since you're not dealing with molten metal until you hit the power.

Jim


Jim Stabe
Jim Stabe
San Diego, Ca
(829 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

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Re: Hirsch gas tank sealer rant
Posted by: Jim Stabe
Date: August 16, 2015 12:30PM

Have you tried silicon bronze rod on the stainless? I used it on some stubborn leaks on mild steel coolant pipes and it worked really well. It is sort of halfway between a braze and fusion weld and it would preclude doing a fusion weld afterward but I really like the stuff.

For now, I'm going to use the aluminum tank and check the fuel pump sock periodically for any coating. If that becomes a problem I will probably make a mild steel tank since I found several people who built them and have had no issues with rust after several years of use. I can always open the drain plug and drain out any accumulated water. Best result will be if the aluminum tank doesn't shed any more - wish me luck.


ghornbostel
Greg Hornbostel
Nebraska
(76 posts)

Registered:
09/02/2013 01:41PM

Main British Car:
1957 TR3 Buick 231 evenfire V6

Re: Hirsch gas tank sealer rant
Posted by: ghornbostel
Date: August 16, 2015 12:55PM

I'm with Jim Stabe on the si bronze tig braze and stainless. I used the POR liner on my steel tank and no problems so far but it has only been less that a year. After a summer with the stock tank I'm thinking a I need a larger tank in the 18 to 20 gal range and it will probably be made out of stainless.
Greg


Jim Stabe
Jim Stabe
San Diego, Ca
(829 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

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Re: Hirsch gas tank sealer rant
Posted by: Jim Stabe
Date: August 16, 2015 02:51PM

Post up your tank build Greg, I'm interested in how it works out.
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