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Fuel tank micro cracks


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 I've got 2 micro cracks on our 1984 Nissan Sunrader's  21 gal.  steel (iron?)  gas tank.   Leaks super slow.  No drips.  But always damp.   Been living with it but needs repair. 

 

1)  is that type of thing fixable? 


2)  does anyone have any experience fixing such things?  Might you share some learning?

 

3) If a new gas tank is the only solution where does one get one? 

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Fiberglass cloth with fiberglass or epoxy resin should work but the metal would have to be taken to bare metal with paint remover and sandpaper by hand. I would not recomend using any power tools that would make heat or a spark.

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Fiberglass epoxy...wish I'd known. I had a 84 Subaru with cracks in the tank. I'd get under there every other month or so cover it with some swipes of bar soap, zest if i remember. I did that for a coupe of years, crazy young fools what were they thinking? 

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So fiberglass cloth with fiberglass epoxy will bond and seal against the sanded metal (iron)  of the industrial-looking gas tank?   Just want to makes sure I'm on the same page (sometimes I'm reading a completely different book)

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And could you do it with the tank full?  So that area would be a humid with gas/fume, but not really wet.   Just asking cuz emptying gas tank is something I am not looking forward to doing.

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Back in the day,  the mechanic Frank would siphon gas out of the tank, clean the area up and with one of those old brass torch/s heat up a soldering iron and solder the tank!   I would wait outside around the corner. 

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I really loved the soap reply.  I was like yhgtbsm!  That led me down some interweb rat holes where I learned more about my dilemma.   Below are three links to lively conversations and a video (could that be you jjrbus?).  

 

Summary: 1) soap works in a pinch, is temporary, will work with gas spilling out. 2). Seal All and JB weld are better fixes but again don't expect it to be forever.  3) bubble gum mixed with gas makes napalm

 

https://www.s10forum.com/threads/has-anyone-ever-used-ivory-soap-to-stop-a-tank-leak.480326/

 

https://www.ttora.com/threads/ivory-soap-on-a-gas-tank.75551/

 

 

 

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21 hours ago, GothicSunrader said:

So fiberglass cloth with fiberglass epoxy will bond and seal against the sanded metal (iron)  of the industrial-looking gas tank?   Just want to makes sure I'm on the same page (sometimes I'm reading a completely different book)

Yes and tank would not need to be empty just gas level below where you're going to repair. If it's only a small area J-B weld would work too.

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JB Weld AND a coarse fiberglass cloth is about the best you can do for this kind of repair.

Clean, clean and clean the metal first

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1 hour ago, WME said:

JB Weld AND a coarse fiberglass cloth is about the best you can do for this kind of repair.

Clean, clean and clean the metal first

So,  the leaks are on the bottom of the tank.   Micro cracks.   No gaping wound.   Just immediately gets humid after wiping,  so you can see it's point of origin.   But not see the micro crack.   For a leak of this nature does the fiberglass cloth serve a purpose?   If so what purpose is it serving? 

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Fiberglass resin is made to be used with fiberglass cloth without using the cloth it's only good for some applications and would be same as painting with a thick sticky paint and probably would crack and peel off in the future. I have used it coating wood in boating applications without the cloth but I wouldn't recommend it on metal.

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11 hours ago, GothicSunrader said:

So,  the leaks are on the bottom of the tank.   Micro cracks.   No gaping wound.   Just immediately gets humid after wiping,  so you can see it's point of origin.   But not see the micro crack.   For a leak of this nature does the fiberglass cloth serve a purpose?   If so what purpose is it serving? 

 

Think of concrete with and without rebar. The JB Weld is very strong, but can fracture from movement, vibration. You would be surprised how much a fuel tank flexes. The old school solider and copper patch is stronger than the tank when done right.

 

There is also the coat the inside of the tank method...https://www.kbs-coatings.com/auto-fuel-tank-sealer-kit.html

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Well I found you a new tank. I have a Nissan with a 21 gallon tank and I didn't think replacements were available anywhere. On Ebay and pretty cheap. Seller has a very good rating. 

https://www.ebay.com/itm/GAS-FUEL-TANK-NS7-INS7-FITS-83-84-85-86-NISSAN-720-2-4L-L4-LONG-BOX-TRUCK-21GAL/123432587016?fits=Make%3ANissan&hash=item1cbd27cf08:g:3ugAAOSwuXlbxyWb

Manufacturer  has since gone out of business so these might not be around too much longer

Linda S

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Thank you Linda.   That is such a find!  I recently sealed it as suggested.   Seems good to far,  but expect it to be temporary.   If it starts leaking again soon I'll go the new tank route.    

 

Question about the new tank you found.   So I have 1984 Nissan Sunrader on a 720 2.4L pickup.  And new tank description says it fits,  but will it fit the Sunrader on that pickup?   How can I be sure?   My present tank seems more rectangular and "right angle-y".  The new one seems a tad different,  will that matter?  Will it be a simple plug 'n play? 

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Yeah you should show us. Sunrader did offer a 26 gallon tank for the Toyota but not the Nissan, Datsun since a 21 gallon tank was already available from Nissan for the king cab 4x4. I wouldn't worry about the fit. My Nissan has the tank for the 4x4 too and it fits fine. I could not find any for my D21 though. This one looks so much like mine I might buy one anyway just in case. It's cheap. Don't wait until they are gone forever or your going to regret it

Linda S

 

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Wow they did. Just looked at an 85 brochure and the extra capacity tank for the Nissan was a whopping 29 gallons. Crazy big tank for such a little truck. If that's what you have definitely get the inside coating job instead of trying to replace it. Pricey but your tank is gold.

Linda S

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My tank dimensions are

38" L x 13. 5" W x 14" H

 

Online volume calculator gives 31 gallons as capacity.  But tank is not a true rectangle so definitely less than that.   But I could see it being the 29 gallon one, maybe?   

IMAG0853.jpg

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2 hours ago, linda s said:

It sure sits close to the ground. I don't know if I would be comfortable with that. 

Linda S

Yea, it's definitely a low spot.  Clearance is not her strong suit.  Like 5 3/4".    Might ultimately be why I have micro cracks. One too many dings?  

IMG_0031.JPG

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Btw, one of the two trouble area looks like this fixed.  I did the repair with the tank full. I found if I rubbed ivory soap on the micro crack it would stop leaking even after vigorously sanding the area. So I was able to apply the "Seal All" to a dry surface.   I thought I try "Seal All"  first then if it leaks down the road try JB weld next. 

IMG_0032.JPG

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1 hour ago, GothicSunrader said:

Yea, it's definitely a low spot.  Clearance is not her strong suit.  Like 5 3/4".    Might ultimately be why I have micro cracks. One too many dings?  

IMG_0031.JPG

 

 

I would make some sort of tin shield, kinda thin, just to deflect road debris.

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  • 5 months later...

Linda S.  so I've still got the leak and the gas tank you recommended is out of stock.   Any idea where I can find a tank to replace my, what seems to be, 29 gal.  tank in 1984 Nissan Sunrader?  I'm over trying to patch it with products.  Doesn't last/work.  Thx! 

Edited by GothicSunrader
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No way your going to find a 29 gallon tank anywhere. They were all custom made for the Sunraders and supplier they used has been out of business for a long time. As I said before mine is a 21 gallon tank so still way larger than the Toyota's. These were used on the dual wheel cab and chassis and the 4x4 king cab truck. Nearest one I could find online is here but you would have to call and check. 200 miles but they do ship

Auto Recyclers - Auto Parts, Auto Repair (autorecyclerswy.com)

Calling local salvage yards would be a good idea too. Just be specific. Dual wheel truck or king cab 4x4 only. Dual wheels ones only go to 1988 but looks like the king cab 4x4 had the larger fuel tank well into the 90's. Colorado bet there are some of those 4x4's somewhere. Good luck

Linda S

Looked more. Try these places too

Auto Recycling Company | Commerce City, CO | Western Auto Recycling (westernautorecyclingdenver.com)

H&H Auto Parts | Cozad and Grand Island / Owl, NE & Denver / Boot Hill and Loveland, CO (handhautoparts.net)

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  • 6 months later...

Linda: S. hi again.  My 29 gallon gas tank problems have come to a head  snd I’m asking the shop to put in a new tank.  I have a 84 Nissan Sunrader.  Would you confirm that this link you mentioned will fit on my rig. The shop is staying they can find no options.  
 

https://www.nissanpartsdeal.com/parts/nissan-fuel-tank-assy~17202-11g00.html

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I don't know. Your truck has a wheelbase of 110 inches and mine with the larger tank has a wheelbase of 116 inches. Unfortunately my Sunrader is kind of covered with blackberries at the moment and I can't get under it to measure it for you. I did some measurements a long time ago and I know it will fit a Toyota with a wheelbase of 112 inches so only a couple of inches longer than yours. How long is that custom tank. I guessing it is at max length for the size of your rig for maximum fuel. That would give us an idea if it will fit and I will try to put some tarps down and measure my tank. 

Linda S

Yes I know I'm a bad Sunrader owner. Have a clunk in the drive line and guy who was going to work on it closed business apparently. Been sitting since

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Another thing. That part at Nissan parts deal might not really be available. They do that sometimes. I can't find anyone else who has this tank. Looks to be discontinued. BUT I did find one in Wyoming at this place. Closest one to Colorado and this place does ship.

Auto Recyclers - Auto Parts, Auto Repair (autorecyclerswy.com)

more info

Year
Part
Model
Description Damage
Code
Part
Grade
Stock# US
Price
Dealer Info Dist
mile
1987
Fuel Tank Assembly
Nissan Truck
236FA2D302194C79B9FA4B763E62FCF8001_thumb.jpgKing Cab, from 8/86, 21.1 gallon (6 cylinder, 4x4) 000 A
0
161914 $85
actual
Auto Recyclers USA-WY(Rock-Springs) Request_Quote 307-382-4222 Request_Insurance_Quote
Live Chat
254
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I ordered an aftermarket tank for my Toyota,  when I went to install it I decided it was poor quality and did not use it.    A local shop cleaned and lined my tank for $245, took 10 days to get it back.

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