Author Topic: What now? Gas tank problems.  (Read 912 times)

Offline Chanman09

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What now? Gas tank problems.
« on: February 05, 2023, 10:19:15 AM »
  Too long/ didnít read: Dropped the driver side tank on my 1986 c20. Was cleaning it up and found a small rusted out section. About the size of a pencil eraser. Do I get a complete new tank or try to patch it?


This weekendís project started out well. After a week of rain and letting things dry out a bit, I crawled under the 1986 c20 on Friday evening and power washed sand and dirt and dirt dober nests off the under side. I was pleasantly pleased with how little rust there was. I mean, there was plenty,  but not what I was expecting.

Saturday morning, I took the kids to my mothers house and I did some chores for her. My dad passed away in April, so sheís always happy for me to do a little here and there. I came home to an empty house, as my wife had a day planned with her bestie.

Now to the truck tank.

I sprayed the bolts on the gas tank mounts with some penetrant and got my tools and things ready. I crawled under the truck and removed the exhaust shield that was in the way of my ratchet.

The first bolt for the tank strap was the toughest sucker Iíve encountered in a while. I was wishing for an air ratchet or an impact wrench. I was looking for a cheater pipe that would fit but the space wasnít allowing it. So I decided to move to some other bolts. If they were all going to be like this, I was going to need a new plan. These other bolts were pleasant. So I loosened them just enough, as to not get the remainders in a bind. I used some more juices on the stubborn bolt and went to have a beer and rest my arms and neck. It finally became easiER and I managed to turn it with a lot of cussing and heavy grunting. Neighbors probably were wondering what was going on. Lol.

I wiggled the tank out of its position and used my giant pry screwdriver to help get the stud of the strap out of the frame hole it was hung on. As it dropped, I was able to disconnect the hoses from the hard lines running to the passenger side. The rats were kind enough to chew through the electrical lines, so that wasnít an issue. Yet.

I used my leaf blower to blow the dirt off and sprayed down the sending unit area with some lube juice.

Then I masked up and put on some goggles and crawled under the truck with an old electric drill equipped with a wire brush wheel.  I had a neck gaiter leftover from my COVID times and looked like a mercenaries from a video game. I wriggled and slid all under the cab and bed. Brushing off much more dirt than rust, but both. I had to come up for air a couple times and realized my hair was now a matted mess full of dirt, rust and sweat. Yuck! 

After I was pleased with my job I started slapping on the rust converter. I went with a watery,pre diluted version that Iím sure I overpaid for, but seemed idiot proof. I slathered it all over any spot my brush would fit. I felt like Van Gogh or maybe pollack as I completed my masterpiece. I only dropped a little of the nasty stuff on my forearm and got to feel it sting a little. The smell was a cross between the sickly sweet smell of fresh roadkill and an old banana. Magnifique.

I come from out of the shadows into the daylight to get after the gas tank.


I work the hoses off the filler neck and replace the neck back in its spot, holding it on with the gas cap tightened down. Iím sure Iíll forget that detail and be looking for that part later on. I get a hammer and screwdriver and take off the sending unit ring. It disintegrates. Great. Luckily it was nearly opened and I used 2 screwdrivers to turn the ring the rest of the way. I pull the sending unit out.  Yeah.  That thing was shot. Good! Just as I suspected. This isnít going to be a waste. I place the rotten unit in the back of the truck to hang out and I drag the tank to a comfy chair so I can sit and scrape.


I get a wire brush and get to scraping. I opt for the manual way so I donít hurt something on accident. Top of the tank cleaned up nice. The side opposite the strap bolt holes did too. At this point I was debating to take the straps off or just roll with it. I decided to roll as therust that was present didnít see too bad.

Iím getting pretty much done and I come to the last section of what would be the forward most, bottom left corner of the tank.  Whatís this?  Could it be?  No. It is!!  A hole!!   Son @7 @ 81@#!!

Well now hereís the dilemma. My hundredish  dollar project of a new sending unit and fuel pump and lines, could now become a 2 or 3 hundred dollar project depending on how detailed Iím getting.

Should I solder the hole and pray? JB weld like YouTube seems to be a fan of? Or just bite the bullet and go with new stuff?

Iíve looked at   and it looks like they have everything in stock. $100 tank. And straps and sending unit and lines if I need them. And selector valve and etc etc etc. all I see is dollar signs and Iím not trying to make a show car here. Lol. But I do want to drive the thing.

Iím just looking for advice and maybe some comfort. Lol. If yíall know of a place that has half price parts, that would be helpful too.

Thanks! Have a good one!



Edit: grammar.
« Last Edit: February 05, 2023, 10:27:55 AM by Chanman09 »

Offline Mike81K10

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Re: What now? Gas tank problems.
« Reply #1 on: February 05, 2023, 12:01:28 PM »
I would highly suggest a new tank(s). I had rust and corrosion problems with my fuel system as well and installed a whole new fuel system except for the selector valve which I repaired. You can see my build thread for my 81K10 on how bad my sending units were corroded and other parts. My bolts and nuts on my rock shield for my tanks were not in the best shape and took a lot of lubricant and time to soak, about a week and was spray about 4-5 times. It cleaned up and nuts came off eventually. Don't force them because they have small diameter threads and can break easily. Just takes time and you can use a wire brush or your wire wheel on that drill to clean up the threads once you get it down. Keep in mind, when safe to use a torch works wonders on getting off rusted nuts and bolts.
"Tell me and I forget. Teach me and I remember. Involve me and I learn." -Benjamin Franklin

Offline Chanman09

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Re: What now? Gas tank problems.
« Reply #2 on: February 05, 2023, 07:37:08 PM »
I knew that was the right answer. I just didnít want to face it. Lol.

I was waiting to see if there were a dozen responses of times others had welded some beer cans over the hole and been fine for a few years. Lol. I knew it was a long shot.

Iíll check out your build now. Iím still pretty new here and havenít dug real deep in any one section.

Thanks for the advice on the heat. I remember watching my dad do it, but really didnít think about it for rust in my case.


Offline JohnnyPopper

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Re: What now? Gas tank problems.
« Reply #3 on: February 06, 2023, 01:06:10 PM »
Okay I'll bite

Had a 64 Porsche 356 in another life, notorious for rusting between the bottom of the tank and some padding it rested on.

New one was cost prohibitive at that time in my life.

I remove it, and found that there were tiny pinholes from rust. Had it cleaned at a radiator shop.

I brazed the pinholes, and then layered OS JB weld over the repairs.

Lasted for the 20 years I owned it.

FWIW  ;)
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Chanman09

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Re: What now? Gas tank problems.
« Reply #4 on: February 07, 2023, 07:18:16 AM »
Perfect!!

Just the story I was looking for! Lol

Iíll Just buy a new tank. If it was $1k Iíd be welding It up. But I guess since itís just a hundred or so Iíll take the proper route.

The Porsche sounds like a cool ride!

Offline zieg85

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Re: What now? Gas tank problems.
« Reply #5 on: February 07, 2023, 09:47:27 AM »
I put a poly tank in mine.  It was about the same cost as a steel one
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline JohnnyPopper

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Re: What now? Gas tank problems.
« Reply #6 on: February 08, 2023, 07:27:14 PM »
Perfect!!

Just the story I was looking for! Lol

Iíll Just buy a new tank. If it was $1k Iíd be welding It up. But I guess since itís just a hundred or so Iíll take the proper route.

The Porsche sounds like a cool ride!

Sound like a plan...:)

Porsche was a great ride... I miss her at times, especially when I see another one.
What is different, is like so many rides through the years, is I don't have any regrets. I just smile thinking about the memories.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction