Repairing or Replacing a Fuel Tank


This page includes information from discussions on the CJ-3B Bulletin Board regarding:

Epoxy Repair

Dave Hatch's tankEd Wilson: "My gas tank started leaking last spring -- RUST! After finding that replacements aren't always available, I patched mine. After removing the tank, I flushed it with water to clean it out and find the holes. Making sure all the leaks were located, I began the cleaning process.

"Remove any old paint, undercoat, etc. Using Scotch-Brite and 220 grit sandpaper, I took the tank to the metal around the holes. Then use a good commercial grade degreaser on the area. The product I used is Sprayway C-60 Solvent Cleaner & De-Greaser. At this point, you should have a bright, shiny area around your leaks that is totally clean. Now for the J-B Weld. This is an epoxy product available in most auto parts and hardware stores. Mix and use according to the directions.

"This should get you going until you can find a replacement. Mine was in service for about a year with no leaks."

Bart McNeil describes his step-by-step experience: "Eastwood has the materials for the plastic lining of the gas tank I believe. It is a recommended fix for restoring old leaky tanks if you want to retain the original tank. If you only have one leak in your tank you are probably in pretty good shape. I'm in process of restoring mine so I'll mention the technique I used.

"My tank had been dry for months but I poured water in my tank and made sure the entire inside was rinsed with water and drained. Mine is a replacement tank probably from the 1980s. It was made by Tankauto and was purchased for $89.98 (the price tag was still on it). Visually it is just about identical to an original tank and it fits the 3B nicely. I knew I had a leak but I couldn't find it. The bottom center rear corner was heavily rusted and pitted.

"I removed the rust and old paint with a 3M stripping wheel and it was effective but didn't get down to the bottom of the rust pits. A wire wheel cleaned out the remaining rust and I found a pin hole at the bottom of a pit. I then poked at other pits with an old wood drill and was able to push through the thin metal at 16 other pits. I enlarged the holes with a 1/16-inch drill to make sure I was working with relatively good metal. The 17 holes were within about a 3 square inch area. I used a sanding disk of about 80 grit and roughed up the metal to be repaired (at least an inch beyond the holes on all sides). The heavy grit is to assure the repair patch grips the metal tank.

"I have found that the most convenient material to use on a patch is the epoxy which comes in two connected tubes. A couple of ounces costs about $2.50 if I recall. With this product you cannot mix the epoxy and the hardener wrong. I also used two layers of fiberglass cloth. I spread epoxy on the repair area and then placed a saturated fiberglass cloth over the whole sanded area. I used a flexible piece of plastic as a squeegee to press the saturated cloth against the metal. Then I applied the second layer of saturated cloth and gently squeegeed it down as well. It hardened in about 2 hours (gentle heat will speed up hardening).

"Since it was on the bottom of the tank I could have left it as is, but I chose to sand it with progressively fine disks to blend the edges of the patch into the existing sheet metal. With careful sanding and painting the patch should be invisible. When complete it is a good idea to rinse the tank again with water to remove any metal fragments or grit. Once rinsed and drained an old trick is to pour in a pint or so of alcohol and slosh it around the entire inside of the tank. It will absorb any remaining water and will leave the inside of the tank water-free when the alcohol is drained. Total cost of materials was maybe $4.50."


Welding a Gas Tank!


Oldtime: "In the interest of safety I feel the topic of repairing an original fuel tank by means of welding, needs to be revisited. I am here concerned with the common advice on fuel tank repair: filling a gasoline tank with water to purge it of volatile fumes before the welding procedure. I've heard and tested this theory myself many years past. Furthermore I have made my living as a certifiable welder and a metal fabricator."

The Problem

"In this ill-advised procedure, one is to fill the tank completely full of water to displace all potential fumes. This in reality is a practical impossibility. The smallest of possible gas pockets can explode upon ignition. Steel must melt to be welded, and this occurs at around 2800 degrees F. The water would have to boil away from the tank side to allow the steel to reach this required temp. Even soldering/brazing procedures require high temps. So in this instance the steel, expanded by heat distortion, leaves contact with the cooling H2O and thus recreates that dangerous volatile gas pocket. Theoretically the only exception here is the very remote possability that one needs to weld the edge of the flange joint to seal a leak at this point. Here the metal is in fact removed far enough away from the cooling purge water to allow a sufficient metal temperature to be reached without metal deformation. But this flange joint in reality doesn't leak at its very edge, rather it is a crimped seal away from the flange edge. I have exploded a tank attempting to weld a flanged joint. Apparently the water could not displace all the volatile fumes trapped within the joint."

The Solution

"Now on to the proper and only technique anyone should pursue. Before one weld repairs the tank, it must be purged of volatile fumes. The most practical technique for achieving this is by drying out the tank. First drain every single drop of gasoline one can get out by draining. Secondly one needs to displace fumes by drying with an inert heated gas. The 134 Willys exhaust is perfect for this, because of the tailpipe diameter. Simply put the tank filler neck up and over the tailpipe, runnig the tailpipe deep into the fuel tank. Idle the Jeep for one full hour. Your tank is now purged and nearly ready for safe welding repair. Before attempting to weld the tank however one should use subsequent caution. Place the tank behind a safe barrier. Extending only a torch flame around the personal barrier, attempt to ignite any fumes at the filler neck by inserting the flame; this is the scary part for the uninitiated. The tank is now completely purged, ready to be safely repaired."

Daryl: "Oldtime, you have let the cat out of the bag on how simple it is to weld on gas tanks. I have been doing this for years, and people think I'm crazy. Filling with water is not only ineffective, it it also promotes rust in the tank once the repair is finished."

Plastic or Steel Replacement?

Tim asked on the CJ-3B Bulletin Board, "If you were to replace the gas tank, which would you use and why?"

Steel fan: "If I were making the choice, I would choose metal. Reasons are, metal tanks lasted 50 years, if they weren't parked and abandoned outdoors with only a couple of pints of gas in them. Most of the time when they rust out it is on the bottom where the dirt and debris aren't cleaned out once a decade or so.

"Problem I suspect with poly tanks is the integrity of the UV inhibitor in the plastic. How long will it last? is the question. There just isn't a track record for a 20-year history. Perhaps someone is aware of a cheap plastic compound that will hold up under UV rays for 10+ years, but I can't think of one. And you can believe that the manufacturers are using the absolutely cheapest material they can find that provides a reasonable facsimile to something that will last beyond a few years. Material cost of a poly tank is probably about $5 ea. The tooling, marketing and merchandising costs about $20 ea. Poly and steel tanks being about the same retail price, I would take a steel tank with no doubts."

Uncle Flatty noted, "I have had new poly and new metal. The poly wears out at the gas cap very quckly and leaks profusely."

Jyotin voted: "Metal. I have used both kinds. There is no comparison here.

"I no longer own the Jeep with the poly tank, however it was constantly out of gasoline and the shop smelled of gasoline fumes all the time. That is how I knew it was out of fuel -- the smell went away."

Poly fan: "I got a poly tank direct from MTS Company about 10 years ago, after fighting, cleaning and sealing the old tank with no success. I bought a replacement steel tank from JC Whitney (which didn't fit) then a second steel tank from Specialty Jeep Parts, which rusted above the fuel level the first year, and I spent a weekend cleaning the rust out of the lines, fuel pump and carb. The poly tank fits fine, has a top suction unlike the steel, and it seems to me like the cap fits pretty tight."

Dick Willliams: "I have the MTS tanks in both of my CJs. one is in the '54 CJ-3B and the other is in my '68 CJ-5. They both fit and I have not had problems with the cap. I put an MTS check valve cap on the '54 which helps it from leaking on side hill conditions. There are no baffles. And you do need to ground the sending unit."

Bryan: "I put in a plastic tank I bought direct from MTS. Love it. You need to replumb the fuel line because the suction is from the top, and you need to ground the fuel level sensor, but it was worth it."

Plastic early-style tankEd Wilson: "Parts dealers have a poly replacement tank (left) for the B model and having just pulled out my patched and leaking metal tank once again, I'm trying this tank. It's black and is made to use the original sending unit and cap, however it has the fuel outlet on top. The price is $9 more than the steel item.

"The poly tank is great. It's made in the USA and the look and fit are well within my requirements. You have to look very close to see the difference. It was actually easier to install than the original, with no fittings on the bottom to allow for, it just slid right in. The retaining strap, sending unit, and cap all fit perfectly and it includes a new gasket for the sending unit. The only reservation was the line fitting; it is a barbed (for hose) brass elbow threaded directly into the poly itself. I would have preferred provision for all steel line, but allowing for a rubber hose section in the line probably reduces the effects of normal vibration on the threads in the poly material.

"My original installation was to simply run a length of rubber fuel line from the end of the steel line to the barbed fitting, clamp, and go. But go I did not. Apparently, at speed, the rubber section would collapse, causing fuel starvation and shut down. I then went to a steel line that I ran from the original steel, cutting and flaring to butt to the barbed fitting. This allowed me to use approximately 1" of hose as opposed to the 16 or so inches originally. This seems to have solved the fuel flow problem. Unless you have the convenient rust hole I have, you will have to bore a hole to route the fuel line down behind the tank. Going straight back and down will let you line up with your original line (80K JPEG)."

Three "B" Tanks

All CJ-3Bs used a gas tank with the filler neck pointing sideways and angled up. Later editions of the factory Service Manual show a diagram of the tank with the filler neck angled back as well as up; this tank was in fact used in the CJ-5 and CJ-6 but not the 3B.

SenderOldtime: "Model CJ-3B fuel tank identification:

1) W-O Part no. 640685 fuel tank assembly (weldment) is used up to serial no. 54-17328 (early 1954). This first tank is a direct carryover from the CJ-2A and CJ-3A, and only accepts the Part no. 640694 gauge (tank unit) for 6-volt systems (right). Aftermarket 12-volt gauge tank units may be available. This gauge mounts with 5 No. 8-32x1/2" screws. This tank is held down with two clamps and one strap. The forward hold down clamp/strap combination is positioned outboard to inboard over the tank assembly. These early CJ tanks differed from later assemblies by the clamp bracket that is positioned and fastened upon the rear upper edge of the tank. A short clamp is attached here and fastened to the bed of the Jeep. These tanks were used only on CJ-2A, CJ-3A and CJ-3B models having the old style individual instruments.

2) W-O Part no. 810427 fuel tank assembly uses the same gauge (tank unit) and is identical to the previous in every detail except that this tank assembly deletes the rear clamp bracket that was soldered to the top rear. See tank shown in picture at top of page. With this tank a new hold down strap, Part no. 810400, is positioned fore/aft over the assembly. These tanks were used only on CJ-3B models having the old style individual instruments.

3) W-O Part no. 911895 fuel tank assembly was used after serial no. 57348-34452 (begining 1957). Three different gauge (tank units) are used depending on the voltage and make, both King Seeley and Stewart Warner. This style of gauge (40K JPEG) mounts with 6 No. 10-32x1/2" screws. The location of the gauge is identical to that of previous tanks. This tank uses the same fore/aft hold down strap as the previous tank. These tanks were used only on CJ-3B models having the new style cluster instruments."

Note from Derek: MTS Company lists serial number 57348-39838 as the starting point for the later style tank, rather than 57348-34452 which was the introduction of the new instrumentation. Dealers using the Omix-Ada repro parts catalog list the changeover date as 1956, so owners of 1956-57 Jeeps should check carefully to confirm which type of tank they need.

Tank Hold Down Strap

Two types of metal hold down straps were used: a left-right strap on the first style of tank, and a front-back strap on the other two.

William: "I feel kind of dumb having to ask this. How exactly is the retainer strap placed on the fuel tank? I bought a new tank and strap from Krage for my '54 3B in Florida. The strap is an Omix-Ada part (#A1472K). Any pictures?"

Wade '55 3B Lawrence: "I have a 1955 original one-owner. I will try to describe the gas strap arrangement. The tank is secured by one strap. The strap is approximately 3/32-inch thick and 1 inch wide. The strap runs from front to back across the tank. The strap crosses the tank about 10 inches from the outside of the tub. (The tank is 24 inches across) The strap in front of the tank has a small "L" shaped piece of strapping spot welded to the strap. It has a 3/8-inch hole through the strap and is bolted to the floor of the tub as close to the tank as possible.The other end of the strap has an offset bend and a 3/8-inch hole and is bolted to the floor of the tub just to the rear of the drivers seat."

Ed Wilson: "There should be a hole in the floorboard at the front and one at the rear of the tank for the bolts, roughly center of the tank. The strap should fit over the tank from hole to hole. I believe there was also some welting or rubber between the strap and tank. It should look something like this from the side:


R. Jack: "Bravo and well done for the key board drawing. How did you do the rear reverse slant?"

Ed Wilson: "The back slash is just above the enter key on my keyboard. Feels good to help as I have used this BB and website for so much. What a grand bunch of Jeep guys."

William: "So, I should have to bend the strap over the tank? The one I bought is two pieces shaped like this. The v-shaped ends are bent like hooks. the other have holes drilled in them."


Early '54 3B

Andy: "On my '54 3B, the tank strap goes side to side, attaching to two brackets, one on the left and the other on the floor on the right, with a bolt holding the two pieces together. From your drawing and description, it looks like this is the setup you have."


H. Wooldridge: "There should be a hook attached to the body on the passenger side of the tank, or a bolt hole. The long strap attaches there and the short one to the body on the driver's side of the tank. You use a long bolt and cinch the two pieces tight with a thin rubber or cloth insulator between the strap and the tank. It just has to be tight enough not to slide around -- no need to collapse the sides. Also make sure there are a couple of rubber strips under the tank to raise it off the floor pan a 1/4-inch or so to allow moisture and dirt out the bottom. The strap should miss the sending unit by a small amount but maybe the edge will touch a bit."

Ed Wilson: "Interesting. Now I'm wondering why there were two tank strap arrangements. My front-to-rear strap looks original, complete with the captured nuts at the bolt locations, so I had never questioned it. Anyway, looks like Andy's arrangement is what the Krage strap was made for."

Bruce W.: "My pretty-much-unmolested '53 has the strap cross-wise, even tho the tab that it hooks to on the left side is broken off from the tub (I found it down in there next to the tank tho). It also has a "hook" that bolts to the floor at the rear of the tank and hooks over a tab on the back of the tank."

Ernie: "I always thought that the early 3B's were side-to-side and the later ones were front-to-rear. My brother's '54 3B is serial number 454GB2 15727. It is very original and has the fuel tank strap from side to side just like my '52 3A."

William: "I also posted this on the Early CJ-5 board. I found out that 5's with underseat tanks have the front-to-rear strap.

"My '53 3B has the side-to-side strap arrangement complete with the hooks on the body. My '54 has the caged nuts in the floor and no evidence of the hooks on the body. One is right in front. The other is on the riser behind the tank. Maybe this was a design change by Willys to cut down on the number of different parts on the same assembly line. The 3B's (IIRC) and 5's were built on the same line. Maybe the M38A1s too.

"Theory: The A1 came out in '52. Leftover side-to-side straps were to be phased out of the flatfender. Their stock lasted into the middle of the '54 production year on the 3B. By time the 5's hit the showroom floor, only one style of tank strap had to be handled on the assembly line. Willys made a design change to save money and time on the line. They also used up all of the old parts. Waste not, want not!"

Thanks to Ed Wilson, Bart McNeil, Oldtime and the other contributors.

See also the kind of restoration process offered by Moyer's Fuel Tank Renu in Pennsylvania, which is what I did with my tank. -- Derek Redmond

See Fuel and Temperature Gauge Fixes on CJ3B.info.

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Last updated 15 February 2007 by Derek Redmond redmond@cj3b.info
All content not credited and previously copyright, is copyright Derek Redmond