Gas tank crack near top/attempting repair

My 96 RMW has a crack at the top of the tank. I've done research and found these tanks are hard to come by and not made anymore and are not repairable. I am attempting a repair with a plastic welder by melting in HPDE material... Drilled holes at both ends of the crack. Didn't work, still leaking. Next I did a thick layer of black permatex RTV... Waiting for that to cure and will check tomorrow. Has anyone found unversal tank that I can make work on a 96 wagon?

These cars all have plastic tanks that I am sure are all starting to crack due to age. There must be a replacement option or another 5 years or so and these cars are dead...

Keep your eyes open, there are some tanks around. Although it would be expensive, maybe you could get a custom aluminum one made. You would need a baffled center sump to fit the center of the tank. The tanks for the earlier wagons might be adaptable to the 91-96. Steel tanks are made for the previous generation of wagons, and they used similar pickups for the TBI cars.

Thanks. I just saw a 94 parts wagon nearby I may be picking up, I can get the rest of the pieces I am missing for my car off of it. Just worried all of the tanks on these cars are now time bombs due to age.

Fred Kiehl wrote:

Keep your eyes open, there are some tanks around. Although it would be expensive, maybe you could get a custom aluminum one made. You would need a baffled center sump to fit the center of the tank. The tanks for the earlier wagons might be adaptable to the 91-96. Steel tanks are made for the previous generation of wagons, and they used similar pickups for the TBI cars.

I havent checked, but assuming dimensions of a tank would fit under the car reasonably, with the two hose inlets on the passenger side for filler neck and assuming the sending unit would drop into the center hole, would a tank like this function? I cant post links yet, but Look up Dorman part 576-335. This tank looks close.

Also what do you mean by baffled center sump to fit the center of the tank?

Purplezombie wrote:

Fred Kiehl wrote:

Keep your eyes open, there are some tanks around. Although it would be expensive, maybe you could get a custom aluminum one made. You would need a baffled center sump to fit the center of the tank. The tanks for the earlier wagons might be adaptable to the 91-96. Steel tanks are made for the previous generation of wagons, and they used similar pickups for the TBI cars.

I havent checked, but assuming dimensions of a tank would fit under the car reasonably, with the two hose inlets on the passenger side for filler neck and assuming the sending unit would drop into the center hole, would a tank like this function? I cant post links yet, but Look up Dorman part 576-335. This tank looks close.

Also what do you mean by baffled center sump to fit the center of the tank?

The plastic tank has a baffled sump in the center to keep the fuel from going to the side, front, or back under assorted maneuvers. Without it, you would have no fuel for the pump to pick up when turning, stopping, or accelerating. When you drop the tank, look inside, and you will see the part. I do not know exactly how it is designed, but it keeps fuel on the pick-up when the tank is getting empty. The other option is to use Holley HydraMat on  the bottom of the tank.

The tank that most closely fits the 91-96 tank is Dorman 576-377. https://www.dormanproducts.com/p-24262-576-377.aspx?year=1989&make=Chevrolet&model=Caprice&parttype=Fuel%2520Tank&origin=YMM

It may require some modifications, and/or a different sending unit. It is for 1977-1990 wagons. It is a 22 gallon tank, but putting channels in it for the underbody rails may take a gallon out of it. I do not know if it has a center sump/baffle. The tank could be modified before installation to eliminate explosion hazards. It may also require an external fuel pump.

The plastic tank has a baffled sump in the center to keep the fuel from going to the side, front, or back under assorted maneuvers. Without it, you would have no fuel for the pump to pick up when turning, stopping, or accelerating. When you drop the tank, look inside, and you will see the part. I do not know exactly how it is designed, but it keeps fuel on the pick-up when the tank is getting empty. The other option is to use Holley HydraMat on  the bottom of the tank.

It may require some modifications, and/or a different sending unit. It is for 1977-1990 wagons. It is a 22 gallon tank, but putting channels in it for the underbody rails may take a gallon out of it. I do not know if it has a center sump/baffle. The tank could be modified before installation to eliminate explosion hazards. It may also require an external fuel pump.[/quote]

Awesome! I'm going to check if my black RTV patch worked. It's probably a short term fix, but if it buys me time to buy a tank like that dorman 576-377, I do have access to a tig and mig welder at work and can do mods... I'll let you know if it works for the people like me who creeped through years of forum posts trying to get this info.

I had the same issue with the tank in the wife's wagon. I also unsuccessfully tried plastic welding the crack...

We found someone local that was parting out a wagon that thankfully had a usable tank.

Has anyone talked to a pro plastic welding/tank fabrication place to see what they say. Perhaps it is because of contamination, but often that can be gotten around by using an external "plate" type patch that weld on the outside away from the contaminated crack and interior of the tank.

Do we know for certain what exactly the material is?

The tank is high density polyethylene.

I didn't know there are two kinds of HDPE, as I have only dealt with one kind in the industrial stuff I worked with.

Cross linked or not cross linked is the difference in name but big difference in properties. Cross linked is a cured thermoset plastic that changes chemistry in curing so can't be remelted in welding.

Non cross linked is a normal thermoplastic and can be welded.

Test is to see if it melts or not.

Here is an article the describes them both and how to fix them.

HDPE repair

After my attempts with the plastic welder, yes it melts. But I wasnt successful with it. I did a huge thick layer of black rtv so hopefully that will hold up.

Since it melts, it should be a reasonably simple fix, with a reliable result. I looked at the instructions, and it is pretty straight forward. They used some stainless steel screen to reinforce the weld. They suggested low density PE for the repair material.

Fred Kiehl wrote:

Since it melts, it should be a reasonably simple fix, with a reliable result. I looked at the instructions, and it is pretty straight forward. They used some stainless steel screen to reinforce the weld. They suggested low density PE for the repair material.

I tried it twice and didnt have much luck. I used the stainless mesh to give it strength and prepped the surface by sanding it and wiping with alcohol. I did use the cheaper $16 harbor freight tool, maybe with a better higher watt plastic welder I would have had better luck. My black RTV patch so far has held, but since its not good for gasoline there is no tellling how long it will last. I'll be on the look out for another tank or maybe I will try to make that dorman tank work. Took dimensions of my tank to compare and they werent far off.

If the cracked area is a flat surface, could you make a gasketed bulkhead plate? Fasteners might be a challenge, but something like a push-through anchor might work. I'd put out a call for a donor tank first. Try the Facebook group to reach a larger (but more dithering) audience.

If patching is absolutely the final answer you resort to, try these guys. They make the only adhesive that bonds to this material. For the flame treatment they recommend, use a paint remover type electric heat gun.

https://mrstickys.com

Check the flame treatment video.

https://www.youtube.com/watch?v=DuipkpUt2Tk

""Check the flame treatment video.

https://www.youtube.com/watch?v=DuipkpUt2Tk""


""For the flame treatment they recommend, use a paint remover type electric heat gun.""


Open flame on a fuel tank might lead to a bad day for everyone.

If I recall, they did not recommend the paint remover electric heat gun. They said that a heat gun did not work. I suggested that the concerned people look at the flame treatment video because of that.

dmg4 wrote:

If the cracked area is a flat surface, could you make a gasketed bulkhead plate?  Fasteners might be a challenge, but something like a push-through anchor might work.  I'd put out a call for a donor tank first.  Try the Facebook group to reach a larger (but more dithering) audience.

No, the crack is along the top of the curve of the tank unfortunately.



This is the RTV patch, so far so good, but if I start to see a leak I will be ordering that Dorman tank and adapting it.

If this RTV patch fails (I think it will) this looks like a good solution if the stuff will hold up to gas. I went with RTV because of the flex. Here in Florida when it gets to 100+ degrees I would think the tank would expand and break off anything that isn't flexible.

Thanks for the help guys. If I go the modified dorman tank route I'll post pics.

I got the Dorman tank Fred recommended. Dimensions were very close. Inside of this tank does appear to have baffles. One question though, how important is it to have the smaller upper rubber hose? It's not there on this tank like the original.

It accesses the tank at the top, so you do not get a bubble trapped in the tank when filling it. You could make a vent with some small exhaust pipe, and weld it to the tank. The diameter is about 3/4 of an inch. You will also have to shorten the filler neck, and flare the end to mate with the 91-96 filler hose.

I do not think the metal one has a check valve, or anti-theft ball valve. You may want to reshape the sender mount, or make one that matches the 91-96 units. 93-96 senders are a lot better design.

Fred Kiehl wrote:

It accesses the tank at the top, so you do not get a bubble trapped in the tank when filling it. You could make a vent with some small exhaust pipe, and weld it to the tank. The diameter is about 3/4 of an inch. You will also have to shorten the filler neck, and flare the end to mate with the 91-96 filler hose.

I do not think the metal one has a check valve, or anti-theft ball valve. You may want to reshape the sender mount, or make one that matches the 91-96 units. 93-96 senders are a lot better design.

The sender mount on this tank does have a pretty big hump to it and mounts at an angle. My 96 tank sits flush, if I have to I will cut off the hump and go with a flat plate type mount. I'm not sure if the normal fuel sender unit is the same diameter as this one either, I wont know until I drop the tank again.

The O-ring for the OEM tank is 4 3/8 inches OD. Beyond that the flange is bolted and does not use a lock ring.

If you cut an oval out so that the high end is longer than the low end, and turn it 180 deg., you could make it almost level. It would move the opening to the back a little, but it would be almost level. The distance it moves may put the vertical sender in the middle of the baffled section. Holley makes a universal sender that might fit in the vertical rendition of the sender opening.

Thanks for the idea, I'll look into it. Unfortunately, my car started making a squeeking noise from the engine that has worsened over the past few days and I use it as a daily. I'm 90% sure its a pulley, but everything looked worn out up front so I ordered some parts.

I ordered ACDelco 38145 Tensioner with pulley, ACDelco 38001 Idler Pulley, ACDelco 6K642 Accesory Belt and Gates K040365 Drive belt. All should get here this weekend.

idler pulley bearings often make squeeky noises when they start to go.

A member has a complete tank available in the for sale section.

94Woody wrote:

A member has a complete tank available in the for sale section.

I saw that. Unfortunately it's in NC, a little too far out of driving range for me and shipping cost for a gas tank would be high. A 94' parts car just popped up near me that I may pick up and if that works out I'll take it's tank, complete my car, return this steel tank, and part the rest out. Thanks

"" Unfortunately, my car started making a squeeking noise from the engine""

Spray Armor All on the drive belt. If the squeak instantly quiets, it is coming from the belt itself. Our cars seem to get a problem as they age and the various pully surfaces get polished. A new belt will help, but only for a short time. The only permanent "cure" is a segmented groove serpentine drive belt, which is getting hard to find.

You might also want to look at the harmonic balancer ring to see if it has become unbonded.

Purplezombie wrote:

94Woody wrote:

A member has a complete tank available in the for sale section.

I saw that. Unfortunately it's in NC, a little too far out of driving range for me and shipping cost for a gas tank would be high. A 94' parts car just popped up near me that I may pick up and if that works out I'll take it's tank, complete my car, return this steel tank, and part the rest out. Thanks

If you go and pull the tank and buy it would you be able to sell the plastic baffle/cup that is at the top of the filler? I found mine has a broken off ear when I pulled the tank to do the fuel pump and they seem to be pretty rare in unbroken condition.

Thanks for any help you could give.

Purplezombie wrote:

94Woody wrote:

A member has a complete tank available in the for sale section.

I saw that. Unfortunately it's in NC, a little too far out of driving range for me and shipping cost for a gas tank would be high. A 94' parts car just popped up near me that I may pick up and if that works out I'll take it's tank, complete my car, return this steel tank, and part the rest out. Thanks

If you go and pull the tank and buy it would you be able to sell the plastic baffle/cup that is at the top of the filler? I found mine has a broken off ear when I pulled the tank to do the fuel pump and they seem to be pretty rare in unbroken condition.

Thanks for any help you could give.

[quote="booster"]

Purplezombie wrote:

94Woody wrote:

A member has a complete tank available in the for sale section.

I saw that. Unfortunately it's in NC, a little too far out of driving range for me and shipping cost for a gas tank would be high. A 94' parts car just popped up near me that I may pick up and if that works out I'll take it's tank, complete my car, return this steel tank, and part the rest out. Thanks

If you go and pull the tank and buy it would you be able to sell the plastic baffle/cup that is at the top of the filler? I found mine has a broken off ear when I pulled the tank to do the fuel pump and they seem to be pretty rare in unbroken condition.

Thanks for any help you could give.[/quote

Sure, I'll look at the car tomorrow and let you know. Can you post a pic of exactly what you are talking about? Also, are you in FL?

Purplezombie wrote:

booster wrote:

Purplezombie wrote:

94Woody wrote:

A member has a complete tank available in the for sale section.

I saw that. Unfortunately it's in NC, a little too far out of driving range for me and shipping cost for a gas tank would be high. A 94' parts car just popped up near me that I may pick up and if that works out I'll take it's tank, complete my car, return this steel tank, and part the rest out. Thanks

If you go and pull the tank and buy it would you be able to sell the plastic baffle/cup that is at the top of the filler? I found mine has a broken off ear when I pulled the tank to do the fuel pump and they seem to be pretty rare in unbroken condition.

Thanks for any help you could give.[/quote

Sure, I'll look at the car tomorrow and let you know. Can you post a pic of exactly what you are talking about? Also, are you in FL?

Thanks, I would appreciate it.  I am in Minnesota so it would have to ship if that is possible.  With the tank out it probably would be easy to get off the filler.  I would gladly pay for shipping and your time if you are willing.

The four screws around the perimeter hold the bucket I need and the three in the middle should hold the bucket to the fill tube ass'y. If you pull the tank with filler it should come out complete.  If you cut the filler hoses to get the tank, taking out the three in the middle probably will let the filly push out through what is probably a rubber gasket under the plate.  Then the four screws on the perimeter would release the bucket.  Others should be able to let  us know if that is correct.

If you buy the parts car would you be able and willing to cut a part of the floor from the tailgunner seat over the gas tank when you remove it? See my WTB ad: https://gmlongroof.4umer.com/t15673-wtb-piece-of-metal-cut-from-wagon-jump-seat-floor

Thanks.

I'll let you both know if I end up purchasing it.