Cracked my gastank

Well my 96 rmw was dumping gas from the top side. I was hoping it was a bad line or oring but. Turns out to be cracked. On the top side, above the strap on the driver's side. It didn't take long to realize there were no replacements available new so... I used the soldering iron and some washer fluid bottle scraps and melted it back together. I threw a fuel pump in too while I was at it. So far so good. Ive used the technique on lawnmower tanks for a while successfully in the past. I'll figure out how to post pics soon. Photobucket...hmm.

supposed to be pics there... that didnt work

I should add that I'm covered in poison ivy, which made this repair all that more fun.

You can get plastic welding tools, and polypropylene (I believe the tank is made of polypropylene) sticks to repair the tank. I do not know if the washer tank is the same material, and some plastics do not like to work together. Make sure you went about a half of an inch past the end of the crack so that it does not propagate.

Good luck with the poison ivy.

Well, I'm no plastic expert as you can tell, but I sure acts like hdpe, and has taken to the repair well so far. Time will tell. All the mower tanks I've done were hdpe #2. Roadmaster tank seemed no different other than size. I am curious what caused it though. Seems sort of common for 96 owners to crack tanks. Probably just stress from?

Cracks can develop in different parts of the tank. The cracked tanks are not limited to the 96, they occur in all years, and in the sedans as well. It is probably a cool spot in the plastic when molded.

I repair the lower part of the door panels (styrene) with MEK, and reinforce them with some "paste" made with scraps dissolved in MEK, and some nylon window screen for reinforcement. Just do not touch the visible side of the door panel with MEK on your hands, or you will leave an indelible print on the panel.

Fred Kiehl wrote:

Cracks can develop in different parts of the tank. The cracked tanks are not limited to the 96, they occur in all years, and in the sedans as well. It is probably a cool spot in the plastic when molded.

I repair the lower part of the door panels (styrene) with MEK, and reinforce them with some "paste" made with scraps dissolved in MEK, and some nylon window screen for reinforcement. Just do not touch the visible side of the door panel with MEK on your hands, or you will leave an indelible print on the panel.

I used to like building plastic models as a kid. I think most of that stuff was styrene. It was so annoying when I got a fingerprint somewhere. Never sanded off right.  I swear that testors brush on glue is just mek.  I need to do a little door panel repair in the future and will be using your method.

I should edit that I used a washer fluid refill bottle, not an actual gm washer fluid tank. I think it must read funny. I'm also not a linguist.

The Testor's plastic brush on plastic cement is probably either MEK or MEK substitute. You can get a quart of it from Home Depot or Lowes for about twice the price of a 1 oz. bottle of plastic cement.

Just make sure the panel is in position so that the crack is in its minimal visual position, and apply from the back. I often hold the panel in place with weights and packing tape. Let it set for a couple of hours before touching/moving it. I do the reinforcement after the basic repair has dried.

One way of stopping a crack from progressing, is to drill a hole at each end of the crack. This applies to either metal or plastic, and of course the hole must be filled.
One of the three left side tailpipes that I’ve had on my ’95 wagon was so close to the tank that it started to melt the corner slightly. These tailpipes, as many know, must be bent very accurately, or they will interfere with something along the route. Out of 3 tailpipes that I’ve had on the car, only 1 fit (the current one) correctly, and as I remember it is a Walker.

But back to the tank, which is of course marked “Do not Repair”!
SEM makes a two-part plastic epoxy that is formulated and sold for “problem plastics”, and lists a large number of different types of plastic that it works on. I’ve used it for years on many different plastic types, and haven’t found any to which it doesn’t bond extremely well. I used this to build up the damaged tank corner, a number of years ago, and it looks the same today as when I made the repair.

It has a couple of disadvantages: it’s expensive; about $50 for two large tubes, and it requires a special “gun” (another $50+) to use it correctly. I’m not certain, but I think that the product that they sell as “Plastic Bumper Repair” is the same thing, in smaller “finger squeeze” tubes for about $10-12. The other possible disadvantage is the very fast setting time, about 3 minutes—not much time to work.

I’ve noticed that “plastic epoxies” are starting to appear from other manufacturers, and are on the shelves in hardware stores. I haven’t used them, so I don’t know if they compare to the SEM.

Conventional epoxies, such as JBWeld may work on a few types of plastic, but there’s many that don’t. In the past, I’ve tried conventional epoxy on some plastics and found it can be easily peeled off after “setting”.

If this repair fails in the future, I'd probably attempt some epoxy, that sem stuff sounds promising but in the past I have not had great results with many "plastic" epoxies. It has been years since I tried any, surely things have improved. For now, Its still holding and my tank is still full. I don't use much gas.

Does anyone know, since our tanks are not available new, if the box wagon tanks are available new and might fit? Probably steel and set up with carb fuel system, but possible? I'd prefer a "new" tank if possible, since time is a wear factor on plastic.

The box wagon tanks are narrower than the bubble body tanks. They should bolt up to the body, but may have some issues with the filler. The pump may also work, because they used some TBI engines in the box wagons. The pump is the same size as the LT1 pumps. The fuel lines from the sender may also be shorter, but then again the newer senders may fit as well, or may be modifiable. As far as being available new, I do not know if they are.

I just looked them up on rock auto. they do make them, in the $90 realm or $135 with a whacky metal filler neck attached. there is a sending unit assembly with 2 or 3 lines available depending on engine but there is a significant "bubble" on the top side to fit the pump housing at an angle. That would likely be a problem. I don't recall how much room above the tank there was available.

There is about an inch of space above the tank. If a removable access panel is made, it could be shaped to give more clearance, but I do not know how much, or if the bump would encroach on other areas.

I looked for the tanks as well. The ones with the tube are for sedans. It should not be to difficult to weld a pipe on the side instead of the back, although it might tend to push fuel into the filler tube when going around right turns. It would also be best to have any changes made before any plating process. Maybe someone could contact the manufacturer too enquire about a tank for the 91-96 wagons. Some internal baffles could keep the fuel in the tank, and the opening could be designed to fit the later fuel senders.

I called a place that makes custom gas tanks. Boy are they expensive. The other side is that they make them from stainless steel. He guestimated it at about $850. If anybody is truly interested, the place is Rock Valley Antique Auto Parts, 815-645-2271. They are in Ill, and I guess shipping is extra.

Heat welding is really the only thing I would trust with polypropylene/polyethylene plastics. Those plastic epoxies just mechanically stick and have no true bonding capability with those series of plastics. Nothing really (chemically) affects them, which is why they're good for fuel tanks.

So, I'll post my stupidity...
Not often does the wagon see less than a half tank, but on my trip to st. louis to tow a car back, I was like "wow am I getting great gas mileage towing a trailer" Turns out 301 miles is what it takes to empty a tank completely, and 1 mile to coast to a stop. Lucky for me I was only about 2 miles from a gas station in the middle of nowhere Illinois. That could have been a MUCH longer walk.

I did not check that the gauge said "empty" after I did the pump. So, I'm empty at 1/4 tank. Gotta pull it again. 'DOH!

Check your gauge after a pump replacement before gas goes in. fair warning...

I've now got TWO tanks with a crack in that same location..... I'm going to glue a piece of pipe insulation foam over that spot on the next tank...... and maybe not tighten the straps so tight!....Somewhere in these forums, I posted some pictures of the access panel and module modifications I made that limit the access hole to the size of the top of the dome...... My access panel is the dome sheetmetal cut out of the floor of another wagon....... Quick questions for Fred..... Can a LT1 era fuel module be used in a TBI tank? Do they fit? Is the gauge sender compatible?.... LT1 pump is high pressure, but will it work for TBI (?) or should I stick with TBI spec pump?
The latest tank I got out of a 91 Caprice wagon has a bit different looking baffling and the module won't go the last half inch before bottoming (tank depth shrunk?)..... I'm thinking that the fuel sock will have a tough time with that, so I've temporarily got a spacer in there to try to push the bottom and top farther apart before I install the tank, but I'm also thinking that spring-loaded LT1 module might be a good upgrade...

Both modules will work. The LT1 tank module pushes the pump against the bottom of the tank with a spring. I do not know what the minimum install height is, but the return line that is used to hold the pump mount only allows the pump mount to move about an inch before the line hits the bottom of the tank. There is a spacer built in, so it will give the sock clearance, the TBI pump sender does not have much of an extended piece to protect the sock. Stick with the correct pump for the engine. Using an LT1 pump may cause excess return line pressure, and cause the fuel pressure to be too high for the TBI. When installing the pump in an LT1 module use the looped hose, or it will negate the spring "suspension" of the pump.

The 91 tank may me different from the others. There are some odd little differences in the 91, and I doubt that I have found them all. Measure the other tanks to check for differences.

Gluing a piece to the tank will not hold. The glue will not adhere to the plastic of the tank.

There should be a rubber strip on the floor doubler channels above the tank. If they are missing, the tank may hit something it is not supposed to in the area of your cracks.

For whatever it's worth, my repair is still holding strong!