Background #
Well, I hadn’t planned to replace the petrol (gas) tank on my 72B but I found it became necessary to undertake a New Petrol/Gas Tank Install. Unfortunately this realization came to me slowly, at first, and then rather urgently. The slow warnings were that once I was able to drive the car and fill it up, I was quickly getting sediment and blockage of the fuel filter. As the car had sat for a while I got some advice and tried adding a fuel filter before the fuel pump by cutting the hard line from the tank and using about 3 feet of fuel line to make a loop that allowed me to reach the filter from through the battery box. The plan was to see if the sediment would get itself out over time and I could clean things up using quite a few, but cheap, fuel filters.
This solution was in place for about an hour when I went to fill the tank up and see if this would disturb more of the sediment and get the clean up process going. While filling the tank up, I planned to get it really full and that’s just what I did. Full to the extent that I actually got a little backup and overflow out of the fill neck. Good, I thought, that’ll get anything off the top of the tank. Then I noticed that there was fuel on the ground below the exhaust pipe! A closer inspection revealed that fuel was apparently leaking out of the top of the tank and pouring down onto the exhaust’s rear muffler.
At this stage I started to wonder how hot the exhaust would have to be to ignite the petrol that was dripping on it and recalling the fact that my fire extinguisher was back in the 77B at home. This also reminded me that I really had been meaning to buy another one for the 72. It also crossed my mind that I was glad I had significantly increased the “agreed value” of the 72 with Hagerty Insurance now that I was driving the car.
I was not far from home, 3 to 4 miles max, and as the car hadn’t so far started to combust I decided, perhaps foolishly, to drive it home. This worked fine and while I was watching constantly in the rear view mirror, to see if flames were pouring out the back of the car, they didn’t and I made it home safely.
So, now I’m pretty certain that the gas tank needs to be removed for further analysis. Great, but how do you remove it? Well, as I discovered, it’s not necessarily that difficult – maybe I was lucky.
Draining the Fuel Tank #
My first step was to drain the freshly filled tank. Although my tank had a drain plug, I went to the other end of the fuel system for greater control of the evacuation of the fuel. I pulled the fuel line from the carbs and then redirected this into my gas container and turned the ignition on to use the fuel pump to do the work. This allowed me to control the output of 2-2 ½ gallons of fuel into my container and I could then cut off the supply and dump the fuel into my Dodge Durango. I repeated this process until I could tell by the sound and signs of air bubbles when the tank was almost empty. At that point I used the drain plug in the tank to get the final drops out. Great – empty gas tank, what’s next?
Removing The Tank #
I removed the hard line connection from the tank with a 5/8” open wrench (spanner) and after this I removed the air vent connection that is right next to the fill pipe and released the lower hose clamp that holds the rubber connector from the fill pipe to the top of the tank neck. I loosened this enough that the tank neck should come away from the rubber connector hose with gravity, in due course.
From checking underneath the car I discovered that my tank was held in place by some nut and bolt combinations and others had a captive nut mechanism with a bolt head inside the trunk. I removed the bolts from the captive nuts that were the 2 rear positions (along the back edge of the car) and the one on the passenger side and two on the driver’s side. Yours may be different as I don’t know if this was normal/factory for this combination.
To give me more room to work I jacked up the rear end of the car and put a plastic stool underneath the tank to help break its fall should gravity take control of the procedure. I then removed the nylock nuts that remained holding the tank in place. These came off relatively easily and with a rubber mallet on top of the stool I had the tank under control from free-fall when the last nut was removed. I was able to then lower the tank with final separation being the tank filler neck from the filler rubber hose.
After the tank was out I then removed the sending unit by tapping to reverse the locking ring mechanism and then removed carefully the sending unit and rubber sealing ring and placed them in a safe place for later. For more about this and the removal/install of the sending unit see another article in this section.
Problem Identification/Sourcing a Replacement Tank #
My initial inspection didn’t show any major or obvious holes but there was some bubbling of the paint on the tank particularly at the rear of the tank or the edge that’s towards the front of the car. I decided to have our resident MG Doc, John Mangles, take a look at the tank. His trained eye noted that the tank must have rusted out and have been filled with bondo at some stage. Not really a surprise but the verdict: New Petrol/Gas Tank Install!
So, where to get a tank? Moss Motors ones seemed quite expensive, even after going through various sources with discounts and John mentioned that they had been “not available” for a while. I had read online (MG Experience) about some aftermarket tanks made in Canada. Seems that B-Hive (no longer trading as of 2022) sells these and also they are on eBay fairly regularly. I hit a little bit of luck when the B-Hive had these on special for $179 (reg $199) just when I needed it and so I went with the B-Hive (prices were back in 2008).
The tank arrived safely and is apparently “hot dipped” for protection. The only differences from the original I could see was that there is no drain plug and there’s no interior section or baffle to protect the sending unit from fuel ‘sloshing’ around affecting the fuel gauge reading. Not a big deal and who has a gauge that accurate anyway!
It was pretty clean and shiny but I cleaned it quickly and then proceeded to prepare it for paint to protect it. Some thoughts about using POR15 for protection, particularly on the top that is apparently prone to rust. On reflection this might be overkill and in the end, and for speed, I just used some Restoleum Auto primer and then a matt black top coat in rattle cans.
I gave the tank 2 coats of primer (about and can and a half) and then 2 coats of black which seemed to only use 1 full can. I had masked and taped the tank filler neck edge, the vent and hard line connector threads and the sending unit hole from the inner edge where the rubber seal seats. The rattle cans seemed to do a good job and I only managed to get a few small runs when I tried to get too much primer or paint on in one coat.
Once the paint had dried the final preparation was to stick on the rubber packing strips to the ribs on the top of the tank. I was going to re-use these from the old tank but in the end I used some new materials from the B-Hive along with a new tank neck grommet – might as well do it right, right! I stuck the strips in place using some 3M 77 aerosol glue that I had also used for installing my interior carpet. This seemed to work fine. I also reinstalled the captive nut holders that seem to just clip on to the tank over the holes. Remember to put these over the right holes and, unlike me, make sure the tabs holding the nuts in place at really tightly clamping the nuts in place. I’ll explain more.
So, now we’re ready to reinstall the tank. Have to fight gravity again and I am wondering whether I can do this or whether I will need to draft in some additional help. Well, actually, I found that using the stool for an assistant allowed me to lift and hold the tank long enough to get one corner nut in place with the other hand. I was then able to get a second corner nut in place and from there things went fairly smoothly. After I had the nuts installed I worked with the bolts lining up with the captive nuts.
You may need to use a screwdriver or something to help align the captive nuts correctly and then tighten the bolts. I had one issue with one of these where the bolt wasn’t straight and then seemed to bind up. I then couldn’t get the bolt out and discovered a spinning captive nut! Arggh, and of course it was one on the back edge where there’s little to no room to work between the tank and the rear valance. This was my only problem and I have left it for a rainy day since my initial attempts didn’t work. Hence the need to check these more closely when you put these back on. You have been warned!
After reinstalling the hard line, sending unit and filler neck I put in some petrol and tried things out. The pump “ticked” just long enough to make me nervous and then it stopped. It seemed all was well and then I tried to fire the engine and sure, enough, it works. I ran the engine enough to ensure the pump was getting fuel and so it looks like all is well. I haven’t yet been for a tank fill up, bit hopefully now I’ll ensure any petrol that ends up on the ground only comes from a backup in the filler hose and nowhere else! Still, I do now have that fire extinguisher for the 72 as well! Safety Fast!
With luck you found this article useful.
Other Materials #
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