Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 More worries - cracked gas tank.

Mr.Morgan, very sorry to hear about your problem. Regrettably, it is a common fault

Thank you for the support and detailed description and many thanks for making the pictures available as well, I had some issues with the uploading tool...

It was more difficult to get a picture of the trail, but its certainty leaking from the mounting bracket as the trails stops (https://drive.google.com/file/d/1OglfaAAIiEQ8Dcq3Td6-zelJ8YQJIcwS/view?usp=drivesdk)

The straps actually feel pretty tight so the cracking of the brackets seems to happen regardless. Not the most impressive design from the factory

The car is located in Norway, but we have a local Morgan dealership here as well, so will discuss the problem with them as well

I agree with you from seeing that photo, it does look like the crack has propagated through the tab weld and into the tank skin and is not from above. I think it will be a tank out and repair or replace, not a simple job. The thin standard tabs will still crack even with tight straps but maybe not so easily? The bonded on strengthening brackets do seem to work, mine have been on for over 10,000 miles with no signs of cracks now. I would do the bonded extra tabs even if the tank is repaired, don't forget the lower tabs as well when doing the mods. I will send the MTWC tank repair article to you.

I had a discussion with a TM member yesterday who pointed out that I haven't posted photos of my repair brackets to reinforce the mountings under the fuel tanks.

Here are the blanks I cut out (along with the cardboard template):


Folded brackets. Note the tabs to wrap around the base to overlap the sides and also the scuffing up of the metal surface to provide a good key for the adhesive:




And the finished job with the brackets held in place with PU sealant.

Looking good Bunny could you mark up the dimensions of the brackets on the template and what thickness alloy did you use?

The alloy was 2mm thick. Sorry, I did this job over 5 years ago and the template is long gone. I seem to remember that it didn't take too long to make with an old serial packet...

CAD (cardboard aided design) is highly underrated.

I have to admit that I checked my fuel tanks many, many times, and kept the belts quite tight. Gave me a new thought: I am a bit intrigued by the Plus Four, but my faith in the bonded aluminum chassis is challenged by the poor design/implementation of the aluminum fuel tanks in our M3Ws.

These are two very different construction techniques.

The M3W fuel tanks are welded aluminum which is a somewhat specialised process

The bonded chassis is effectively gluing aluminum panels together, often using high temperatures and pressures in the curing process. This is an extremely well tried and tested process widely used in the Aircraft and Automotive industries. A major benefit of a bonded aluminum construction is it's resistance to cracking

as in no stress riser points within chassis itself.